Context-dependent effects on attack and defense behaviors in the praying mantis Tenodera sinensis

Most behavior needs to strike a balance between the competing needs to find food and protect an animal from predators. The factors that influence this balance and the resulting behavior are not well understood in many animals. Here, we examined these influences in the praying mantis Tenodera sinensis by presenting perching individuals with alternating sinusoidally moving prey-like stimuli and rapidly expanding looming stimuli then scoring their behavior on a defensive-aggressive scale. In this way, we tested the hypothesis that such behaviors are highly context dependent. Specifically, we found that defensive responses, which are normally very consistent, are decreased in magnitude if the animal has just performed an aggressive response to the previous sinusoid. A thrash behavior not normally seen with looming alone was often seen following aggression. In thrashing, the animal tries to push the looming stimulus away. Thrashing almost exclusively followed aggressive responses to the sinusoid stimulus. Moreover, aggression levels were found to shift from low to high and back to low as adult animals aged and, in general, female mantises were more aggressive than males. Finally, the specific nature of the mid-life spike in aggressive behaviors differed according to whether the animals were lab raised or caught in the wild. Lab-raised animals showed roughly equal amounts of increased attention to the stimulus and very aggressive strike behaviors, whereas wild-caught animals tended to either ignore the stimulus or react very aggressively with strikes. Therefore, our hypothesis regarding context-dependent effects was supported, with all four factors influencing the behaviors that were studied.