Morphology of the sternal and tergal glands producing the sexual pheromones and the aphrodisiacs among the cockroaches of the subfamily oxyhaloinae.

Abstract

Among cockroaches in the subfamily of Oxyhaloinae, the adult males produce two essential and successively active chemical signals: the sex pheromone attracting females from a distance secreted by the sternal glands, and the aphrodisiac required for mating which is secreted by the tergal glands. The adult males of the seven species studied, Nauphoeta cinerea, Henschoutedenia flexivitta, Leucophaea maderae, Jagrehnia madecassa, Gromphadorhina portentosa, G. laevigata, and G. chopardi, possess well-developed sternal and tergal glands whose number varies according to the species and methods of mating (three to six sternal glands and four to seven tergal glands). These glands are basically composed of type three glandular units (glandular cell + duct cell) and type 2 cells (modified oenocytes) which exhibit no significant external cuticular modification except for tergite 2 of L. maderae. The extreme variance in development of these glands can be linked to sexual behavior. The hypothesis put forward here is that of a regressive evolution of the tergal glands, related to a modification of the role played by the aphrodisiacs which they secrete.