Nutrient balance affects foraging behaviour of a trap-building predator

Abstract

Predator foraging may be affected by previous prey capture, but it is unknown how nutrient balance affects foraging behaviour. Here, we use a trap-building predator to test whether nutrients from previous prey captures affect foraging behaviour. We fed orb-weaving spiders (Zygiella x-notata) prey flies of different nutrient composition and in different amounts during their first instar and measured the subsequent frequency of web building and aspects of web architecture. We found that both the likelihood of web building and the number of radii in the web were affected by prey nutrient composition while prey availability affected capture area and mesh height. Our results show that both the balance of nutrients in captured prey and the previous capture rate may affect future foraging behaviour of predators.

Figure 1.

Web-building frequency of Zygiella x-notata spiderlings in the beginning of instar II (n = 265). During instar I, spiderlings were fed prey of high (black bars) or low (white bars) nutrient quality in limited or unlimited amounts. (a) Percentage of spiders building a web the first day in instar II. (b) Number of webs produced over the first 3 days of instar II. Means and s.e.'s are shown here for clarity, but statistical analyses were conducted with web counts as an ordinal variable (table 1).

Figure 2.

Web architecture of the second web in instar II by Zygiella x-notata spiderlings (n = 174). During the first instar, spiderlings were fed prey of high (black squares) or low (white squares) nutrient quality in limited or unlimited amounts.