Differences in prey handling of larval and adult monarchs, Danaus plexippus, by Chinese Mantids, Tenodera sinensis

Prey use a variety of anti-predator defenses to increase survival. In herbivores, one such defense involves the consumption and subsequent sequestration of toxins as an anti-predator defense. One well-known example of this defense is the monarch caterpillar, Danaus plexippus, which sequesters toxic cardenolides from plants in the genus Asclepias. While this defense is normally effective, previous research shows that Chinese mantids, Tenodera sinesis, can partially consume them without any apparent ill-effects. The mantid eats the monarch caterpillar’s skin but does not consume its gut content, allowing it to fall from the prey. In contrast mantids consume nontoxic European corn borers, Ostrinia nubilalis, and waxworms, Galleria mellonella, in their entirety. To further understand mantid responses to chemically-defended prey, we conducted behavioral assays in which we observed the behavior of naïve mantids presented with ‘toxic’ (raised on cardenolide-rich A. syriaca) or ‘non-toxic’ (raised on no-cardenolide A. incarnata) monarch caterpillars and adults.

Mantids handled toxic and nontoxic prey similarly, but handled caterpillars and adult butterflies differently. They always gutted both toxic and nontoxic caterpillars, but never gutted adult butterflies. Instead, they consumed the body of the butterflies and discarded the wings, legs, and antennae. These results indicate that mantids treat prey life stages differently and may be avoiding plant matter within prey gut. Future experiments into this complex predator-prey interaction should research the underlying mechanisms controlling this mantid behavior.