Behavioral use of equilibrium information by the burrowing cockroach Arenivaga

Date

1989-05

Journal Title

Journal ISSN

Volume Title

Publisher

Texas Tech University

Abstract

Cockroaches in the genus Arenivaga possess specialized sensilla called tricholiths that are found in two rows on the ventral surface of each cercus. Physiological and morphological data suggest that these sensilla monitor changes in the spatial orientation of Arenivaea. However, to show that these sensilla function as gravity receptors, it is necessary to demonstrate that their sensory input affects gravity-dependent behavior. I analyzed the effects of tricholith removal on two such behaviors: geotaxis and compensatory head movements.

The most dramatic effects on geotaxis were produced when more than one row of tricholiths were removed. When all tricholiths were intact, the adult insect was negatively geotactic; however, removal of both lateral rows and one medial row of tricholiths caused significant deviations in geotactic orientation. Furthermore, the insect could not orient geotactically when all tricholiths were removed. Behavioral compensation required a period of at least three weeks, but was observed only following partial tricholith removal. No compensation following removal of all tricholiths was observed.

Arenivaga exhibited compensatory head movements when rolled sinusoidally. Leg activity was not required to elicit these responses. Tricholith removal significantly affected compensatory head movements. For instance, removal of the medial tricholith row on one cercus and the lateral tricholith row on the opposite circus produced destabilizing head movements when the insect was rolled to one side, but not to the other. These abnormal head movements were observed only when the legs of the insect were in contact with a substratum. Destabilizing head movements, produced in response to sinusoidal roll displacements, were not observed when the legs did not touch a surface.

Description

Keywords

Cockroaches, Sense organs -- Insects, Equilibrium (Physiology)

Citation