Testing traditional hypotheses about prey capture efficiency in orb-web spiders
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Testing traditional hypotheses about prey capture efficiency in orb‑web spiders Fernanda Carolina da Silva1 · Mateus Moleta2 · Camila Alves Dos Anjos2 · Gabriel Marra Schade2 · Gabriel Staichak2 · Leonardo Tozetto2 · Flayane Gonçalves2 · Kauane Martins2 · Isabela Farion2 · Clarisse Kuhn Krug2 · Diogo Andrade Costa3 · Leonardo Castilho4 · Eduardo Bessa4,5 Received: 25 March 2020 / Accepted: 10 July 2020 © Japan Ethological Society 2020
Abstract To capture prey, orb-web spiders create complex traps whose efficiency is contingent on a variety of factors that are not yet completely understood, including web size, competition for food, sun exposure, presence of web decorations and web orientation. Here we evaluate such factors in the field and ask which of them are the most influential variables affecting the quantity of prey captured in Argiope argentata webs. Webs were observed during the morning and the number of prey attached to each web was counted. Using the approach of information criteria based on the Akaike information criterion (AIC) values of each candidate model, we averaged the parameters of a global model, finding that the only predictor which 95% confidence interval did not include zero, was exposure to sunlight (whether the web is continuously shaded or continuously exposed to sunlight). All other variables did not explain variation in prey capture. We conclude that only sun exposure has an important effect on orb-web spiders’ prey capture efficiency in A. argentata. We additionally argue that silk decorations have different functions depending on the habitat and the species. Keywords Araneidae · Behavior · Tropical spiders · Argiope argentata · Foraging
Introduction Sit-and-wait predators do not search for food; instead, they wait until prey items come close before attacking them. Given that sit-and-wait predators cannot actively search for high quality prey, an important ecological strategy is selecting the appropriate place to ‘sit’ (Hanna and Eason 2013). And in the case of predators that build traps (e.g. spider
* Leonardo Castilho [email protected] 1
Ecology Graduation Program, Universidade Federal de Santa Catarina. Florianópolis, Santa Catarina, Brazil
2
Universidade Estadual de Ponta Grossa, Ponta Grossa, Paraná, Brazil
3
Universidade Do Estado de Mato Grosso, Tangará da Serra, Mato Grosso, Brazil
4
Faculdade UnB de Planaltina-FUP, Brasília, Brazil
5
Ecology Graduate Program, Universidade de Brasília, Brasília, Distrito Federal, Brazil
webs; Ades 1986) building high-quality prey traps is also important. Orb-web spiders are known for their sit-and-wait predation strategy (Foelix 2011), but there are still many questions about which variables most significantly influence the capture of prey in orbicular webs (Herberstein and Tso 2011), and those variables include both web site and web structure. Web site might influence exposure to sunlight, orientation in relation to wind and proximity to other webs. Many insects are attracted to sunlight (Neven 2000),
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