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

Abstract

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.

Venom gland size and venom complexity—essential trophic adaptations of venomous predators: A case study using spiders

“…Instead, it may indicate that their venom contains components that are very effective in immobilizing prey in small amounts. Existence of such compounds is further supported by the absence of an ontogenetic shift in prey preference (from small to large prey) and the venom complexity in ant‐eating specialists reported so far (Cárdenas, Šedo, & Pekár, ): Even tiny spiderlings were able to subdue ants that were dozens of times larger than themselves with a single short bite (Pekár et al., ).…”

Venom of prey‐specialized spiders is more toxic to their preferred prey: A result of prey‐specific toxins

“…In the case of spiders, similar evidence exists and is most frequently based on observations of the more rapid paralysis of preferred prey (Heller, ; Jackson & Whitehouse, ; Jarman & Jackson, ; Pekár, Král, & Lubin, ; Pekár, Petráková, et al., ). This hypothesis is also supported by the lack of ontogenetic shifts in prey preference and venom composition in specialist spiders (Cárdenas, Šedo, & Pekár, ; Pekár, Šedo, Líznarová, Korenko, & Zdráhal, ). In fact, this hypothesis is in agreement with the fact that the whole arsenal of venoms employed by specialists is less diversified than the venoms used by generalists (Phuong, Mahardika, & Alfaro, ) because it mainly contains components which are used to target selected prey.…”

The onset of piscivory in a freshwater fish species: analysis of behavioural and physiological traits

“…Ontogenetic changes in predatory behaviour are not necessarily essential for generalist predators, which can exhibit different behavioural tactics of capture due to the high variability in prey and can shift to another prey type without having to learn a new tactic quickly (Cárdenas et al ., 2014). Conversely, a specialist‐like species must deal with the shift to a new prey type.…”