BELANGER, Rachelle M.; MOORE, Paul A.; Bowling Green State University; Bowling Green State University: The utilization of the major chelae by male crayfish (Orconectes rusticus) for detecting female pheromones.

The abundance and spatial distribution of the sensory hairs of the major chelae of the crayfish (Orconectes rusticus) are dependent upon the sex of the crayfish and the reproductive form of the males. Previous studies have also demonstrated that the chelae have both mechano- and chemosensitive properties (Bauer and Hatt 1980; Hatt and Bauer 1980; Altner et al. 1983) and preliminary studies in our lab have shown that reproductively active males will pursue females using their chelae in a chemosensory sampling behavior. Because of this, we wanted to determine if form I (reproductive) male crayfish use chemosensory structures located on their major chelae to detect potential female pheromones in order to initiate mating behavior. These studies should provide a link between the previous morphological studies and reproductive behavior. We videotaped and analyzed the behavioral reaction of form I and II males (N=20) to female conditioned water (N=6), male conditioned water (N=6), and control water. Following this, we used males that had their chelae sensory deprived by coating with super glue. It is thus expected that intact form I male crayfish will spend more time with the female odor source when compared to form II (non reproductive) males and those that are chemosensory lesioned. The significance of this experiment is that it will clarify the role of crayfish chelae in mate localization and courtship behavior and determine if chelae sensory hair distribution and quantity differences seen in form I and II O. rusticus have a reproductive significance. Future research in our lab will help determine if the chemosensory response by the major chelae is an olfactory response.