Internal state effects on behavioral shifts in freely behaving praying mantises (Tenodera sinensis)

How we interact with our environment largely depends on both the external cues presented by our surroundings and the internal state from within. Internal states are the ever-changing physiological conditions that communicate the immediate survival needs and motivate the animal to behaviorally fulfill them. Satiety level constitutes such a state, and therefore has a dynamic influence on the output behaviors of an animal. In predatory insects like the praying mantis, hunting tactics, grooming, and mating have been shown to change hierarchical organization of behaviors depending on satiety. Here, we analyze behavior sequences of freely hunting praying mantises (Tenodera sinensis) to explore potential differences in sequential patterning of behavior as a correlate of satiety. First, our data supports previous work that showed starved praying mantises were not just more often attentive to prey, but also more often attentive to further prey. This was indicated by the increased time fraction spent in attentive bouts such as prey monitoring, head turns (to track prey), translations (closing the distance to the prey), and more strike attempts. With increasing satiety, praying mantises showed reduced time in these behaviors and exhibited them primarily towards close-proximity prey. Furthermore, our data demonstrates that during states of starvation, the praying mantis exhibits a stereotyped pattern of behavior that is highly motivated by prey capture. As satiety increased, the sequenced behaviors became more variable, indicating a shift away from the necessity of prey capture to more fluid presentations of behavior assembly.Author summary: Animals have the incredible ability to adapt behavior to the task at hand. Such an ability is born, in part, from the biochemical modulation of neural networks to contextually integrate sensory information and formulate appropriate behavioral responses. Satiety hormones—and more specifically insulin—have this modulatory effect on various brain regions via strikingly conserved mechanisms across the animal phyla. Like vertebrates, invertebrates have shown impressive abilities to thrive in diverse environments—showing sophisticated adaptive abilities that make these animals more than the “lowly animals” their reputation would make you believe. In this work, the effect of satiety on output behavior of freely hunting mantises was assessed. It was found that in food deprived states, mantises exhibited more stereotyped behavior sequences, with the primary motivation of prey capture. Conversely, as satiety increased, behavior sequences became more flexible. This work suggests that behavior assembly takes on a more rigid structure in times of desperation, when survival of the animal is at stake. The increase in satiety correlates to a change in the hierarchical schema of behavior such that when food is secured, behavior takes a more free-form structure.