Habituation of the Light-Startle Response of Orange Head Cockroaches (Eublaberus posticus): Effects of Acclimation, Stimulus Duration, Presence of Food, and Intertrial Interval

The purpose of this paper is to establish the orange head cockroach (Eublaberus posticus) as a useful insect subject for research in comparative psychology by investigating habituation of the light-startle response (LSR). While one goal of comparative psychology is to compare the behavior of a diversity of species, many taxa, including cockroaches, are grossly underrepresented. Our work serves to improve this deficit by investigating habituation learning in the orange head cockroach in four experiments. In our first experiment, we found that LSR, and habituation of LSR, occurs to both lights being turned on and lights being turned off. In our second experiment, we found that the duration of a light did not affect response, and that spontaneous recovery of LSR occurs after 24 h intervals. In our third experiment, we found that the presence of food inhibited LSR. In our final experiment, we found that the rate of LSR habituation decreased as intertrial interval increased, in a manner predicted by established principles of habituation. Our work lays a strong foundation for future research on the behavior of orange head cockroaches as well as learning in cockroaches in general. We hope that our findings help establish cockroaches as practical insect subjects for research in comparative psychology and related fields such as behavior analysis and behavioral ecology.

The Comparative Ontogeny of Social Interactions in Two Species of Cockroach

The ontogeny of social behaviour in two species of cockroach, Shawella couloniana and Eublaberus posticus, was investigated and compared. 1) All acts were recorded in each of 5 age classes per species and the frequencies of each act were calculated and compared. 2) Agonistic intensity increased in Shawella and decreased in Eublaberus with age. 3) Clumping was observed until the last instar in Eublaberus, but never in Shawella, at which time the spacing became regular. 4) Numbers of acts per encounter increased in Shawella and decreased in Eublaberus as a function of age. 5) Initiator-terminated encounters were more frequent in Shawella adults, while responder-terminated encounters were characteristic of all nymphal interactions. In Eublaberus adult males, responder-terminated encounters were most common, but no difference between initiator- and responder-terminated encounters was found in the nymphs. 6) These data were correlated with environmental and life-history parameters in the two species.

CENTRIOLE ADJUNCT DEVELOPMENT IN THE COCKROACH, EUBLABERUS POSTICUS

With electron microscopy it is possible to recognize and describe the development of the centriole adjunct during spermiogenesis of the cockroach, Eublaberus posticus, an orthopteran insect. The four stages identified may be classified as: (1) presumptive granular stage; (2) endoplasmic reticulum associated stage; (3) ordered granular and vacuolate stage; and (4) mature stage. A description of the four stages of the centriole adjunct development, one in a spermatocyte, two in a spermatid and a fourth in the mature stage, suggests some possible origins of this structure and gives a detailed description of its development.