Behaviour 2019
Repeatability of distress signals in the horned bess beetles Odontotaenius disjunctus (Illiger)
Edwin R. Ariza-Marín1, Rafael L. Rodríguez2, Gerlinde Höbel2. 1Instituto de Ecología A.C., Xalapa, Veracruz, Mexico; 2University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, United States

In animal communication, the consistency of individual differences in behavior influences the maintenance of social groupings in various ways. We assessed the repeatability of distress signals in Odontotaenius disjuntus beetles. As other passalids, these beetles form family groups when larvae and adults produce sounds. We recorded 14 females and 7 males, 3 times/day over 3 days. We focused on the following features of the beetles' distress signals: chirp duration and rate, dominant frequency, and amplitude. We also measured body and muscle mass. We estimated repeatability by calculating as the proportion of variance explained by the specimen identity in linear mixed models. We found that chirp duration and chirp rate varied consistently across individuals, whereas only dominant frequency varied with body mass. These results suggest  passalid distress signals may have important functions in their family groupings, and may be useful in systematic analyses.