Collaborative Research: Modulatory Role of Central Complex Brain Systems in Context Dependent Predation of Three Mantis Species

Case Western Reserve University, Cleveland OH

Investigators

Abstract

Animal behavior is affected by an individual's internal conditions. For example, as animals feed, their strategies for acquiring food changes. The impact of food odors has a very different effect on a hungry person than one who has just had a large meal. This project brings together laboratories from the Case Western Reserve University Biology department and the Cleveland Museum of Natural History to examine changes in hunting strategy that occur as praying mantises feed. The biology laboratory will examine changes in brain systems that control movement as the insect feeds or receives injections of hormones associated with feeding. Insects provide advantages for monitoring brain activity for long feeding periods. Results will demonstrate how brain systems that are altered by hormones associated with feeding affect hunting and will increase our general understanding of the mechanisms by which hormonal changes alter animal behavior. The museum laboratory will expand the study to a wider range of praying mantis species. The project also has a unique educational component. Project related material will be developed into new high- and middle-school teaching modules for the Cleveland Museum of Natural History's award winning distance learning program, which has reached thousands of students in 48 states. These programs align with Ohio's New Learning Standards. Modules will be offered for free for the duration of the project and 3 subsequent years. The project focuses on the highly structured central complex insect brain region that has received much recent attention. Numerous forms of sensory information coupled with motor effects and the presence of behaviorally relevant neuromodulators imply an important role for the central complex in behavioral adaptation. Yet, no study has brought all these components together to demonstrate how these brain circuits generate context dependent adjustments in natural behavior. This project seeks do that by relating changes in praying mantis hunt strategies to central complex activity patterns recorded by multi-channel tetrode implants as the hunt takes place in one generalist and two specialist praying mantis species. Tetrode wires will be implanted in the insect's central complex. Then after recovery the subject will be moved to an arena where it hunts either live prey (cockroach nymphs) or artificial prey (moving dots on a computer screen that makes up the floor of the arena). The artificial stimulus allows repeated trials to provide quantitative data on neural activity associated with hunting. Neural and behavioral changes will be documented as physiological state is modified by feeding or insulin injection. Comparative studies will clarify how evolution acts on brain structures to shape behavior for specific niches. Successful completion will be transformative both in our understanding of the central complex's role in behavioral adjustment and, more generally, in defining mechanisms by which brain regions in all animals can alter adaptive behavior, thereby establishing the praying mantis as a new general model for behavioral selection.