Sexual cannibalism in a facultative parthenogen: the springbok mantis ( Miomantis caffra )

Abstract

Sexual cannibalism is an extreme expression of sexual conflict, which can grant females significant fitness benefits, particularly if female fecundity depends on foraging success. However, when cannibalism is precopulatory, there is the risk that females remain unmated. Therefore, males simultaneously present the option of a meal or a mate to the females they encounter. The springbok mantis ( Miomantis caffra ) is highly aggressive, and when females cannibalize males, it is exclusively precopulatory. However, females can circumvent the risk of infertility by reproducing asexually, providing a rare opportunity to explore the interaction between sexual cannibalism and facultative parthenogenesis. We kept female mantises on high and low feeding regimes, and paired them with males, to examine how body condition and age influenced rates of cannibalism. We also investigated whether reproductive mode (sexual or asexual) influenced fecundity by measuring ootheca weight. Overall, there was an extremely high average cannibalism frequency (~62%), but no significant difference in frequencies of cannibalism between feeding regimes. Although there was a relationship between female condition and fecundity, influenced by feeding treatment, the mode of reproduction (sexual or asexual) did not result in any difference in ootheca weight. Using information-theoretic approaches, we determined that, of the variables examined, female age best accounted for cannibalistic behavior and that females became less aggressive and more likely to mate over time. This suggests that, although parthenogenesis may allow females to cannibalize males at a high frequency without incurring the cost of infertility, they may still benefit from reproducing sexually later in their lives.