Prey handling of toxic and non-toxic Lepidopteran prey by the Chinese mantid, Tenodera sinensis

Monarch caterpillars, Danaus plexippus, sequester toxic cardenolides from milkweed plants. This defense is effective against most predators, but the Chinese mantid, Tenodera sinensis, is able to consume them without any apparent ill effects. It has been shown that mantids consume monarch caterpillars by gutting them, allowing the gut material to fall from the prey without further attempt to consume it. They do not engage in this behavior when consuming non-toxic European corn borers, Ostrinia nubilalis, or wax worms, Galleria mellonella, suggesting avoidance of prey toxicity. It may also be avoidance of more toxic/less nutritive plant material, since mantids are consuming cardenolides even when feeding only on the body of toxic monarchs. We furthered this research by rearing monarch caterpillars and cabbage loopers, Trichoplusia ni, on toxic and non-toxic plants, and conducting behavioral trials observing mantid predator-prey encounters with these prey. In addition, we offered mantids starved and un-starved monarch caterpillars reared on toxic and non-toxic plants as well as corn borers.

Mantids gut both toxic and non-toxic monarch caterpillars and cabbage loopers, but not starved monarchs (gut clear of plant material). This suggests that the gutting behavior likely reflects a general avoidance of plant material. Intriguingly, mantids did not gut corn borers that recently fed on corn kernels. This may indicate that the mantids respond differently to caterpillars that ingest plant material of different nutrient content (seeds vs. leaves). We plant to run a CNH analysis on collected gut and body material as well as food source to test this.