Sexual Cannibalism Increases Female Egg Production in the Chinese Praying Mantid (Tenodera sinensis)

Abstract

The fecundity benefit of sexual cannibalism is a key parameter of models for the evolution and population-level consequences of sexual cannibalism. Previous studies of praying mantids that have attempted to measure the change in egg production following cannibalism have yielded inconsistent results, possibility due to differences in female ages and background diets. We studied the effect of cannibalism on egg production and egg laying in the Chinese praying mantid (Tenodera sinensis), standardizing female age and mating status, and maintaining females on diets that reflect natural rates of foraging. We experimentally assigned females to one of three treatments: cannibal, non-cannibal, or cricket consumers that received an additional diet of crickets (Acheta domesticus) roughly equivalent to the mass consumed by cannibals. We show that cannibalistic females that consume multiple males produced significantly more eggs and laid more eggs in their first ootheca (egg case) compared to non-cannibals. This result supports the hypothesis that sexual cannibalism in T. sinensis is a female foraging strategy that provides resources to increase fecundity. The increase in egg production by cannibals was similar to that of the cricket consumer females suggesting that male mantids are equivalent to other prey, per unit body mass, in terms of their effects on egg production.