Is there ontogenetic shift in the capture traits of a prey-specialized ant-eating spider?

Predators have to deal with the problem of prey shifting during predator's ontogenesis. The ontogenetic shift in the prey capture of prey‐specialized species should be associated with a change in their predatory traits. Here, we focused on the ant‐eating Zodarion rubidum, a spider strictly specialized on ants. It uses potent venom to immobilize prey. We tested whether there is a change during the ontogenesis of the spider species in traits related to capture efficiency. We kept spiders from the juvenile to adult stage on a monotypic diet composed of one of four ant species, small and large ant species from two subfamilies. We tested the capture efficiency of all spiders at the beginning and at the end of the experiment after being reared on a certain ant species, and then we swapped the spiders and tested them with the other ant species. For each trial, we measured the number of attacks (bites) and the paralysis latency. Afterwards venom glands were extracted and analysed using MALDI‐TOF mass spectrometry and 1D‐SDS‐PAGE gel electrophoresis. We found that spiders on all diets improved their capture efficiency during ontogenetic development. We hypothesize that the improvement was due to an increase in the amount of venom injected. Thus, we did not find an ontogenetic shift in the predatory traits. Nor was there a significant difference in the composition of low and high molecular weight venom compounds among diet groups, suggesting that the consumption of a prey has little effect on venom composition.