Aversion for bitter taste reveals sexual differences in alimentation strategies in a praying mantis

Insects, as well as vertebrates, possess morphological, physiological and behavioural sexual dimorphisms. Because they are commonly bigger and produce eggs, female insects usually require more and specific energy intake. In addition to quantitative and qualitative requirements in food for reproduction, animals also have to avoid eating lethal toxins. The praying mantis Tenodera aridifolia is a good model to investigate sexual differences in feeding behaviour because its sexual dimorphism is marked in terms of morphology and behaviour. Here, we observed that females ate approximately four times as much prey as males. We then investigated the attacking and feeding behaviours of praying mantises by presenting mealworms injected with bitter solutions (quinine hydrochloride dihydrate or denatonium benzoate at 50 or 500 mM) as prey. We observed that males had a low level of acceptance for bitter prey: unlike females, they reduced consumption of mealworms injected with 50 mM of these bitter solutions. However, they showed higher motivation (unlike females, their rate of attack on prey increased when they reduced their consumption of mealworms). This difference in ingestion between the sexes did not seem to be due to different sensitivities for these bitter solutions (there was no detectable difference between the sexes in time taken to drink drops of these bitter solutions). Instead, this seems related to males and females having different feeding strategies based on different nutritive requirements. The possible effects of nutritional composition of prey on avoidance behaviours in predatory insects are discussed.