Meeting Abstract

25.6  Sunday, Jan. 4 14:30  Comparative study of cercal system sensory processing across three cockroach species that vary in their wind-mediated behavioral responses. TRIBLEHORN, JD; College of Charleston, South Carolina

The wind-sensitive insect cercal sensory system is involved in important behaviors including predator detection and initiating terrestrial escape responses as well as flight maintenance. However, not all insects possessing a cercal system exhibit these behaviors. In cockroaches (Blatteria), wind evokes strong terrestrial escape responses in Periplaneta americana, but only weak escape responses in Blaberus craniifer, and no escape responses in Gromphadorhina portentosa. Both P. americana and B. craniifer possess pink flight muscles correlated with flight ability while G. portentosa lacks wings. These different behavioral combinations could correlate with differences in sensory processing of wind information by the cercal system. Using extracellular recordings, we investigated whether such differences existed by characterizing the responses from the filiform afferent and wind-sensitive interneuron (WSI) populations to different wind velocities. We also compared these responses to examine information transfer at the first synapse. Our main results were: 1) wind elicited the weakest afferent and WSI responses in G. portentosa, which also possessed the smallest cerci with the least filiform hair receptors; 2) B. craniifer afferent and WSI responses were similar to or greater than responses in P. americana even though B. craniifer possessed smaller cerci with less filiform hair receptors than P. americana; 3) the greater filiform afferent responses in B. craniifer, including a larger amplitude second positive peak compared to the other two species, suggest more synchronous activity between filiform afferents in this species; 4) the transfer of information at the first synapse appears to be similar in both P. americana and G. portentosa, but different in B. craniifer.