What determines the antipredator strategy in antlion larvae? Burrowing ability decreases the duration of post‐contact immobility

Abstract

For prey exhibiting alternative antipredator strategies, selecting the most effective one is critical for survival. However, what determines such selection remains an open question. We hypothesised that this selection depends on prey skill. We test this idea in Myrmeleon immaculatus De Geer, 1773 (Neuroptera: Myrmeleontidae) antlion larvae that exhibit two alternative antipredator behaviours: post‐contact immobility (PCI) and burying. As the larvae live under sandy soils, PCI is only a temporary strategy, and eventually, all larvae will burrow. However, deciding how long to remain immobile before burying may depend on how fast larvae bury themselves (i.e., how quickly the individual can camouflage itself in the substrate). In a tropical forest from the Yucatan peninsula, Mexico, we measured the PCI duration, bury time and body size of 45 larvae in a fine‐grained experimental substrate. We also measured the mandible length to assess their effects on burying skills. The PCI duration was consistently shorter in larvae that took less time to bury but was longer and more variable in larvae that took more time to bury. This effect was independent of larvae body size. Mandible length did not affect burial time. Our findings suggest that when a given prey should select between two mutually excluding antipredator strategies, the intrinsic skill to perform the most relevant one (how fast burying themselves, in this case) may modulate the duration of the other (PCI, in this case). This reinforces the role of predation as a selective force that modulates prey behaviours.