Intriguing compensation by adult female spiders for food limitation experienced as juveniles

Abstract

We conducted a field experiment to test for food limitation in immature stages, and its consequences for mature females, in the territorial, cannibalistic spider Lycosa tarentula (L.). Randomly selected antepenultimate juveniles were provided supplemental prey until they matured, at which time supplemental feeding ceased. Immature stages of L. tarentula are food‐limited. Supplemented juvenile spiders decreased foraging activity, disappeared at a lower rate and grew faster than the control spiders, which had been exposed only to ambient prey levels. Fed juvenile females were less hungry at maturity, as judged by an index of body condition, and showed higher mating success as adults, as judged by cohabitation rates with mature males. Foraging theory predicts that in order to compensate for residual effects of food limitation, adult female spiders that had experienced a shortage of prey as juveniles – the controls – would have to exhibit a greater increase in foraging activity upon maturing than the prey‐supplemented group. Contrary to expectation, the control females did not increase their foraging activity, but the previously fed females did forage more actively as adults. Furthermore, the difference in mass gain during the mating period between the two groups was opposite from what the difference in change in foraging activity would predict. Control females, the spiders that had not changed their foraging activity, gained mass more rapidly than the previously fed females, with the result that the two groups were similar in mass by the end of the mating period. We hypothesize that an increased rate of sexual cannibalism may have been one mechanism by which control females compensated for the food limitation that they had experienced as immatures.