Additional information on publications by Martin Nyffeler

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2022  Oophagy in spiders: consumption of invertebrate and vertebrate eggs — Nyffeler M & Gibbons JW — Journal of Arachnology 50: 33–38   doi> 10.1636/JoA-S-21-016 
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In this paper, we present an update on our knowledge on egg predation (oophagy) by spiders. Based on a survey of 233 reports, ghost spiders (Anyphaenidae), lynx spiders (Oxyopidae), jumping spiders (Salticidae), and yellow sac spiders (Cheiracanthiidae) were the most prominent groups of spiders engaged in oophagy. Around 75% of the reports referred to the consumption of lepidopteran and spider eggs worldwide. Another 10% referred to the consumption of eggs/embryos of anurans – especially predation upon embryos of glass frogs (Centrolenidae) by spiders from the families Anyphaenidae and Trechaleidae in the Neotropics. The remaining 17% included rare instances of feeding on eggs of coleopterans, dermapterans, dipterans, heteropterans, homopterans, hymenopterans, acarids, neuropterans, opilionids, and squamates. Our study demonstrates that oophagy in spiders is much more widespread than previously thought, both geographically and taxonomically. The finding that spiders feed on eggs/embryos from so many different invertebrate and vertebrate taxa is novel.

Keywords: Anyphaenidae - Cheiracanthiidae - Oxyopidae - Salticidae - egg predation - Invertebrata - Anura - Squamata

2022  Spiders feeding on vertebrates is more common and widespread than previously thought, geographically and taxonomically — Nyffeler M & Gibbons JW — Journal of Arachnology 50: 121–134   doi> 10.1636/JoA-S-21-054 
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According to a recent global literature survey, a total of 39 out of the 129 known spider families (~30%) contain species capable of capturing vertebrate prey. The finding that the percentage of spider families engaged in vertebrate predation is so high is novel. Two groups of vertebrate-eating spiders are distinguished: ‘‘habitual vertebrate- eaters’’ vs. ‘‘occasional vertebrate-eaters’’. The habitual vertebrate-eaters comprise ten spider families (Araneidae, Atracidae, Ctenidae, Lycosidae, Nephilidae, Pisauridae, Theraphosidae, Theridiidae, Trechaleidae, and Sparassidae) to which can be attributed 91% of all reported vertebrate predation incidents. The habitual vertebrate-eaters have evolved prey-capture adaptations such as (1) sufficient physical strength coupled with large body size, (2) the use of potent venoms, and (3) the use of highly efficient prey-catching webs. By contrast, unexpected feeding on vertebrates by the occasional vertebrate-eaters (i.e., Actinopodidae, Agelenidae, Amaurobiidae, Anyphaenidae, Barychelidae, Clubionidae, Corinnidae, Ctenizidae, Cyrtaucheniidae, Deinopidae, Desidae, Dipluridae, Eresidae, Filistatidae, Gnaphosidae, Haplonoproctidae, Linyphiidae, Liocranidae, Miturgidae, Oxyopidae, Pholcidae, Porrhothelidae, Salticidae, Selenopidae, Sicariidae, Sparassidae, Tetragnathidae, and Thomisidae) might be considered as chance events that took place when a tiny vertebrate crossed the path of an opportunistic spider. For a few families (e.g., Idiopidae) their status as habitual or occasional vertebrate predators is still unclear. In conclusion, our survey unveiled a large number of spider taxa previously not anticipated to feed on vertebrate prey. These findings improve our general understanding of spider feeding ecology and provide a first assessment of the significance of vertebrate prey as a food source for spiders.

Keywords: Araneae - predator diversity - vertebrate prey - prey-capture adaptations - physical strength - toxins - silk tensile strength

2021  Spiders (Arachnida: Araneae) feeding on snakes (Reptilia: Squamata) — Nyffeler M & Gibbons JW — Journal of Arachnology 49: 1–27   doi> 10.1636/JoA-S-20-050 

In this paper, 319 incidents of snake predation by spiders are reported based on a comprehensive global literature and social media survey. Snake-catching spiders have been documented from all continents except Antarctica. Snake predation by spiders has been most frequently documented in USA (51% of all incidents) and Australia (29%). The captured snakes are predominantly small-sized with an average body length of 25.9 6 1.3 cm (median 1_4 27 cm; range: 5.8–100 cm). Altogether .90 snake species from seven families have been documented to be captured by .40 spider species from 11 families. About 60% of the reported incidents were attributable to theridiids (’0.6–1.1 cm body length), a spider family that uses strong tangle webs for prey capture. Especially the Australian redback spider (Latrodectus hasselti Thorell, 1870), the African button spider (Latrodectus indistinctus O. Pickard-Cambridge, 1904), an Israeli widow spider (Latrodectus revivensis Shulov, 1948), and four species of North American widow spiders (Latrodectus geometricus C.L. Koch, 1841, Latrodectus hesperus Chamberlin & Ivie, 1935, Latrodectus mactans (Fabricius, 1775), and Latrodectus variolus Walckenaer, 1837) – equipped with a very potent vertebrate-specific toxin (a- latrotoxin) – have proven to be expert snake catchers. The use of vertebrates as a supplementary food source by spiders represents an opportunity to enlarge their food base, resulting in enhanced survival capability. Interestingly, the snakes captured by spiders also encompasses some species from the families Elapidae and Viperidae known to be highly toxic to humans and other vertebrates. Not only do spiders sometimes capture and kill snakes, quite often the tables are turned – that is, a larger number of arthropod-eating snake species (in particular nonvenomous species in the family Colubridae) include spiders in their diets.

Keywords: Araneae - Serpentes - black widow - Latrodectus - Theraphosidae - predation - intraguild predation - venomous spiders - venomous snakes

2021  Vertebrate-eating jumping spiders (Araneae: Salticidae) revisited: consumption of geckos and bird hatchlings — Nyffeler M, Edwards GB & Arkin R — Journal of Arachnology 49: 397–401   doi> 10.1636/JoA-S-20-090 

n this paper, vertebrate predation by jumping spiders (Salticidae) was revisited, taking into account incidents of this kind recently published in the scientific literature or on the internet. Our study revealed that vertebrate predation by salticids is more widespread than previously thought, geographically and taxonomically. Roughly ninety percent of all reported cases refer to predation on anurans (Hylidae and Ranixalidae) and lizards (Dactyloidae and Gekkonidae) by salticids from the subfamily Salticinae (Hyllus spp., Phidippus spp., and an unidentified species presumably related to Hasarius Simon, 1871). In the remaining cases, salticids from the subfamily Salticinae (Paraphidippus cf. aurantius (Lucas, 1833) and Phidippus audax (Hentz, 1845)) were observed attacking bird hatchlings (families Paridae and Trochilidae), weighing ’4–6 times more than the spiders. In two instances, the spiders were observed biting the hatchlings, but only in one single case, a salticid was seen feeding on a hatchling.

Keywords: Large salticids - predation - Dactyloidae - Gekkonidae - Hylidae - Ranixalidae - bird hatchlings

2020  Spiders as frog-eaters: a global perspective — Nyffeler M & Altig R — Journal of Arachnology 48: 26–42   doi> 10.1636/0161-8202-48.1.26 
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In this paper 374 incidents of frog predation by spiders are reported based on a comprehensive global literature and social media survey. Frog-catching spiders have been documented from all continents except for Antarctica (>80% of the incidents occurring in the warmer areas between latitude 30° N and 30° S). Frog predation by spiders has been most frequently documented in the Neotropics, with particular concentration in the Central American and Amazon rain forests and the Brazilian Atlantic forest. The captured frogs are predominantly small-sized with an average body length of 2.76 ± 0.13 cm (usually ≈0.2–3.8 g body mass). All stages (eggs/embryos, hatchlings, tadpoles, emerging metamorphs, immature post-metamorphs, adults) of the frogs’ life cycle are vulnerable to spider predation. The majority (85%) of the 374 reported incidents of frog predation were attributable to web-less hunting spiders (in particular from the superfamilies Ctenoidea and Lycosoidea) which kill frogs by injection of powerful neurotoxins. The frog-catching spiders are predominantly nocturnal with an average body length of 2.24 ± 0.12 cm (usually ≈0.1–2.7 g body mass). Altogether >200 frog species from 32 families (including several species of bitter tasting dart-poison frogs) have been documented to be hunted by >100 spider species from 22 families. Our finding that such a high diversity of spider taxa is utilizing such a high variety of frog taxa as prey is novel. The utilization of frogs as supplementary food increases the spiders’ food supply (i.e., large diet breadth), and this is presumed to enhance their chance of survival. Studies from Australia and South America indicate that frogs might be a substantial component in the diet of some mygalomorph spiders (i.e., families Atracidae, Idiopidae, and Theraphosidae). Many more quantitative investigations on the natural diets of tropical spiders are needed before reliable conclusions on the importance of frogs as spider food can be drawn.

Keywords: Araneae - Anura - predation - dart-poison frogs - nutritional importance - survival capability

2020  Where have all the spiders gone? Observations of a dramatic population density decline in the once very abundant garden spider, Araneus diadematus (Araneae: Araneidae), in the Swiss midland — Nyffeler M & Bonte D — Insects 11: 248–   doi> 10.3390/insects11040248 
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Aerial web-spinning spiders (including large orb-weavers), as a group, depend almost entirely on flying insects as a food source. The recent widespread loss of flying insects across large parts of western Europe, in terms of both diversity and biomass, can therefore be anticipated to have a drastic negative impact on the survival and abundance of this type of spider. To test the putative importance of such a hitherto neglected trophic cascade, a survey of population densities of the European garden spider Araneus diadematus—a large orb-weaving species—was conducted in the late summer of 2019 at twenty sites in the Swiss midland. The data from this survey were compared with published population densities for this species from the previous century. The study verified the above-mentioned hypothesis that this spider’s present-day overall mean population density has declined alarmingly to densities much lower than can be expected from normal population fluctuations (0.7% of the historical values). Review of other available records suggested that this pattern is widespread and not restricted to this region. In conclusion, the decline of this once so abundant spider in the Swiss midland is evidently revealing a bottom-up trophic cascade in response to the widespread loss of flying insect prey in recent decades

Keywords: bottom-up trophic cascade - low abundance - orb-weaving spiders - prey scarcity - western European landscape

2018  Insectivorous birds consume an estimated 400-500 million tons of prey annually — Nyffeler M, Şekercioğlu CH & Whelan CJ — The Science of Nature 105: 47–   doi> 10.1007/s00114-018-1571-z 
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In this paper, we present an estimate of the predation impact of the global population of insectivorous birds based on 103 (for the most part) published studies of prey consumption (kg ha-1 season-1) of insectivorous birds in seven biome types. By extrapolation—taking into account the global land cover of the various biomes—an estimate of the annual prey consumption of the world’s insectivorous birds was obtained. We estimate the prey biomass consumed by the world’s insectivorous birds to be somewhere between 400 and 500 million metric tons year-1, but most likely at the lower end of this range (corresponding to an energy consumption of ≈ 2.7 × 1018 J year-1 or ≈ 0.15% of the global terrestrial net primary production). Birds in forests account for > 70% of the global annual prey consumption of insectivorous birds (≥ 300 million tons year-1), whereas birds in other biomes (savannas and grasslands, croplands, deserts, and Arctic tundra) are less significant contributors (≥ 100 million tons year-1). Especially during the breeding season, when adult birds feed their nestlings protein-rich prey, large numbers of herbivorous insects (i.e., primarily in the orders Coleoptera, Diptera, Hemiptera, Hymenoptera, Lepidoptera, and Orthoptera) supplemented by spiders are captured. The estimates presented in this paper emphasize the ecological and economic importance of insectivorous birds in suppressing potentially harmful insect pests on a global scale—especially in forested areas.

Keywords: arthropods - avifauna - breeding season - global impact - insect pests - predation

2018  Black widow spiders, Latrodectus spp., (Araneae: Theridiidae) and other spiders feeding on mammals — Nyffeler M & Vetter RS — Journal of Arachnology 46: 541–548   doi> 10.1636/JoA-S-18-026.1 
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A survey of reports on spiders preying on small, non-flying mammals (i.e., mice, deer mice, voles, rats, heteromyid rodents, shrews) published in the literature and in the social media yielded a total of 42 naturally occurring incidents. Spiders from five families (Agelenidae, Ctenidae, Sparassidae, Theraphosidae, and Theridiidae) were reported capturing small mammals under natural conditions. Additionally, spiders from four more families (Atracidae, Lycosidae, Pisauridae, and Porrhothelidae) are known to kill small mammals in captivity. Approximately 80% of the reported incidents were attributable to theridiid spiders, especially the Australian redback spider (Latrodectus hasselti Thorell, 1870) and three species of North American widow spiders (Latrodectus geometricus C.L. Koch, 1841, Latrodectus hesperus Chamberlin & Ivie, 1935, and Latrodectus mactans (Fabricius, 1775)) have been shown to be expert mice catchers. The success of widow spiders in subduing small mammals can be explained by their ability to spin strong webs made up of tough silk, and producing a very potent toxin (_-latrotoxin) specifically targeting the vertebrate nervous system.

2017  An estimated 400–800 million tons of prey are annually killed by the global spider community — Nyffeler M & Birkhofer K — The Science of Nature 104: 30–   doi> 10.1007/s00114-017-1440-1 
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Spiders have been suspected to be one of the most important groups of natural enemies of insects worldwide. To document the impact of the global spider community as insect predators, we present estimates of the biomass of annually killed insect prey. Our estimates assessed with two different methods suggest that the annual prey kill of the global spider community is in the range of 400–800 million metric tons (fresh weight), with insects and collembolans composing >90% of the captured prey. This equals approximately 1‰ of the global terrestrial net primary production. Spiders associated with forests and grasslands account for >95% of the annual prey kill of the global spider community, whereas spiders in other habitats are rather insignificant contributors over a full year. The spider communities associated with annual crops contribute less than 2% to the global annual prey kill. This, however, can be partly explained by the fact that annual crop fields are “disturbed habitats” with a low buildup of spider biomass and that agrobiont spiders often only kill prey over short time periods in a year. Our estimates are supported by the published results of exclusion experiments, showing that the number of herbivorous/detritivorous insects and collembolans increased significantly after spider removal from experimental plots. The presented estimates of the global annual prey kill and the relative contribution of spider predation in different biomes improve the general understanding of spider ecology and provide a first assessment of the global impact of this very important predator group.

Keywords: Araneae - Collembola - insects - global impact - predation

2017  Bird predation by praying mantises: a global perspective — Nyffeler M, Maxwell MR & Remsen J V  — The Wilson Journal of Ornithology 129: 331–344   doi> 10.1676/16-100.1 
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We review 147 incidents of the capture of small birds by mantids (order Mantodea, family Mantidae). This has been documented in 13 different countries, on all continents except Antarctica. We found records of predation on birds by 12 mantid species (in the genera Coptopteryx, Hierodula, Mantis, Miomantis, Polyspilota, Sphodromantis, Stagmatoptera, Stagmomantis, and Tenodera). Small birds in the orders Apodiformes and Passeriformes, representing 24 identified species from 14 families (Acanthizidae, Acrocephalidae, Certhiidae, Estrildidae, Maluridae, Meliphagidae, Muscicapidae, Nectariniidae, Parulidae, Phylloscopidae, Scotocercidae, Trochilidae, Tyrannidae, and Vireonidae), were found as prey. Most reports (>70% of observed incidents) are from the USA, where mantids have often been seen capturing hummingbirds attracted to food sources in gardens, i.e., hummingbird feeders or hummingbird-pollinated plants. The Ruby-throated Hummingbird (Archilochus colubris) was the species most frequently reported to be captured by mantids. Captures were reported also from Canada, Central America, and South America. In Africa, Asia, Australia, and Europe, we found 29 records of small passerine birds captured by mantids. Of the birds captured, 78% were killed and eaten by the mantids, 2% succeeded in escaping on their own, and 18% were freed by humans. In North America, native and non-native mantids were engaged in bird predation. Our compilation suggests that praying mantises frequently prey on hummingbirds in gardens in North America; therefore, we suggest caution in use of large-sized mantids, particularly non-native mantids, in gardens for insect pest control.

Keywords: gardens - hummingbird feeders - Mantidae - natural enemy - Passeriformes - Trochilidae

2017  A vertebrate-eating jumping spider (Araneae: Salticidae) from Florida, USA — Nyffeler M, Edwards GB & Krysko KL — Journal of Arachnology 45: 238–241   doi> 10.1636/JoA-17-011.1 
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The salticid spider Phidippus regius C.L. Koch, 1846 is documented preying on small frogs (Hyla spp., Osteopilus septentrionalis) and lizards (Anolis carolinensis and Anolis sagrei) in Florida, USA. Female as well as male P. regius were engaged in feeding on this type of vertebrate prey. A total of eight incidents of P. regius devouring vertebrates have been witnessed in seven Florida counties. Furthermore, we report an incident of a large unidentified Phidippus sp. (possibly P. bidentatus F. O. Pickard-Cambridge, 1901) preying on an immature anole lizard in Costa Rica. P. regius, otherwise known to feed almost exclusively on insects and spiders, is one of the world’s largest salticid spiders reaching a maximum recorded body length of 2.2 cm. Most other salticid spiders appear to be too small in body size to overcome vertebrate prey. Vertebrate predation by salticid spiders has not been previously documented in the scientific literature. Together with Salticidae, spiders from 27 of 114 families (24%) are currently known to occasionally consume vertebrate prey.

Keywords: generalist predators - predation - prey - Dactyloidae - Hylidae - Southeastern USA

2017  Spiders feeding on earthworms revisited: consumption of giant earthworms in the tropics — Nyffeler M, Lapinski W, Snyder A & Birkhofer K — Journal of Arachnology 45: 242–247   doi> 10.1636/JoA-17-013.1 
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Predation on earthworms is common in some generalist predator species, as for example several ground beetle species (Coleoptera: Carabidae) that frequently feed on earthworms. In spiders (Araneae), however, such behavior is far less well documented. A survey of reports on spiders feeding on earthworms yielded a total of 44 naturally occurring predation events. Spiders from 14 families were observed feeding on earthworms in nature, and species from two additional families consumed earthworm prey in captivity. Earthworm predation by spiders has been observed in temperate, subtropical, and tropical regions in 18 different countries. Tropical spiders from the families Theraphosidae (Mygalomorphae) and Ctenidae (Araneomorphae) accounted for 59% of the reported predation events. Reports from French Guiana document the capture of giant earthworms (0.6–1 m in length) by the giant tarantula, Theraphosa blondi (Latreille, 1804). Predation on giant earthworms by large tarantulas has also been observed in rainforest habitats in Brazil, Ecuador, Peru, and Venezuela. Wandering spiders (Ctenidae) are known to feed on earthworms in Belize, Brazil, Costa Rica, French Guiana, Guyana, and Singapore. Quite obviously, larger-sized mygalomorph and araneomorph spiders in humid tropical rainforests are predators with broad feeding niches—including earthworms and vertebrate prey in addition to arthropod prey—and this is presumed to improve the survival of these spiders. By comparison, reports of earthworm predation in temperate climate are rarer, and recent molecular studies of the diet composition of lycosid and linyphiid spider species in Swedish arable fields suggest that earthworms are not a common prey of these species.

Keywords: Oligochaeta - Ctenidae - Theraphosidae - generalist predators - diet composition

2017  Birds as prey for praying mantises: observations from around the world — Nyffeler M — Natural History 125: 14–17
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2016  Plant-eating by spiders — Nyffeler M, Olson EJ & Symondson WOC — Journal of Arachnology 44: 15–27   doi> 10.1636/P15-45.1 
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Spiders, a group of predominantly insectivorous predators, occasionally use plant food to supplement their insect prey. In the current review, we tracked down 95 reported incidents of spiders feeding on plant food under natural conditions. Globally, >60 spider species representing ten families have been observed feeding on plant materials from over 20 plant families. Cursorial spiders including the families Anyphaenidae, Clubionidae, Eutichuridae, Salticidae, Thomisidae, and Trachelidae dominate among the spiders feeding on plant food (>80% of reported incidents). Spiders feed on a wide diversity of plant-derived products including floral nectar, extrafloral nectar, stigmatic exudate, plant sap, honeydew, seeds, Beltian bodies, Mu_llerian bodies and pollen (originating from very different plant types such as coniferous and deciduous trees, herbaceous plants and shrubs, annual weeds, grasses, climbing plants, orchids, carnivorous plants, and ferns). Furthermore, spiders have been shown to consume fungal spores in laboratory trials. Supplementary feeding on plant materials by spiders was shown to be global in extent and widespread across spider taxa, plant taxa and plant materials; however, the extent to which the different categories of plant food contribute to the spiders’ diet and how this may affect their behavior and life history is still largely unexplored. This review is expected to lay a foundation for future research on this topic.

Keywords: food bodies - honeydew - nectar - nutritional ecology - plant-derived food - pollen

2016  Phytophagy in jumping spiders: The vegetarian side of a group of insectivorous predators — Nyffeler M — Peckhamia: 137.1–
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Jumping spiders (Salticidae), a group of predominantly insectivorous predators, occasionally supplement their insect prey by deriving nutrients from plant food (‘facultative phytophagy’). The aim of this paper is to give a brief overview of the plant eating activities of salticids based on the published literature. Plant-eating by salticids has been reported from all continents except Antarctica and Europe. With regard to Antarctica it must be said that salticid spiders are absent from there. The previous lack of observations from Europe, on the other hand, may be explained by the fact that plant-eating by salticids is typically found in the warmer areas of the globe (_ 40° latitude) and because most of Europe is located in colder climates (> 40° latitude), it comes as no big surprise that this type of feeding has not yet been detected in European salticids. In order to exploit plant food resources, salticid spiders have to overcome various hurdles. Firstly, plant products such as floral nectar and pollen, serving to attract pollinators, might be chemically protected to deter nectar robbers and pollen thieves. Defensive chemicals such as alkaloids and cardenolides, if ingested along with plant food, may alter the spiders’ behavior as has been demonstrated in laboratory experiments with non-salticid spiders. Whether such behavior-altering chemicals have also an effect on free-living salticid spiders, remains to be researched. Secondly, plant-derived foods such as extrafloral nectar, Beltian bodies or coccid honeydew are aggressively defended by ant bodyguards and spiders must break through the ant defenses in order to get access to these types of food. Salticids detect ants by sight and are able to actively avoid them in most cases. Another situation does occur when the approaching salticid is an ant-mimic perceived by ants as ant (e.g., genus Myrmarachne or Peckhamia); ant-mimicking salticids appear to have unhindered access to plant-derived foods such as extrafloral nectar or coccid honeydew. Thirdly, spiders (adapted to eat insect prey) might require some specific enzymes enabling them to chemically break down plant materials. Currently it seems to be well understood how spiders accomplish the digestion of liquid plant food, whereas the process of digesting solid plant tissue is not yet completely investigated. As in other predaceous arthropods, the ability of spiders to derive nutrients from plant materials is broadening these animals’ diet which may have survival value during periods of prey scarcity.

Keywords: ant bodyguards - ant-mimics - defensive chemicals - facultative phytophagy - geographic distribution - plant food - Salticidae

2014  Fish predation by semi-aquatic spiders: a global pattern — Nyffeler M & Pusey BJ — PLOS ONE 9: e99459–   doi> 10.1371/journal.pone.0099459 
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More than 80 incidences of fish predation by semi-aquatic spiders – observed at the fringes of shallow freshwater streams, rivers, lakes, ponds, swamps, and fens – are reviewed. We provide evidence that fish predation by semi-aquatic spiders is geographically widespread, occurring on all continents except Antarctica. Fish predation by spiders appears to be more common in warmer areas between 40° S and 40° N. The fish captured by spiders, usually ranging from 2–6 cm in length, are among the most common fish taxa occurring in their respective geographic area (e.g., mosquitofish [Gambusia spp.] in the southeastern USA, fish of the order Characiformes in the Neotropics, killifish [Aphyosemion spp.] in Central and West Africa, as well as Australian native fish of the genera Galaxias, Melanotaenia, and Pseudomugil). Naturally occurring fish predation has been witnessed in more than a dozen spider species from the superfamily Lycosoidea (families Pisauridae, Trechaleidae, and Lycosidae), in two species of the superfamily Ctenoidea (family Ctenidae), and in one species of the superfamily Corinnoidea (family Liocranidae). The majority of reports on fish predation by spiders referred to pisaurid spiders of the genera Dolomedes and Nilus (>75% of observed incidences). There is laboratory evidence that spiders from several more families (e.g., the water spider Argyroneta aquatica [Cybaeidae], the intertidal spider Desis marina [Desidae], and the ‘swimming’ huntsman spider Heteropoda natans [Sparassidae]) predate fish as well. Our finding of such a large diversity of spider families being engaged in fish predation is novel. Semi-aquatic spiders captured fish whose body length exceeded the spiders’ body length (the captured fish being, on average, 2.2 times as long as the spiders). Evidence suggests that fish prey might be an occasional prey item of substantial nutritional importance.

2013  Bat predation by spiders — Nyffeler M & Knörnschild M — PLOS ONE 8: e58120–   doi> 10.1371/journal.pone.0058120 
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In this paper more than 50 incidences of bats being captured by spiders are reviewed. Bat-catching spiders have been reported from virtually every continent with the exception of Antarctica (≈90% of the incidences occurring in the warmer areas of the globe between latitude 30° N and 30° S). Most reports refer to the Neotropics (42% of observed incidences), Asia (28.8%), and Australia-Papua New Guinea (13.5%). Bat-catching spiders belong to the mygalomorph family Theraphosidae and the araneomorph families Nephilidae, Araneidae, and Sparassidae. In addition to this, an attack attempt by a large araneomorph hunting spider of the family Pisauridae on an immature bat was witnessed. Eighty-eight percent of the reported incidences of bat catches were attributable to web-building spiders and 12% to hunting spiders. Large tropical orb-weavers of the genera Nephila and Eriophora in particular have been observed catching bats in their huge, strong orb- webs (of up to 1.5 m diameter). The majority of identifiable captured bats were small aerial insectivorous bats, belonging to the families Vespertilionidae (64%) and Emballonuridae (22%) and usually being among the most common bat species in their respective geographic area. While in some instances bats entangled in spider webs may have died of exhaustion, starvation, dehydration, and/or hyperthermia (i.e., non-predation death), there were numerous other instances where spiders were seen actively attacking, killing, and eating the captured bats (i.e., predation). This evidence suggests that spider predation on flying vertebrates is more widespread than previously assumed.

2009  Estimate of the daily catch of prey of the orb-weaving spider Argiope bruennichi (SCOPOLI) in the field: original data and minireview — Nyffeler M — Contributions to Natural History Konrad Thaler Memorial Volume: 1007–1020
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Prey capture by the large orb-weaving spider Argiope bruennichi (SCOPOLI) (Araneidae) was investigated in uncut grassland (heavily infested with flowering weeds and shrubs) in the outskirts of Zurich, Switzerland, on three consecutive days in early August (between 09:00 and 18:00 hours). A. bruennichi was found to be a predominantly diurnal predator of larger-sized grassland insects (Hymenoptera and Orthoptera composing approx. 90% of the total prey biomass). On average, 38% of the encountered spiders were feeding. It is estimated that adult female A. bruennichi captured, on average, approx. 90 mg (fresh weight) prey web-1 day-1, which is the equivalent of the weight of a worker honey bee. My results were compared with the published estimates of other researchers.

Keywords: orb-weaving spider - Argiope bruennichi - Araneidae - feeding frequency - prey capture rate - uncut grassland - Zurich - Switzerland

2003  Composition, abundance and pest control potential of spider communities in agroecosystems: a comparison of European and US studies — Nyffeler M & Sunderland KD — Agriculture, Ecosystems & Environment 95: 579–612   doi> 10.1016/S0167-8809(02)00181-0 
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Current knowledge of spiders in agroecosystems (excluding tree crops) reported in European and US literature is discussed comparatively, in an attempt to relate spider community structure to pest control potential.
The spider fauna of agroecosystems in the northern-temperate zone of Europe is strongly dominated by small linyphiid spiders that capture tiny insects in their sheet webs, including large numbers of pest aphids. In the US, spider guild structure is more complex, and hunters (especially, Oxyopidae, Salticidae, Clubionidae, Thomisidae, and Lycosidae), that have broader diets (including lepidopteran and heteropteran pests), numerically prevail in many locations. Spider populations increase to high densities (2-600 m²) in European field crops, but densities are typically much lower (0.02-14 m²) in US annual crops. Agroecosystem spiders, in both Europe and the US, feed rather infrequently, but they contribute to pest control as part of larger assemblages of natural enemies, and there is potential for increasing their density and impact in both continents.
Many of the differences between continents in spider guild structure, density and feeding patterns highlighted in this paper are likely to be attributable to climatic differences. Most of the US data originate from more southern latitudes (i.e., subtropical and Mediterranean climates) with distinctly higher mean annual temperatures compared to the European study areas, which are in the northern-temperate zone. Spider communities may respond to climate directly, and also indirectly via food availability and antagonists. In addition, differences in crop structure and cultural practices (including habitat diversification and the provision of ground cover) could influence spider density and community organisation. Mean farm size is an order of magnitude less in Europe than in the US and this is likely to be associated with greater habitat diversity, which is known to increase spider abundance.
Currently, there is a dearth of field studies from southern Europe (Mediterranean climate) and the northern regions of the US (humid continental climate). The few data available from such regions indicate that the patterns of spider predation may differ less between the two continents if sufficient study areas with similar climatic conditions could be compared. The conclusions in terms of biological control are, however, widely applicable, because a large proportion of the productive agricultural land area of Europe is located in more northern latitudes and the reverse is true in the US.

Keywords: review - agroecosystem - biological control - ecology - Araneae - Linyphiidae - North America - biodiversity - distribution - abundance - diets - prey - latitude - temperature

2001  Spiders and harvestmen as gastropod predators — Nyffeler M & Symondson WOC — Ecological Entomology 26: 617–628   doi> 10.1046/j.1365-2311.2001.00365.x 

1. Reports are reviewed of gastropod feeding (malacophagy) by spiders and harvestmen. Although the standard textbooks on arachnids recognise the importance of gastropods as prey of harvestmen, none apparently refers to malacophagy by spiders. A review of several hundred papers on spider feeding habits revealed that species from several families kill and devour slugs and snails in the laboratory and/or field.
2. Malacophagy has been reported most frequently among mygalomorph spiders, and can make up a substantial proportion of the diets of some species, however gastropods make up an insignificant percentage of the prey of most araneomorph spiders. The spiders that eat gastropods are species with broad diets composed predominantly of arthropod prey. No species of spider appears to feed exclusively on gastropod prey.
3. Harvestmen from several families have broad diets that often include gastropods. Several species of the family Trogulidae and at least one species of the family Ischyropsalididae [Ischyropsalis hellwigi (Panzer)] are specialised gastropod predators. The trogulids are slender animals that attack the snail through the shell aperture (shell intruders). Ischyropsalis hellwigi, on the other hand, can crush snail shells with its powerful chelicerae (shell breakers).
4. The review highlights apparent convergent evolution by harvestmen and Carabidae of two mutually exclusive morphologies found among gastropod predators. It also suggests that there is an urgent need for systematic studies to be conducted to establish the extent and ecological importance of malacophagy in natural and anthropogenically altered habitats.

Keywords: Araneae - convergent evolution - foraging behaviour - malacophagy - Opiliones - prey choice - slug - snail

2001  Spiders feeding on earthworms — Nyffeler M, Moor H & Foelix RF — Journal of Arachnology 29: 119–124   doi> 10.1636/0161-8202(2001)029[0119:SFOE]2.0.CO;2 
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American Arachnological Society)

A house spider (Tegenaria atrica C.L. Koch 1843, Agelenidae) was observed, filmed and photographed while feeding on an earthworm. An extensive search in the literature revealed that several arachnologists had noted spiders feeding on earthworms, altogether in 11 different families. Earthworm-eating spiders belong mostly to larger sized species dwelling near the ground in woodlands and grasslands. Since earthworms have a high protein content, they could be a welcome supplement to the spider's usual insect diet.

2000  Ecological impact of spider predation: a critical assessment of Bristowe's and Turnbull's estimates — Nyffeler M — Bulletin of the British Arachnological Society 11: 367–373
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British Arachnological Society)

Decades ago, Bristowe (1939, 1947, 1958) and Turnbull (1973) tried to quantify the ecological impact of spider predation upon insect populations by means of extrapolations. Both came to the conclusion that spiders, occurring in high numbers, would kill astronomical quantities of insects. Bristowe's and Turnbull's density and prey kill estimates have been quoted frequently in the arachnological literature; however, they have never been proven true or false. In this paper, these estimates are critically analysed in the light of current knowledge of spider ecology. Bristowe estimated that the annual prey kill of all British spiders would exceed the combined weight of all humans in Britain (which he assessed at ≈ 80 kg ha-1). However, more recent comprehensive studies conducted on agricultural land have resulted in distinctly lower prey kill values ≈ 1-40 kg ha-1 yr-1). Since Great Britain consists predominantly of agricultural land, it follows that Bristowe probably over-estimated the overall mean prey kill of the spiders. Turnbull's hypothetical calculation (based on a very high assumed average food consumption) resulted in a prey kill value of 42,500 kg ha-1 yr-1; this latter value is of the same magnitude as the net primary production, which is irreconcilable with ecological theory.

2000  Do adult female lycosids feed during the period of maternal care? — Nyffeler M — Bulletin of the British Arachnological Society 11: 388–390
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British Arachnological Society)

It has been stated in some literature reports that in the highly cannibalistic wolf spiders (Lycosidae) the adult females do not feed while engaged in maternal care (i.e. their predatory behaviour is inhibited), whereas other reports based on laboratory studies indicate that maternal females resume feeding. During a two-year field study on the feeding habits of the wolf spiders Pardosa agrestis, P. palustris and P. amentata, I had the opportunity to investigate the question whether in these species maternal females do feed (or not). Overall, 25 instances of wolf spider mothers feeding during the period of maternal care are reported. Eighteen cases refer to egg sac-carrying females, 7 cases to pulli-carrying females. It must be stated, however, that the feeding rate of maternal females was significantly lower than that of non-maternal females, which is in agreement with the findings of other researchers obtained in the laboratory. It is hypothesised that there may be genusspecific behavioural differences between free-moving and burrowing wolf spider species which may (at least in part) explain the apparent discrepancies between the reports of various authors.

2000  Killing power of the orb-weaving spider Argiope bruennichi (Scopoli, 1772) during a mass occurrence — Nyffeler M — Newsletter of the British Arachnological Society 89: 11–12
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British Arachnological Society)

1999  Prey selection of spiders in the field — Nyffeler M — Journal of Arachnology 27: 317–324
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American Arachnological Society)

In this article, an overview of the general feeding patterns of common agroecosystem spiders is presented. Five groups of web-weavers (Tetragnathidae, Araneidae, Theridiidae, Linyphiidae, Dictynidae) and five groups of hunters (small-sized Oxyopidae, large-sized Oxyopidae, Thomisidae, Salticidae, Lycosidae) are analyzed comparatively (based on 40 prey analyses previously published by various European and US authors). Fewer than 10 insect orders, as well as the order Araneae, make up the bulk of the prey of these spiders. Web-weavers and hunters both basically feed on the same prey orders, but in different proportions. The observed differences reflect in part the very diverse range of life styles and foraging modes exhibited by the various spider groups and, to some extent, differences in prey availability. Web-weavers are almost strictly insectivorous (insects constituting >99% of total prey). Hunters, however, exhibit a mixed strategy of insectivorous and araneophagic foraging patterns (insects constituting 75-90% of total prey). Diet breadth computed with the Inverted Simpson Index was, on average, significantly higher in the hunting spiders than the web spiders. There seems to be a consistent trend of greater diet breadth of the hunters compared to the web-weavers in agroecosystems. Overall, spider individuals of small size (including large percentages of immatures) numerically dominate the faunas of field crops, and these feed primarily on tiny prey (<4 mm in length).

1998  Einfluss der Bewirtschaftung auf Wiesenspinnen: Stress im grünen Gras — Nyffeler M — Ornis 5/1998: 4–9
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Mahd und Düngung führen dazu, dass die Spinnenfauna in Fettwiesen verarmt - nur stressresistente Arten vermögen eine solch intensive Nutzung auszuhalten. Anders in blumenreichen Extensivwiesen: das Spinnenleben überquillt, und Wiesenvögel finden einen gedeckten Tisch. Was geht in der Welt der Spinnen vor, wenn Wiesen gemäht werden?

1996  Spiders as biological control agents in cotton plantations in Texas — Nyffeler M — Habilitation thesis, Faculty of Science, University of Bern, Switzerland, 83 pp.
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The ecological impact of spider predation on cotton insects in cotton fields in Texas was investigated. In particular, it was assessed how frequently the spiders feed on four 'key pests' of Texas cotton (i.e., cotton fleahopper Pseudatomoscelis seriatus [Heteroptera: Miridae], boll weevil Anthonomus grandis grandis [Coleoptera: Curculionidae], bollworm Helicoverpa zea [=Heliothis zeal] [Lepidoptera: Noctuidae], and tobacco budworm Heliothis virescens [Lepidoptera: Noctuidae]) and to what extent this may impact the mortality of these pests. The data were collected over a period of totally ≈ 200 h of visual observations in the course of two field projects: The first project was conducted during the summer of 1985 in an unsprayed (6.5 ha) cotton plantation near Austonio, Houston County, East Texas. The second project was undertaken during the summer of 1988 in an unsprayed (13.6 ha) cotton plantation located near Snook, Burleson County, Central Texas, approximately 100 km southwest of the previous study site.
The spider assemblages found in cotton in Austonio and Snook were quite similar and represent a species complex typical for extensive cotton growing areas throughout the U.S. cotton belt, with lynx spiders (Oxyopidae) numerically predominating. Lynx spiders consistently constituted > 50% of the spider total throughout the growing season. The second most abundant spider group, the orb-weavers (Araneidae and Tetragnathidae), constituted ≈ 10% of the spider total. Two species of lynx spiders occur in these fields: the 'striped lynx' Oxyopes salticus and the 'green lynx' Peucetia viridans. The numerically dominant Oxyopes occurred in average densities of ≈ 1-1.5/m² during mid-season in both plantations. [Peucetia is less frequently found in cotton and is therefore expected to be of minor importance as a potential natural enemy of pests in the cotton fields. ] The studies focussed primarily on the numerically dominant lynx spiders and orb-weavers.
To evaluate the predatory significance of the lynx spiders relative to the other predaceous arthropods occurring in cotton, the total number of predation events observed attributable to lynx spiders versus other arthropod predators was compared based on the data which had been collected in Snook. A total of 134 arthropod predators with prey in their chelicerae/mandibulae were monitored during the 108 h observation period, which included 94 lynx spiders versus 40 other predators. Thus, 70% of all predation events observed were attributable to lynx spiders which indicates that these spiders were the dominant predators in this cotton plantation. Similar patterns of a predominance of lynx spider predation were observed in Austonio, too.
The predation rate (: no. prey killed/spider/day) was estimated with a visual method based on average feeding frequency (percentage spiders with prey in their chelicerae) observed in the field, average handling time, and hunting (searching) time; it was estimated that a subadult/adult Oxyopes (representing a typical agroecosystem spider) may capture ≈ 1 prey organism on an average rainfree day in the field (during the middle of the growing season). The same spiders feed at several times higher rates in laboratory feeding experiments if food is offered ad libitum (as is known from literature), which suggests that in the field these spiders often feed below their maximum feeding capacity. Thus, the spiders can be expected to increase their predation rate during severe outbreaks of insect pests (i.e., 'functional response').
The majority of the lynx spiders in cotton were of small size (i.e., Oxyopes). Oxyopes captures a wide variety of small-sized arthropods ranging from 0.6 to 6 mm length ( ≈ 2.5 mm optimal prey length). [ In contrast to this, the larger Peucetia feeds over a broader range of prey size classes and consequently captures a higher proportion of the larger prey organisms, but because this species is much less abundant than Oxyopes, its contribution to the overall predation impact is rather low. ] Likewise, most orb-weavers occurring in cotton were of small body size. Overall, spider individuals of small size (including large percentages of immatures) numerically dominate the faunas of the investigated cotton fields, and these spiders feed primarily on tiny prey organisms (≤ 3 mm in length).
With a body length range of 1.1-2.9 mm (third instar to adult) cotton fleahoppers ideally fit the optimal prey length of ≈ 2.5 mm for Oxyopes. [ Peucetia, that captures on the average significantly larger-sized prey than Oxyopes, seems to be less efficient in capturing fleahoppers.] Oxyopes shows considerable flexibility in switching its feeding patterns in response to prey availability. - In the cotton plantation in Austonio, the numbers of cotton fleahoppers were below the economic threshold, and consequently very low predation rates on fleahopper prey by spiders were observed (0% fleahoppers in the diet of Oxyopes); instead, Oxyopes fed heavily on red imported fire ants (22% of the diet) and other nonfleahopper prey. - A totally different scenario was observed in the cotton plantation in Snook, where cotton fleahoppers occurred in fairly high numbers; in this situation, Oxyopes fed heavily on these pests (fleahoppers constituting 24% of the diet). - These data indicate that Oxyopes may feed heavily on other predators such as fire ants when pests are rare; however, when pests become abundant this spider can largely switch to pestiferous species such as fleahoppers as a major food source.
The assessment of the killing power of Oxyopes, based on the predation rate and the predator-to-prey ratio (i.e., number of Oxyopes individuals per fleahopper), suggests that this spider contributes significantly to mortality of the cotton fleahopper (≥ 15% prey mortality per day, in the middle of the growing season) in the plantation in Snook; additional fleahopper mortality is attributable to other spiders and predaceous insects, though they are less effective than Oxyopes. - The other key pests (i.e., boll weevil, bollworm, and tobacco budworm) were poorly represented in the spider diets, which apparently reflects that these pests occurred in numbers far below economic injury levels (it is assumed that fire ants are the cause of the low pest levels). - The contribution of the spiders to fleahopper mortality, however, varies between the different fields and within different years, due to the spatial and temporal fluctuations of the numbers of spiders and fleahoppers. An approximately 30 times higher frequency of predation on fleahoppers was recorded in Snook compared to Austonio. Consequently the economic benefit due to these predators varies in different situations.
Based on population density counts in the cotton plantation in Austonio and the assessment of the predation rate, it was estimated that lynx spiders killed perhaps ≈ 0.6% of the potential prey per day in the middle of the growing season; it is assumed in the literature that mortality rates of that magnitude already have a significant positive impact on the community stability; thus, spiders can be considered to serve as 'stabilizing agents' (compare Turnbull, 1973, "Ecology of the true spiders", in: Annu. Rev. Entomol. 18, 305-348).

1994  Comparison of the feeding niche of polyphagous insectivores (Araneae) in a Texas cotton plantation - estimates of niche breadth and overlap — Nyffeler M & Sterling WL — Environmental Entomology 23: 1294–1303
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The feeding niches of 10 spider species that are polyphagous insectivores were compared by computing coefficients of niche breadth and niche overlap. The study is based on predation evidence from an insecticide-free cotton plantation in east Texas. All overlap values were < 1.00 (range, 0.08-0.94), which indicates that each spider species has its own feeding niche in the cotton agroecosystem. Diet breadth, that is inversely related to feeding specialization, was computed for each species. The highest value was approximately five times higher than the minimum, which indicates considerable differences between species in feeding specialization. Diet breadth values indicate that large web weavers exhibited a less specialized feeding behaviour (relatively broad feeding niche) compared with small web weavers (narrow feeding niche). Prey specialists in this study concentrated on either aphids or fire ants as a primary food source. The nonweb-building spider Oxyopes salticus Hentz, which actively searches the cotton plant for prey (up to almost-equal-to 6 mm maximum length), showed the highest diet breadth value (broad feeding niche) under the conditions of this experiment. This abundant species, which is considered a highly beneficial biocontrol agent of smaller cotton pests, shows high flexibility in its foraging patterns.

Keywords: insectivores - feeding niche - cotton

1994  How spiders make a living — Nyffeler M, Sterling WL & Dean DA — Environmental Entomology 23: 1357–1367
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Although the beneficial status of the spiders as insectivores has been widely recognized for quite some time, biologists by and large seem to be rather unfamiliar with the specific feeding habits of this very diverse order. We present an overview of the feeding patterns of 10 groups of common agroecosystem spiders to inform entomologists and ecologists concerned with issues of natural biological control. The various spider groups discussed in this article exhibit a very diverse range of life styles and foraging modes, which is reflected in the diversity of their feeding patterns. Implications of the insectivorous activities of these predators for natural pest control are discussed.

Keywords: spiders - predation - diets

1994  Insectivorous activities of spiders in United-States field crops — Nyffeler M, Sterling WL & Dean DA — Journal of Applied Entomology 118: 113–128

A survey of average spider numbers in U.S. field crops (considering a geographic range from the east to the west coast) gave an overall mean density of almost-equal-to 1 plant-dwelling spider/m² (+/- 0.18 SEM). This value is more than 100 times lower than TURNBULL's famous 'overall mean value' (= 130.8/m²) computed from 37 published censuses of spider numbers in a wide variety of environments from all over the world. Crop fields are disturbed systems whose spider numbers are drastically reduced by agricultural practices such as pesticide use, cultivation, harvest, etc. Small sized spider individuals (including large percentages of immatures) numerically dominate the faunas of U.S. field crops, and these feed primarily on tiny prey organisms (< 4 mm in length). Small web-building spiders are almost strictly insectivore (insects constituting > 99% of total prey). In contrast, the 'hunters' (nonweb-building spiders) that actively search the plant surface for prey, exhibit a mixed strategy of araneophagic and insectivorous foraging patterns (insects constituting less-than-or-equal-to 90% of total prey). The aggressive 'active searchers' are highly polyphagous (compared to the small web-weavers), but can narrow their feeding niche significantly when a suitable prey species reaches high numbers relative to other prey groups. The numerically dominant spider predators in U.S. field crops feed heavily on small plant-sucking insects such as plant bugs (Miridae), fleahoppers (Miridae), leafhoppers (Cicadellidae), treehoppers (Membracidae), planthoppers (Delphacidae), and aphids (Aphididae), which is of interest from a biocontrol point of view. A typical agroecosystem spider (i.e., striped lynx spider) may capture an average of almost-equal-to 1 prey per rainfree day in the field (by multiplying this value with the overall mean spider density of 1/m², it follows that the average prey kill may be in the order of magnitude of almost-equal-to 1 prey/m²/day). At prey densities of 100-300/m² (as recorded in literature), spiders kill perhaps almost-equal-to 0.3-1% of the potential prey per day. Extensive field and laboratory observations, experiments, and computer models conducted by research groups in different parts of the U.S. indicate that the collective predation impact of spiders may contribute significantly to lower pest levels in some crop fields.

1993  Biology, predation ecology, and significance of spiders in Texas cotton ecosystems with a key to the species — Breene RG, Dean DA, Nyffeler M & Edwards GB — Texas Agricultural Experiment Station Bulletin (College Station/USA) B-1711: 1–115
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(© Texas Agricultural Experiment Station, The Texas A&M University System, College Station, Texas)

Spiders aid in the control of cotton pest insects by direct predation and through incidental mortality (e. g., aphids adhering to a spider web and suffering mortality without spider intervention). Some spider species can be key predators (causing irreplaceable mortality to a pest species) of key insect pests such as the cotton fleahopper, Pseudatomoscelis seriatus (Reuter), a prey type for which spiders provide probably the most effective natural control. Most spider species serve as members of vast predator assemblages within cotton ecosystems, helping to restrict major and minor pests to low densities. Evidence suggests that arrays of spider species may act as ecological indicators of the degree to which pest insects are under control in cottonfields. Spider species have been observed feeding upon every major and most minor, secondary, or occasional insect pests of Texas cotton.
The discussion presented in this bulletin of pest categories and of appropriate corresponding biological control agents can help to unify the biological control concept for cotton and other agricultural crops. The three pest groups discussed consist of sessile external (SE) arthropod pests; sessile internal (SI) arthropod pests; and mobile, visually acute (MV) arthropod pests. Although spider predation influences all the groups to some degree, it is most effective against the MV category of pests.
A key and illustrations to all known species of spiders found on Texas cotton is provided to help in species identification. The known biology and predation ecology of each spider species found on Texas cotton is discussed both from the field experiences of the authors and from the literature.

Keywords: spiders - Araneae - taxonomy - biocontrol agent - cotton - Texas - identification key - predation ecology

1992  Diets, feeding specialization, and predatory role of 2 lynx spiders, Oxyopes salticus and Peucetia viridans (Araneae, Oxyopidae), in a Texas cotton agroecosystem — Nyffeler M, Dean DA & Sterling WL — Environmental Entomology 21: 1457–1465
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The predation ecology of the striped lynx spider, Oxyopes salticus Hentz, and green lynx spider, Peucetia viridans (Hentz), was studied during 108 h of visual observation in an insecticide-free cotton field in central Texas. Evidence obtained during this study indicates that lynx spiders were the dominant arthropod predators (among 134 cases of arthropod predation observed, 94 were attributable to lynx spiders). P. viridans is a powerful species (10.08 +/- 0.52 mm [mean +/- SEM] body length) compared with the significantly smaller O. salticus (4.24 +/- 0.16 mm). The O. salticus individuals fed on small-sized prey (2.41 +/- 0.17 mm average prey length). In contrast, the P. viridans individuals fed over a broader range of prey size classes and captured a higher proportion of the larger prey organisms (7.04 +/- 0.73 mm average prey length). However, the smallest P. viridans (less-than-or-equal-to 8 mm spider length) and the largest O. salticus (greater-than-or-equal-to 4.5 mm spider length) selected prey of similar average length (almost-equal-to 3 mm). The lynx spiders are polyphagous insectivores that feed on a variety of prey species predominantly in the insect orders Heteroptera, Hymenoptera, and Diptera. They also frequently eat other spiders. The most frequently captured prey of O. salticus were small Heteroptera (predominantly cotton fleahopper, Pseudatomoscelis seriatus [Reuter]), whereas P. viridans most frequently seized large stinging Hymenoptera (e.g., honey bee, Apis mellifera L.). The degree of the feeding specialization of the two spider species was mathematically assessed (niche breadth coefficients) and statistically compared; computed coefficients indicate that P. viridans is a significantly more polyphagous predator than the smaller-sized O. salticus. O. salticus, therefore, shows a better fit to the "model predator" of classical biological control because of its relative specialization.

Keywords: Lynx spiders - biological control - cotton

1992  Dominant insectivorous polyphagous predators in winter-wheat - high colonization power, spatial-dispersion patterns, and probable importance of the soil surface spiders (Araneae) — Nyffeler M & Breene RG — Deutsche Entomologische Zeitschrift 39: 177–188   doi> 10.1002/mmnd.19920390125 

Spiders inhabiting the soil surface of a winter wheat field were examined using pitfall traps near Zurich, central Europe. The soil surface spider community was dominated by two species of wolf Spiders Pardosa agrestis (WESTRING) and Pardosa palustris (L.) (Lycosidae) and three species of sheet-web weavers Erigone atra (BLACKWALL), Erigone dentipalpis (WIDER) and Oedothorax apicatus (BLACKWALL) (Linyphiidae). The identity and average number of spiders collected in the traps over time between field border and center were compared revealing that the number of wolf spiders on the border did not differ significantly from the center. However, the sheet-web weavers expressed a consistent trend of slightly greater numbers in the field's center compared to the border. Computation of the dispersion index (after MORISITA) indicates aggregated patterns throughout the field for both Lycosidae and Linyphiidae caught in the pitfall traps. The combined number of spider individuals showed an overall increase as the season progressed. Over 12000 spiders were collected from the 2 ha winter wheat field by means of 45 (7 cm diam.) pitfall traps in less than 3 months, whereby this high number is providing additional evidence for previous work reported in the literature of winter wheat field colonization by large numbers of spiders. The capacity of soil surface spiders to build up these high numbers, potentially consuming field crop insect pests at elevated rates suggests that they may play a significant role as natural control agents. The effectiveness of these spiders as natural enemies may be limited only by their apparently low feeding frequency reflecting a low rate of metabolism.

1992  Impact of the striped lynx spider (Araneae, Oxyopidae) and other natural enemies on the cotton fleahopper (Hemiptera, Miridae) in Texas cotton — Nyffeler M, Sterling WL & Dean DA — Environmental Entomology 21: 1178–1188
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Natural predation on nymphs and adults of the cotton fleahopper, Pseudatomoscelis seriatus (Reuter), was assessed during 108 h of visual observation in an insecticide-free cotton field in central Texas. Predaceous arthropods of 13 species (from nine families) were observed to forage on the fleahopper. More than 80% of the predation events observed were attributable to spiders. The striped lynx spider, Oxyopes salticus Hentz, was dominant among the predators observed eating fleahoppers (15 records of feeding in action). Cotton fleahoppers composed almost-equal-to 25% of the total prey of O. salticus during June and july. It was estimated during midseason that once every 4 d, one O. salticus would kill one cotton fleahopper. The assessment of the killing power of O. salticus, based on the predation rate and the predator-to-prey ratio (i.e., number of O. salticus individuals per fleahopper), suggests that these spiders are important mortality agents of the cotton fleahopper (greater-than-or-equal-to 15% prey mortality per day in the middle of the growing season). Additional fleahopper mortality is attributable to other predaceous arthropods such as Peucetia viridans (Hentz) (Oxyopidae), jumping spiders (Salticidae), crab spiders (Thomisidae), web-building spiders (Araneidae, Dictynidae, Theridiidae), damsel bugs (Nabidae), and ants (Formicidae).

Keywords: Pseudatomoscelis - Oxgopes - cotton

1992  Spiders associated with lemon horsemint (Monarda citriodora Cervantes) in east central Texas — Nyffeler M, Dean DA & Sterling WL — Texas Agricultural Experiment Station Bulletin (College Station/USA) B-1707: 1–6
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(© Texas Agricultural Experiment Station, The Texas A&M University System, College Station, Texas)

Spider predators were studied on flowering lemon horsemint, Monarda citriodora Cervantes, Lamiaceae, at two Texas locations to assess their potential as agroecosystem colonizers and natural control agents of insect pests. Oxyopes salticus Hentz, Peucetia viridans (Hentz), Misumenops celer (Hentz), and Metaphidippus galathea (Walckenaer) were predominant and are known (1) to disperse via air currents (ballooning), (2) to colonize cotton fields, and (3) to forage on cotton insect pests. About 90% of the spider individuals found on horsemint plants represent species known to attack and kill cotton fleahoppers, Pseudatomoscelis seriatus (Reuter), a key pest of cotton.

Keywords: horsemint - wild plants - spiders - predators - cotton fleahopper - Texas

1991  Impact of predation upon honey-bees (Hymenoptera, Apidae), by orb-weaving spiders (Araneae, Araneidae and Tetragnathidae) in grassland ecosystems — Nyffeler M & Breene RG — Journal of Applied Entomology 111: 179–189

Estimates of predation on the honey bee, Apis mellifera L., by a guild of orb-weaving spiders were made in two different habitats in central Europe. In the first habitat, an abandoned grassland (megaphorbe meadow), honey bees comprised 1 % (by numbers) of the 7480 prey items collected from orb-webs between May and September. Approximately 99 % of the 72 observed cases of predation on honey bees took place in the second half of summer (August-September), when the three large orb-weaver species Argiope bruennichi (Scopoli), Araneus quadratus Clerck and Araneus diadematus Clerck reached full size (matured) and built large, strong (ca. 25 cm diameter) webs. Predation by these spider species on honey bees in the first half of summer was apparently insignificant (only 1 % of observed predation events), probably due to their relatively small web and body size. Based on sampling counts of the number of webs per m² and the number of bees intercepted per web, we estimated that the spiders' prey kill per m² in the grassland averaged 1 honey bee every 4th day in August, and 1 every 5th day in September during rain free periods. About 95 % of observed orb-weaver predation was attributable to A. bruennichi and A. quadratus, while 5% was due to A. diadematus. The second estimate was made in another abandoned grassland habitat, heavily infested with the thistle Cirsium arvense (L.), in the same geographic area. Honey bees comprised 15 % (by numbers) of 215 prey items collected from webs of the dominant orb-weaver species (A. bruennichi) during August-September. We estimated that the A. bruennichi population may have killed approximately 1 honey bee per m² every 5th day in August during rain free periods. The economic status of orb-weaving spiders as predators is discussed, and we conclude that despite their activities in killing beneficial arthropods, these spiders should not be addressed as pests. Should bee keepers feel their hives are threatened, relatively innocuous cultural methods can be used in place of hazardous chemicals in the neighborhood of the hive that destroy the orb-weavers' web-sites in the grassland (moving).

1990  Efficacy of spider and ant predators on the cotton fleahopper [Hemiptera, Miridae] — Breene RG, Sterling WL & Nyffeler M — Entomophaga 35: 393–401

The efficacy of predators of immature cotton fleahoppers, Pseudatomoscelis seriatus (Reuter), was calculated using field and laboratory cage confinement tests for consumption rate. The predators tested were the striped lynx spider, Oxyopes salticus Hentz; the black and white jumping spider, Phidippus audax (Hentz); the celer crab spider, Misumenops celer Hentz; and the red imported fire ant, Solenopsis invicta Buren. The spider predators were evaluated in a cotton field using predator-prey confinement cages on cotton plants. Average percent control (sensu Abbott, 1925) of fleahoppers by O. salticus, P. audax, and M. celer were 42 %, 66 % and 32 % respectively. The rate of fleahopper consumption by red imported fire ants was measured in the laboratory using various numbers of ants and fleahoppers. Daily percent control by ants ranged from 0.5 % (single ant and fleahopper) to 100 % (colony linked). The functional response of the 4 arthropod species to different prey numbers is illustrated and discussed as is the relative potential usefulness of natural enemies to suppress fleahoppers on cotton.

Keywords: Pseudatomoscelis seriatus - predation - Miridae - cotton - natural control

1990  Evidence of low daily food-consumption by wolf spiders in meadowland and comparison with other cursorial hunters — Nyffeler M & Breene RG — Journal of Applied Entomology 110: 73–81

The feeding frequency of wolf spiders (Lycosidae, Pardosa spp., diurnal cursorial hunters), was assessed in a hay meadow in Central Europe. The wolf spiders' diet was composed primarily of small, soft-bodied insects of the taxa Collembola, Aphidoidea, and Diptera. Low feeding frequencies of wolf spiders were observed during both years (5.3% spiders feeding, and 3.9% spiders feeding). The percentage of feeding spiders did not differ statistically significantly over the two year period (overall, 4.9% of 710). Wolf spiders were observed masticating their prey into a "meat ball", a behavioral mechanism that may compensate for low feeding frequency by maximizing food assimilation. When the time available for killing and eating prey (foraging time (= 10 hrs/d); handling time (= 0.8 hrs/prey)), and the low field feeding frequencies are considered, it suggests low daily consumption rates for these spiders in the field compared to published laboratory studies.

1990  Spiders as predators of arthropod eggs — Nyffeler M, Breene RG, Dean DA & Sterling WL — Journal of Applied Entomology 109: 490–501

Examples of spiders preying upon the eggs of Araneae and Insecta are given from descriptions found in the literature from different regions of the world. In many cases, spiderlings or female spiders were feeding on the eggs of conspecifics (cannibalism). Evidence of conspecific predation on eggs has been reported for the families Dipluridae, Uloboridae, Scytodidae, Loxoscelidae, Pholcidae, Theridiidae, Agelenidae, Lycosidae, Gnaphosidae, Clubionidae, Thomisidae and Salticidae. Spiders feeding on the eggs of other species (interspecific predation by Salticidae upon eggs of other Salticidae and Uloboridae; Theridiidae upon the eggs of orb-weaving spiders) has also been noted. Evidence of spiders as predators of insect eggs is reported from North and South America, and Australia, largely in agroecosystems and forest ecosystems. In most cases, the spiders were observed feeding on the eggs of Lepidoptera (families Noctuidae, Tortricidae, Lymantriidae, Pyralidae and Sphingidae), and to a lesser extent, on coleopteran eggs (family Curculionidae).

1990  Spiders associated with selected European hay meadows, and the effects of habitat disturbance, with the predation ecology of the crab spiders, Xysticus spp (Araneae, Thomisidae) — Nyffeler M & Breene RG — Journal of Applied Entomology 110: 149–159

In hay meadows near Zurich, central Europe, the faunistic composition of the foliage-dwelling spiders was evaluated using sweep-net technique. Eleven families were represented from the 1502 spider individuals captured, the majority of which (> 85%) belonged to the families Theridiidae, Linyphiidae, Araneidae, Tetragnathidae, Lycosidae, Thomisidae and Salticidae. A low feeding frequency was observed in the field for the Xysticus spp. (< 10% with prey, N = 395), and a wide variety of arthropod taxa was consumed by the crab spiders including eight orders of insects, other spider species and a representative from a family of earthworms. The impact of mowing on spider densities in a diverse variety of meadows may range from mild to massive, however, emigration by spiders after their habitat has been disturbed, may serve as a beneficial arthropod generator, providing for the colonization of surrounding field crops.

1990  Facultative monophagy in the jumping spider Plexippus paykulli (Audouin) (Araneae: Salticidae) — Nyffeler M, Breene RG & Dean DA — Peckhamia 2: 92–96
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Predation by the jumping spider, Plexippus paykulli (Audouin), was recorded in a synanthropic habitat in Texas. Prey ranged in size from 3.4 to 19mm (x̅ ± SE = 6.79 ± 0.96mm) and consisted almost entirely of the German cockroach, Blatella germanica (L.) (96%, N=28). When compared to 9 other species of cursorial hunting spiders using Levins'niche breadth formula, the value for P. paykulli was 3 times lower than the value for the species with the narrowest prey diversity, to 53 times lower than the species with the broadest, indicating a trend toward monophagy. However, P. paykulli is known as a highly polyphagous predator with a broad feeding niche and the low dietary diversity observed is probably facultative monophagy, a feeding strategy invoked by a plethora of a single prey species accompanied by scarcity of alternative prey within the habitat. The ability of jumping spiders to narrow down their feeding niche during periods of an abundance of a single prey species and simultaneous rarity of other prey is significant from the standpoint of natural control, both in urban and agricultural settings.

1989  Foraging ecology and predatory importance of a guild of orb-weaving spiders in a grassland habitat — Nyffeler M & Benz G — Journal of Applied Entomology 107: 166–184

In an abandoned grassland ecosystem (megaforb meadow: Valeriano-Filipenduletum, Carex acutiformis Ehrh. type) in Eastern Switzerland, orb-weaving spiders dominated the spider community of the field layer (ca 60% of the yearly total of spiders in sweep samples). The orb-weavers of this grassland comprised predominantly the six species Argiope bruennichi (Scop.), Araneus quadratus Clerck, Araneus diadematus Clerck, Nuctenea cornuta (Clerck), Meta segmentata Clerck, and Tetragnathe extensa (L.), which combined formed a guild of insectivorous predators. The orb-weaving spiders in that grassland captured a variety of insect taxa (generalist predators); their major prey were Diptera (diverse species) and Homoptera (primarily leafhopper Stenocranus major (Kbm.) and aphids of the Anoecia corni group).

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1989  Prey selection and predatory importance of orb-weaving spiders (Araneae, Araneidae, Uloboridae) in Texas cotton — Nyffeler M, Dean DA & Sterling WL — Environmental Entomology 18: 373–380
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In an unsprayed cotton field in east Texas, orb weavers were one of the numerically dominant groups of spiders, constituting 10% of all spiders collected by D-vac during the summer of 1985 (range, 0.04 individuals/m² in June to 0.72 individuals/m² in August). Direct counts, conducted during peak orb-weaver density in August, showed that 0.86 individuals/m² were found. Their prey consisted of insects (> 99%) and spiders (< 1%). Aphids, which occasionally reach pest status in Texas cotton, were the most abundant prey of all five spiders (34.6-90%). Other important prey included small dipterans, cicadellids, and hymenopterans. Differences among the five spider species indicate that prey selection was occurring; this seems to be determined by web location, web inclination, and web strength.

Keywords: Arachnida - orb-weaving spiders - cotton - predation

1989  Natural control of the cotton fleahopper, Pseudatomoscelis seriatus (Reuter) (Hemiptera, Miridae), in Texas — Breene RG, Hartstack AW, Sterling WL & Nyffeler M — Journal of Applied Entomology 108: 298–305

The population dynamics of the cotton fleahopper, Pseudatomoscelis seriatus (Reuter), on cotton was predicted using the Texas Cotton Insect Model (TEXCIM) and compared with observed field data from east Texas. The presence of natural enemies and their estimated rate and efficacy of fleahopper consumption were used to calibrate the model to east Texas conditions. A correcting equation was incorporated into the model to account for fleahopper mortality due to rain. Current economic thresholds for cotton fleahoppers were used to determine the frequency of correct decisions made by the model. TEXCIM was free of type I and type II errors in 93% of 71 sampling periods compared with a previous rate of 86% in 57 sampling dates in an earlier version of TEXCIM. Cotton producers may now use either traditional chemical control or monitoring and conserving natural enemies to maximize profits.

1988  Feeding ecology and predatory importance of wolf spiders (Pardosa spp) (Araneae, Lycosidae) in winter-wheat fields — Nyffeler M & Benz G — Journal of Applied Entomology 106: 123–134

Predation by wolf spiders (Pardosa spp.) was studied for two years in two winter wheat fields in eastern Switzerland, one field being investigated each year. The following wolf spiders predominated in the investigated wheat fields: Pardosa agrestis (Westr.), Pardosa amentata (Clerck), and Pardosa palustris (L.). P. agrestis constituted greater than or equal to 75% of all Pardosa spp. observed in the field. Diptera, Collembola, and aphids constituted the major components in the spiders' diet (combined ca. 80% of the identified prey by numbers).

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1988  Natural enemies of spiders - mud dauber wasps in east Texas (Hymenoptera, Sphecidae) — Dean DA, Nyffeler M & Sterling WL — Southwestern Entomologist 13: 283–290
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(© The Society of Southwestern Entomologists)

Spider prey analysis of sphecid wasps was conducted in an east Texas farmland area. Two spider families, Araneidae and Theridiidae, comprised > 90% of the wasps' diet. The most abundant prey of these wasps were the orb-weavers, Gea heptagon (Hentz) (57.1% of total), and Acanthepeira stellata (Walckenaer) (17.7%). The southern black widow, Latrodectus mactans (F.) (5.9%), was also an important component of the diet of these wasps. Remaining families represented < 10%

1988  Prey analysis of the spider Achaearanea riparia (Blackw) (Araneae, Theridiidae), a generalist predator in winter-wheat fields — Nyffeler M & Benz G — Journal of Applied Entomology 106: 425–431

In winter wheat fields of eastern Switzerland, the foraging of the comb-footed spider Achaearanea riparia (Blackw.) was studied. This spider - occurring in the winter wheat ecosystem in estimated numbers of ca. 0.6 ind./m² - was observed to be a generalist predator of small to medium-sized arthropods. With its irregular webs - which A. riparia spins in the lowest 15% of the foliage - this spider captured a variety of arthropods, primarily of the orders Hymenoptera (36% by numbers, mostly apterous ants), Coleoptera (19%, mostly Staphylinidae, and Carabidae of the genus Amara), Homoptera (14%, mostly aphids), Diptera (6%), and Araneae and Acari (6%, Micryphantidae and Oribatidae).

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1988  Prey and predatory importance of micryphantid spiders in winter-wheat fields and hay meadows — Nyffeler M & Benz G — Journal of Applied Entomology 105: 190–197

Micryphantidae (Erigone spp. and Oedothorax spp.) dominate the spider faunas on the ground surface of winter wheat fields and hay meadows (> 75 % of the numbers of spiders sampled with pitfall traps during the summer). These small spiders of <3 mm adult body length, which capture prey with tiny irregular webs spun over small depressions on the ground, were observed to be generalist predators of small soft-bodied arthropods of the classes Insecta and Arachnida. Collembola (> 35 % by numbers) and aphids (> 25 %) were the prey most frequently captured by micryphantid spiders. Larger and hard-bodied arthropods such as carabid and staphylinid beetles were missing in these spiders' prey spectrum. Micryphantidae were observed to be predaceous on the agriculturally harmful cereal aphids Rhopalosiphum padi L. and Sitobion avenae F.

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1988  Prey records of the web-building spiders Dictyna segregata (Dictynidae), Theridion australe (Theridiidae), Tidarren haemorrhoidale (Theridiidae), and Frontinella pyramitela (Linyphiidae) in a cotton agroecosystem — Nyffeler M, Dean DA & Sterling WL — Southwestern Naturalist 33: 215–218
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Diets of the four small-sized web-building spiders Dictyna segregata Gertsch and Mulaik, Theridion australe Banks, Tidarren haemorrhoidale (Bertkau), and Frontinella pyramitela (Walckenaer) were studied in an unsprayed cotton agroecosystem in eastern Texas by analyzing prey found in these spiders' webs. Aphids were the most dominant food category in the potential prey complex (D-Vac samples) as well as in the actual prey (insects found in webs) of the four spider species. Since these spiders captured mainly small insects with a size of <3mm, they can be considered to be potential predators of the cotton fleahopper.

1988  The southern black-widow spider, Latrodectus mactans (Araneae, Theridiidae), as a predator of the red imported fire ant, Solenopsis invicta (Hymenoptera, Formicidae), in Texas cotton fields — Nyffeler M, Dean DA & Sterling WL — Journal of Applied Entomology 106: 52–57

In cotton fields of east Texas, the southern black widow spider, Latrodectus mactans (F.), was observed to capture the red imported fire ant, Solenopsis invicta Buren, which constituted 75 % of the prey of L. mactans. Remains of workers, queens, and males of S. invicta were found in the spider webs. L. mactans were observed to feed on ants captured in the webs indicating that S. invicta were used as a food source. Juveniles as young as third instar were observed capturing S. invicta workers. ln the same area, 16 other species of spiders were observed to be predators of S. invicta.

1988  Spiders inhabiting the field layer of a dry meadow near Zurich, Switzerland — Nyffeler M & Benz G — Mitteilungen der Schweizerischen Entomologischen Gesellschaft 61: 21–28
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In a dry grassland (Bromus meadow) located in the protected "Katzensee" area (eastern Switzerland) the composition of foliage-dwelling spiders was studied by taking sweep net samples during one summer season. The total number of immature plus adult spiders per 100 single sweeps increased (quadrupled) from June to August (egg-laying of many adults in spring followed by hatching of the spiderlings in summer). A yearly total of 234 adult specimens - composing > 2/3 females and representing 21 identified species - was collected by sweeping (based on more than 3000 single sweeps). Immature stages (overall, 82%) outnumbered the adult spiders in the sweep net samples. Thirteen spider families were found in the dry meadow. The seven families Thomisidae, Salticidae, Micryphantidae, Tetragnathidae, Pisauridae, Theridiidae, and Araneidae prevailed in the yearly total of collected spiders (combined 89% of the 1295 immature plus adult specimens, 96% of the adults). Six species - Enoplognatha ovata (Clerck), Evarcha arcuata (Clerck), Heliophanus flavipes (Hahn), Hylyphantes nigritas (Simon), Tetragnatha pinicola L. Koch, and Xysticus cristatus (Clerck) - combined made up > 80% of all collected adult spiders. The non-webbuilding spiders E. arcuata and X. cristatus considered to be insectivorous generalist predators were the two most frequently collected species. The results are compared with data of the foliage-dwelling spider community of another grassland habitat located in the same geographic area.

1987  Evaluation of the importance of the striped lynx spider, Oxyopes salticus (Araneae, Oxyopidae), as a predator in Texas cotton — Nyffeler M, Dean DA & Sterling WL — Environmental Entomology 16: 1114–1123
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Predation by the striped lynx spider, Oxypes salticus, Hentz, on cotton arthropods was studied in an unsprayed field in east Texas. O. salticus was the most abundant spider species in cotton (68% of all spiders collected by D-Vac), with population densities of <0.1 spiders per m² in June gradually increasing to 7.2 per m² in September. This diurnally and nocturnally feeding spider captured prey ranging between 0.1 and 1.1 of its own size. Most prey were small (average body length = 2.61 ± 0.16 mm [SEM]). The natural diet of O. salticus, a generalist predator, was diverse, and consisted (by number) mainly of Solenopsis invicta Buren (21.9%), leafhoppers (17.2%), dipterans (15.6%), aphids (14.1%), and spiders (14.1%). Predaceous arthropods, including Geocoris bugs, and larvae of Chrysopa and Syrphidae, composed 42% of the spiders' diet. The proportion of O. salticus feeding at any one time was <5% throughout the 1985 season. A subadult/adult spider captured about one prey daily in the middle of the growing season. Based on population density counts and the assessment of the prey capture rate we estimated that in the middle of the growing season ca. 0.12 million prey may have been killed by O. salticus per ha cotton land per week (weekly kill ca. 4.5% of the average arthropod density).

Keywords: Oxyopes salticus - cotton - prey capture rate - prey preference - phenology

1987  Feeding ecology of the orb-weaving spider Argiope aurantia [Araneae, Araneidae] in a cotton agroecosystem — Nyffeler M, Dean DA & Sterling WL — Entomophaga 32: 367–375

Twenty females of the orb-weaving spider Argiope aurantia Lucas were introduced into a cotton field in east Texas in order to study the feeding ecology of this spider. In the 24 h after the release of these spiders in the cotton field, one had moved over a distance of 53 m. The released spiders spun webs with an average diameter of 33.5 cm with the hub an average of 39 cm above the ground. The diet of A. aurantia was diverse which characterizes this species as a food generalist. Major food components were aphids (30 %), Diptera (26.8 %), grasshoppers (17.9 %), and Hymenoptera (12.6 %). The spiders' prey length ranged from 0.4 to 47 mm (mean = 7.7 ± 0.83 mm). Adult females of A. aurantia have the potential to kill prey of up to ca. 200 % of their own size. However, two-thirds of the prey items had a length of < 3 mm, while only 25 % of the prey items had a length of ≥ 20 mm. A. aurantia was found to be a predator of the cotton fleahopper (about 1 % of the spiders' diet), which is a key pest of cotton.

Keywords: Spiders - cotton - Argiope - orb-weavers - prey size

1987  Foraging by selected spider predators on the cotton fleahopper (Hemiptera, Miridae) and other prey — Dean DA, Sterling WL, Nyffeler M & Breene RG — Southwestern Entomologist 12: 263–270
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(© The Society of Southwestern Entomologists)

Observed predation by the hunting spiders Phidippus audax (Hentz), Metaphidippus galathea (Walckenaer), and Misunenops celer (Hentz) on the cotton fleahopper, Pseudatomoscelis seriatus (Reuter), inhabiting cotton and woolly croton plants in east Texas is described. Fifty percent or more of the prey items in woolly croton consisted of the cotton fleahopper, an important pest of cotton in Texas and neighboring states. Twenty-two spider species which are known to prey on this insect are listed. Prey records of these three spiders plus Pardosa pauxilla Montgomery on other arthropods are included. Less than 10% of the spiders were observed feeding. Predaceous arthropods, non-pest and pest insects were found in the diet of these spiders.

1987  Predation by green lynx spider, Peucetia viridans (Araneae, Oxyopidae), inhabiting cotton and woolly croton plants in east Texas — Nyffeler M, Dean DA & Sterling WL — Environmental Entomology 16: 355–359
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Predation by green lynx spider, Peucetia viridans (Hentz), was studied on cotton and woolly croton plants in East Texas. This species feeds both diurnally and nocturnally. P. viridans was observed feeding on insects of orders Diptera, Hymenoptera, Heteroptera, Homoptera, Coleoptera, Lepidoptera, Neuroptera, and Odonata, as well as on several spider species. Predaceous arthropods (e.g., Hippodarnia conuergens Guérin-Méneville, Coccinellidae; Chrysoperla rufiIabris [Burmeister], Chrysopidae) constituted more than half of the spiders' diet. In cotton, P. viridans was found to be a predator of the pests Heliothis zea (Boddie) and Alabama argillacea (Hübner) (together 8% of the spiders' prey). Size of killed prey in cotton ranged between 0.14- and 1.3-fold the spiders' size (average prey length, 5.90 ± 0.99 mm). On woolly croton plants, P. viridans was often seen feeding on cotton fleahopper, Pseudatomoscelis seriatus (Reuter) (numerically almost 30% of the spiders' prey), which is a key pest in cotton. It was estimated that on cotton and croton plants in East Texas, one P. viridans captured an average of less than one prey daily. Our results are compared with data in the literature on the diet of P. viridans.

Keywords: Peucetia - Pseudatomoscelis - cotton - croton - predation - diet

1987  Spiders in natural pest-control - a review — Nyffeler M & Benz G — Journal of Applied Entomology 103: 321–339   doi> 10.1111/j.1439-0418.1987.tb00992.x 

In spite of the large number of studies about the ecology of spiders carried out in the last two decades in different types of ecosystems all over the world, the significance of these animals as natural control agents is still largely unknown. In this paper the literature about that subject is reviewed. Totally 300 scientific papers, published between 1920 and 1984, are cited here. Several European and American studies have provided evidence, that in undisturbed grassland ecosystems and forest ecosystems spiders can play an important ecological role as predators of insects and other invertebrates. Also in orchards, not treated with pesticides, that are to a certain degree comparable with forest ecosystems, spiders can be abundant predators.

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1987  The foliage-dwelling spider community of an abandoned grassland ecosystem in eastern Switzerland assessed by sweep sampling — Nyffeler M & Benz G — Mitteilungen der Schweizerischen Entomologischen Gesellschaft 60: 383–389
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(© Schweizerische Entomologische Gesellschaft)

The foliage-dwelling spiders of an abandoned grassland ecosystem (Valeriano-Filipenduletum, Carex acutiformis Ehrh. type) in eastern Switzerland were studied from June to September by the sweeping technique. A total of 632 adult specimens representing 22 identified species had been collected by sweeping (based on totally ca. 2000 single sweeps). More than two thirds of the sampled adult spiders were females. At all times, more immature than adult spiders were captured (overall, 83% immatures). Among the 3756 collected spiders (immatures plus adults), the six families Agelenidae, Araneidae, Micryphantidae, Pisauridae, Salticidae, and Tetragnathidae prevailed in the sweep net samples (combined ca. 90% of all spiders). The five species Evarcha arcuata (Clerck), Hylyphantes nigritus (Simon), Neottiura bimaculata (L.), Pisaura mirabilis (Clerck), and Tetragnatha extensa (L.) constituted combined > 80% of all adult spiders sampled by sweeping. The web-building spiders T. extensa and H. nigritus were the two species most frequently captured. Adults of large orb-weaving spiders (Argiope bruennichi [Scopoli], Araneus quadratus Clerck, and Araneus diadematus Clerck) were abundant in the investigated grassland habitat (assessed by web counts), but obviously underproportionately represented in the sweep net samples. Considering the total number of spiders (immatures plus adults) per 100 single sweeps, a strong increase from spring to late summer was noticed which is considered to be primarily due to egg-laying of the most dominant species in spring followed by hatching of the spiderlings in the course of the summer. Since spiders are abundant predators in this grassland ecosystem (ca. 0.1 m² web area/m² ground area, alone due to orb-weavers in August/Sept.), they may be important mortality agents of grassland arthropods.

1986  Evidence for displacement of a North-American spider, Steatoda borealis (Hentz), by the European species S. bipunctata (Linnaeus) (Araneae, Theridiidae) — Nyffeler M, Dondale CD & Redner JH — Canadian Journal of Zoology 64: 867–874
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(© 2006 NRC Research Press Canada)

The European spider Steatoda bipunctata has apparently been introduced into North America through human transport. The earliest American collections were made in Nova Scotia in 1913. Until about 1933, specimens were known only on the coast of the Atlantic provinces, Maine, and along the St. Lawrence River and Lake Ontario, but they are now found widely in the Atlantic Provinces, northernmost New England, and southern Québec and Ontario. Habitats include buildings, bridges, piles of lumber and firewood, and crevices on tree trunks or among rocks. Evidence indicates that S. bipunctata, which closely resembles the native S. borealis in size, colour, microhabitat, diel activity, prey selection and utilization, life history, and sexual behaviour, can displace S. borealis. Displacement is, however, only partial, as S. borealis persists in forest habitats, where human influence is minimal. Laboratory tests on reproductive potential and interspecific aggression failed to demonstrate the method by which displacement takes place.

1986  Feeding habits of the spiders Cyclosa turbinata (Walckenaer) and Lycosa rabida Walckenaer — Nyffeler M, Dean DA & Sterling WL — Southwestern Entomologist 11: 195–201
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Prey records of the orb-weaving spider Cyclosa turbinata (Walckenaer) and the wolf spider Lycosa rabida Walckenaer in an east Texas agroecosysten are presented. Aphids were numerically the most dominant component in the potential prey (based on D-Vac samples) as well as in the actual prey found in webs of C. turbinata. L. rabida was studied during the night using the head-light method (gleaming eyes) and ca. 4% of those collected where feeding. It is estimated that L. rabida captured less than one prey per spider daily.

1986  Acoustic communication in two spider species of the genus Steatoda (Araneae: Theridiidae) — Lee RCP, Nyffeler M, Krelina E & Pennycook BW — Mitteilungen der Schweizerischen Entomologischen Gesellschaft 59: 337–348
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(© Schweizerische Entomologische Gesellschaft)

Steatoda bipunctata and S. borealis are two closely related species of spiders, which were entirely allopatric until approximately one hundred years ago, when S. bipunctata, was introduced into the range of S. borealis, where it has since spread. Reproductive isolation between the two species apparently results from mechanical incompatibility of their copulatory organs. In this report, the stridulatory organs of the males are described, and the sounds produced by males during sexual and agonistic behaviour are analysed. The interspecific differences in the sounds are small compared with the range of variation within the species. The stridulatory organs are extremely similar in the two species. There is no evidence that differences in male sounds could be used as a cue for species recognition. This is in contrast with species which have co-existed for longer periods, and which apparently use species specific sounds as recognition mechanisms.

1984  Eine borkenkäferfressende Spinne, Troxochrus nasutus SCHENKEL (Araneae, Erigonidae) — Moor H & Nyffeler M — Faunistisch-Ökologische Mitteilungen 5: 193–197

In a spruce forest near Aarau (Switzerland) a small erigonid spider, Troxochrus nasutus Schenkel, was observed feeding on Hylurgops palliatus Gyll. and Pityogenes chalcographus L. bark beetles.

1983  Ostearius melanopygius (O. P.-Cambridge) (Aran., Micryphantidae) new to Switzerland. On a mass occurrence of the spider in Zurich and the destruction of its population by snow [in German] — Benz G, Nyffeler M & Hug R — Mitteilungen der Schweizerischen Entomologischen Gesellschaft 56: 201–204
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(© Schweizerische Entomologische Gesellschaft)

Ostearius melanopygius (O.P.-CAMBRIDGE) (Aran., Micryphantidae) new for Switzerland. On a mass occurence of the spider in Zurich and the destruction of its population by snow. - The first record of O. melanopygius to the fauna of Switzerland is given and its mass occurrence on the compost heaps of the compost preparing facility of the city of Zurich as well as the destruction of the spider population by snowfall is described.

1983  Eine Notiz über borkenkäfertötende Spinnen — Moor H & Nyffeler M — Mitteilungen der Schweizerischen Entomologischen Gesellschaft 56: 195–199
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A note on spiders killing bark beetles - In a spruce forest near Aarau (Switzerland) web-building spiders were observed to be predators of Hylurgops palliatus Gyll. and Pityogenes chalcographus L. bark beetles.

1983  Eine Notiz zur ökologischen Bedeutung der Radnetzspinnen als Blattlausprädatoren in Gärten — Nyffeler M — Mitteilungen der Schweizerischen Entomologischen Gesellschaft 56: 200–
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A note on the ecological role of orb-weaving spiders as predators of aphids in gardens - Field studies in gardens in Zurich (Switzerland) have shown that aphids are an essential component in the prey of orb-weaving spiders (family Araneidae). Garden-dwelling orb-weavers were observed as predators of the agricultural harmful aphids Myzus cerasi F., Myzus lythri Schrk., Rhopalosiphum padi L., Brachycaudus cardui L., and Brevicoryne brassicae L.

1982  Eine Notiz zum Beutefangverhalten der Radnetzspinne Argiope bruennichi (Scopoli) (Araneae, Araneidae) [A note on the predatory behavior of the orb-weaving spider Argiope bruennichi (Scopoli)] — Nyffeler M & Benz G — Revue Suisse de Zoologie 89: 23–25
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A field study near Zurich (Switzerland) has shown that the orb-weaving spider Argiope bruennichi (Scopoli) has a predatory behaviour towards Lepidoptera which is similar to that of Argiope-species in other continents. Instead of the normal sequence: wrapping up of prey → bite, lepidopterous insects are first bitten and then wrapped up.

1982  Spinnen als Prädatoren von landwirtschaftlich schädlichen Blattläusen [Spiders as predators of agricultural harmful aphids] — Nyffeler M & Benz G — Anzeiger für Schädlingskunde, Pflanzenschutz und Umweltschutz 55: 120–121

Direct observations in grasslands and cereal fields near Zurich (Switzerland) have shown that aphids constitute an essential component in many spiders' prey. Spiders were observed to be predators of the agricultural harmful aphids Rhopalosiphum padi L., Sitobion avenae F., Metopolophium dirbodum Walck., Hyalopterus pruni Geoffr., Myzus persicae Sulz. and Aphis fabae Scop.

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1982  Die ökologische Bedeutung der Spinnen in Forst-Ökosystemen, eine Literaturzusammenstellung [The ecological importance of spiders in forest ecosystems, a literature-review] — Nyffeler M — Anzeiger für Schädlingskunde, Pflanzenschutz und Umweltschutz 55: 134–137

The most important literature on the ecological importance of spiders for forest ecosystems was compiled and analyzed. Forest spiders normally live in densities of 50 to 200 individuals/m² and prey, at least in Europe, predominantly on small soft-bodied insects (Diptera and Collembola mainly). However, bigger insects, including various forest pests, are also found in their prey. According to the present stand of knowledge the spiders of the soil surface seem to be important insect predators, whereas the ecological importance of spiders living on the trees is still controversial.

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1982  Bemerkenswerte Spinnenfunde in Wiesen und Getreidefeldern bei Zürich — Nyffeler M & Benz G — Mitteilungen der Schweizerischen Entomologischen Gesellschaft 55: 97–100
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Remarkable spider findings in meadows and cereal fields near Zurich - From 1976 to 1981 arachnological studies were carried out in the region of Zurich (Switzerland). Findings of Oedothorax fuscus (Blackw.), Porrhomma oblitum (O.P.-Cambr.), Dictyna puella Simon, Theridion boesenbergi Strand, Xysticus lineatus (Westring), Xysticus kempeleni Thorell, and Myrmarachne formicaria (Deg.) in meadows, as well as of Oedothorax tuberosus (Blackw.), O. fuscus, Araneus alsine Walck. and Argiope bruennichi (Scop.) in cereal fields are described. The findings were compared with data from the literature.

1982  Field studies on the ecological role of the spiders as insect predators in agroecosystems (abandoned grassland, meadows, and cereal fields) — Nyffeler M — PhD Thesis, Swiss Federal Institute of Technology Zurich [Diss. ETH # 7097], 174 pp.
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From 1976-1979, the ecology of spiders was investigated in abandoned grasslands, cultivated meadows and cereal fields near Zurich (Switzerland). The spiders of such ecosystems live in two strata, (1) on the ground surface, (2) in the vegetation zone. Different spider communities are found in the two strata.
In abandoned grasslands, the spiders live undisturbed all year round. They can therefore build up relatively large populations in these biotopes (near Zurich about 10 spiders/m²; significantly higher values are reported in literature). Cultivated fields, on the other hand, are periodically mown, whereby the living space and the egg sacs of many spiders are destroyed. Only relatively small spider populations live therefore in the vegetation zone of cultivated fields (about 1 spider/m² in cultivated meadows and 0.1-0.6 spiders/m² in cereal fields). The ground surface of cultivated fields is rather densely populated (15-42 spiders/m² in cultivated meadows and 10-50 spiders/m² in cereal fields).
The spiders in the vegetation zone of cultivated meadows and cereal fields are primarily predators of Diptera and Homoptera. In the vegetation zone of abandoned grasslands, in addition honey bees and/or grasshoppers can form an essential part of the prey biomass of large web-building spiders. On the ground surface of cultivated meadows and cereal fields, the predominant spiders are mainly predators of small, soft-bodied insects (Collembola, Diptera, aphids etc.). From the food analyses it follows that the spiders are predators of pest insects (e.g. cereal aphids), indifferent species (most Diptera), and of beneficial arthropods as well (honey bees, Chrysopidae, Coccinellidae etc.).
The energy flow (prey killed) through the spider communities of the vegetation zone of abandoned grasslands can be high, e.g. >900 MJ/ha/year in a megaphorbe meadow. In comparison, the energy flow through the spider communities of cultivated fields is significantly lower, e.g. 1.1-6.5 MJ/ha/year in cereal fields, and <0.5 MJ/ha/year in maize fields. The energy flow through the ground-dwelling spider communities of cultivated fields should amount to about 10-50 MJ/ha/year.
Abandoned grasslands often are veritable spider paradises. In these ecosystems, the spiders of the vegetation zone represent an important predator group. In the vegetation zone of cereal fields, on the contrary, spiders do not seem to play a significant ecological role. Further studies will show, to what extent the ground-dwelling spiders in cultivated meadows and cereal fields are of ecological importance.

1982  Funde von Krabbenspinnen der Gattung Heriaeus Simon 1875 in zwei Feuchtgebieten bei Zürich (Araneae, Thomisidae) — Nyffeler M & Benz G — Mitteilungen der Schweizerischen Entomologischen Gesellschaft 55: 383–384
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Findings of crab spiders, genus Heriaeus, in wetlands near Zurich - Crab spiders of the genus Heriaeus have been found in a moorland-ecosystem-complex and in a megaphorbe meadow (Valeriano-FilipenduIetum) near Zurich (Switzerland).

1981  Freilanduntersuchungen zur Nahrungsökologie der Spinnen: Beobachtungen aus der Region Zürich [Field studies on the feeding ecology of spiders - observations in the region of Zurich (Switzerland)] — Nyffeler M & Benz G — Anzeiger für Schädlingskunde, Pflanzenschutz und Umweltschutz 54: 33–39

The results of studies on the feeding ecology of spiders from 1974-1980 can be summed up as follows: All species of spiders examined fed exclusively on evertebrates (Insecta, Arachnida, Isopoda, Myriapoda, Lumbricidae). In most cases, more than 90 % of the food consisted of insects.
Numerous spiders living in the vegetation stratum feed mainly on small flying insects, such as Diptera and aphids. The same is true for the dominant spiders living on the surface of the soil, though their prey spectrum is supplemented by Collembola and apterous aphids. Thus in the average prey spectrum of spiders small insects with a soft cuticle dominate. Exceptions are found with Argiope bruennichi, a predator of grasshoppers and bees, Agelena spp. feeding mainly on relatively large insects, Xysticus cristatus, which, when hunting on the ground, preys on ants and spiders, Achaearanea riparia, preying on ants and-beetles, Coelotes terrestris, a specialized predator of beetles, and Pholcus phalangioides, preying on wood-lice, spiders, opilionides etc. The prey spectra of the spider species examined vary considerably in breadth. So the food spectrum of the funnel-web spiders of the polyphagous genus Agelena is large compared to that of the oligophagous C. terrestris. Whereas in most spider species the size of their prey is relatively small or only reaches the size of the predator (size of prey ≤ size of predator), some species, mainly of Thomisidae and Theridiidae, prey at times upon prey larger than they are.
Spiders are secondary consumers belonging predominantly to herbivor food chains. Wolf spiders living on forest grounds intervene also in detritus food chains. Scorpionflies (genus Panorpa) often feed on prey animals in spider webs (food robbery).

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1981  Einige Beobachtungen über die Flucht von adulten Lepidopteren aus den Netzen orbiteler Spinnen [Some observations on the escape of adult lepidoptera from webs of orb-weaving spiders] — Nyffeler M & Benz G — Anzeiger für Schädlingskunde, Pflanzenschutz und Umweltschutz 54: 113–114

Field studies near Zurich (Switzerland) have shown, that adult Lepidoptera often are able to escape from spider webs of the families Argiopidae and Tetragnathidae. In the food of these orb-weaving spiders Lepidoptera made up only a very small part. The capability of the lepidopterans to escape from spider webs seems to be of great ecological importance.

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1981  Einige Beobachtungen zur Nahrungsökologie der Wolfspinne Pardosa lugubris (Walck.) [Some observations on the feeding ecology of the wolf-spider Pardosa lugubris (Walck.)] — Nyffeler M & Benz G — Deutsche Entomologische Zeitschrift 28: 297–300   doi> 10.1002/mmnd.19810280406 

In a beech spruce forest near Zurich (Switzerland) studies on the feeding ecology of the wolf spider Pardosa lugubris (Walck.) were carried out. Only 6% of 513 wolf spiders caught by hand held a prey (strongly deformed) between their chelicerae. The food of P. lugubris exclusively was composed of small, soft-bodied arthropods (Insecta, Arachnida). > 85 % of the identified prey animals consisted of Collembola (Genera Orchesella and Tomocerus) and small Diptera

1981  Dictyna puella Simon 1870, neu für die Schweiz (Araneae, Dictynidae) — Nyffeler M & Benz G — Mitteilungen der Schweizerischen Entomologischen Gesellschaft 54: 269–270
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Dictyna puella Simon 1870, new for Switzerland - In a cultivated meadow near Zurich (Switzerland) one male of the dictynid spider Dictyna puella was caught at the end of June 1979 with a sweep-net. This is the first record of this spider species for Switzerland.

1981  Ökologische Bedeutung der Spinnen als Insektenprädatoren in Wiesen und Getreidefeldern [The ecological role of the spiders as insect predators in meadows and cereal fields] — Nyffeler M & Benz G — Mitteilungen der Deutschen Gesellschaft für allgemeine und angewandte Entomologie 3: 33–35
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In the vegetation stratum of uncultivated meadows spiders represent a great potential of insectivorous predators. If uncultivated meadows are converted to cultivated land the predator potential of the vegetation is lost to a great part. Contrary to this the epigeous spiders reach relatively high densities also in cultivated land and may therefore stabilize certain insect populations of meadows and cereal fields.

1981  Juvenile Kreuzspinne als Nahrungsdieb im Netz einer adulten Kreuzspinne Araneus quadratus CL. — Nyffeler M — Mitteilungen der Entomologischen Gesellschaft Basel 31: 90–
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1980  Kleptoparasitismus von juvenilen Kreuzspinnen und Skorpionsfliegen in den Netzen adulter Spinnen [Juvenile orb-weaving spiders and scorpionflies as kleptoparasites of adult web-building spiders] — Nyffeler M & Benz G — Revue Suisse de Zoologie 87: 907–918
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(© Muséum d'histoire naturelle de Genève et la Société suisse de Zoologie)

Dead insects caught in spider webs attract diverse carnivorous arthropods (predators and saprophages). Especially juvenile stages of orb-weaving spiders (Nuctenea umbratica, N. cornuta, N. sclopetaria) as well as adult scorpionflies enter the webs of adult spiders and feed there on the dead insects. Since the intruders feed on the potential prey of the web-owners the relationship between the two must be classified as parasitism. However, these intraspecific and interspecific thefts of food are probably special forms of nutritional parasitism with transitions to commensalism. The question how the kleptoparasites avoid being killed by the host spiders has been discussed. Our observations are compared with other published reports and lead to the conclusion that all transitions from purely occasional thefts of food to permanent and compulsory kleptoparasitism exist.

1980  Ecology of spiders in meadows near Zurich (Switzerland) — Benz G & Nyffeler M — In: Proceedings of the 8th International Congress of Arachnology, Vienna (Gruber J, ed). Egermann, Wien: 121–125
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1980  The role of spiders as insect predators in cereal fields near Zurich (Switzerland) — Nyffeler M & Benz G — In: Proceedings of the 8th International Congress of Arachnology, Vienna (Gruber J, ed). Egermann, Wien: 127–131
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1979  Nischenüberlappung bezüglich der Raum und Nahrungskomponenten bei Krabbenspinnen (Araneae: Thomisidae) und Wolfspinnen (Araneae: Lycosidae) in Mähwiesen [Overlap of the niches concerning space and prey of crab spiders (Araneae, Thomisidae) and wolf spiders (Araneae, Lycosidae) in cultivated meadows] — Nyffeler M & Benz G — Revue Suisse de Zoologie 86: 855–865
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(© Muséum d'histoire naturelle de Genève et la Société suisse de Zoologie)

Crab spiders in unmown meadows (Xysticus spp., Misumena spp.) live in the vegetation stratum where they prey mainly on nectar sucking Diptera and Hymenoptera in the flowering zone. Wolf spiders of the genus Lycosa on the other hand hunt on the ground Collembola and aphids. On mowing the vegetation stratum is removed and the crab spiders move to the ground, i.e. the formerly separated spatial component of the niches of crab spiders and wolf spiders overlap. Their prey, however, does not overlap significantly, because the epigeic crab spiders are able to prey on bigger animals (ants, carabides, spiders, lumbricide worms etc.) than wolf spiders. When Xysticus spp. and Lycosa spp. meet, the Lycosa is usually killed by the Xysticus. One tenth of the prey of epigeic crab spiders consists of wolf spiders.

1979  Zur ökologischen Bedeutung der Spinnen der Vegetationsschicht von Getreide- und Rapsfeldern bei Zürich (Schweiz) [Studies on the ecological importance of spider populations for the vegetation of cereal and rape fields] — Nyffeler M & Benz G — Zeitschrift für Angewandte Entomologie 87: 348–376

Ecological investigations on spider populations of cereal and rape fields near Zurich (Switzerland) and their prey spectra in 1976/77 led to the conclusion that the population densities of spider populations of the vegetation strata were low (< 0.1-0.1 spiders/m² in corn fields, and 0.1-0.6 spiders/m² in other fields) and their impact on insect populations almost insignificant (100-1200 g insects/ha/year, mostly small diptera and aphids). Due to the destruction of the spider eggs at harvest at the end of July, the fields have to be repopulated from extensively or not cultivated small biotopes such as road sides and the margins of woods etc. every year. The yearly preying activity of the spiders of cereal and rape fields is thus restricted to 60-70 d between immigration and harvest, except for corn fields harvested later in the year. Numerically most dominant in the vegetation of cereal and rape fields were Theridium impressum, Tetragnatha extensa, Mangora acalypha, Araneus cucurbitinus, A. cornutus, and A. ceropegius

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1978  Die Beutespektren der Netzspinnen Argiope bruennichi (Scop.), Araneus quadratus Cl. und Agelena labyrinthica (Cl.) in Ödlandwiesen bei Zürich [Prey selection by web spiders Argiope bruennichi (Scop), Araneus quadratus Cl, and Agelena labyrinthica (Cl) on fallow land near Zurich, Switzerland] — Nyffeler M & Benz G — Revue Suisse de Zoologie 85: 747–757
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(© Muséum d'histoire naturelle de Genève et la Société suisse de Zoologie)

Prey analyses of the two orb web spiders Argiope bruennichi and Araneus quadratus, and of the funnel web spider Agelena labyrinthica have been made on fallow land near Zurich (Switzerland). A. bruennichi constructs its web near the ground, A. quadratus in the flowering top zone, and A. labyrinthica in all strata of the vegetation. The prey of the spiderlings of all three species consists mainly of small midges and aphids. On the basis of numbers of insects captured, small Diptera are the main prey of adult A. bruennichi as well as A. quadratus. In terms of biomass, however, honey bees dominate in the prey of A. quadratus, and honey bees and grasshoppers in the prey of A. bruennichi. The latter species has been known in Europe as an almost monophagous predator of grasshoppers. On fallow land near Zurich, however, we found it more often preying on honey bees than on grasshoppers. The range of prey of A. labyrinthica is much wider and consists of medium- and relatively large-sized insects, mainly Orthoptera, Coleoptera, Hymenoptera (honey bees and ants), Diptera, and Lepidoptera.