Ignorando o custo-benefício: o forrageio de aranhas Trichonephila clavipes sob risco de predação independe da condição nutricional e da disponibilidade de presas

Abstract

Generally, predator foraging is influenced by the availability of food in their environment. Prey foraging, on the other hand, depends on both food availability and predation risk. However, within the trophic chain, predators can be classified as either top or intermediate. Since intermediate predators may be preyed upon by top predators, their foraging should also be influenced by both food availability and predation risk. In sit-and-wait intermediate predators, the pressure exerted by top predators may lead to the abandonment of their foraging activity. However, not only the abundance of top predators can modulate the foraging decisions of intermediate predators, but also other environmental factors such as prey abundance. Furthermore, individual characteristics, such as the predator’s nutritional condition, may also influence its foraging decisions. Sit-and-wait intermediate predators in poorer nutritional condition may return to foraging more quickly, especially when they detect the presence of prey nearby, due to their greater energetic demands. Thus, the time spent without foraging may vary according to nutritional condition and prey availability. In this study, we used females of the spider Trichonephila clavipes (Linnaeus, 1767) (Araneae: Araneidae) to test the hypothesis that individuals in poorer nutritional condition return to foraging more quickly after a predatory attack, especially when prey are available in the web. To this end, we simulated predatory attacks in two groups of spiders, with (n = 32) and without prey addition (n = 36). Escape was measured as the probability of spiders moving to the periphery of the web or surrounding vegetation, and return was measured as the probability of returning to the center of the web within 120 s. We estimated body fat as an indicator of nutritional condition. Our results indicate that both behaviors were independent of nutritional condition and prey presence. Although the spiders prioritized reducing immediate predation risk, the lack of influence from food availability and body condition suggests that other factors, such as personality or previous experiences, may be more relevant to the behavioral decisions of T. clavipes. This highlights the importance of considering multiple sources of individual and environmental variation to understand the foraging behavior of intermediate predators.