The Mating Behavior of Byrsotria Fumigata (Guérin) (Blattidae, Blaberinae) 1)

Abstract

In this paper, the first of a series dealing with the mating behavior of cockroaches, the mating behavior of a single species, Byrsotria fumigata, is described in some detail. This species was chosen for first consideration because, among the species studied, it exhibits the basic pattern of cockroach mating behavior in its simplest form with few additions or modifications. Thus, its behavior may be used subsequently as a standard of comparison for that of other species. The pattern as it occurs in this species can be summarized as follows. The primary releaser of the male's courting behavior is the volatile sex attractant or sex pheromone produced by virgin females. Upon perceiving the pheromone, the male shows an alert posture with antennal waving and then rapid locomotion oriented in the general direction of the pheromone source. Antennal contact with the body of a female or the surface of an object impregnated with pheromone releases gentle bumping of the pronotum against the object and wing pumping in a vertical plane. If the female is receptive the pair orient for antennal fencing. The male then raises his wings to the vertical position and simultaneously turns 180 degrees so that he faces away from the female. The female then moves forward straddling the male's abdomen while the male, upon receiving tactile stimulation at the tip of his abdomen, moves backward. The female makes feeding motions with her mouthparts over the dorsal surface of the male's abdomen concentrating on the region of the first abdominal tergite though there appears to be no discreet tergal gland located here as found in various other species. Genital connection is effected in the female-superior position but then the female turns 180 degrees so that the pair assumes an opposed position for the remainder of copulation. Observations were also made on homosexual and pseudofemale behavior among males. Spontaneous courtship among males isolated from females is relatively rare but may be greatly enhanced by placing a source of female sex pheromone in the container of males. A comparison is made between male-male courtship sequences and male-female ones. In addition to the observations of mating behavior, a number of experiments undertaken to elucidate the roles of chemical and tactile stimuli as releasers of the various stages of the mating behavior sequence are described. It was found that, while the female sex pheromone is the primary releaser of the male's courtship behavior, tactile stimulation is required to release some of the later stages of the sequence, particularly the full wing-raising display, and the backing movements and copulatory thrusts of the male.