CALLING BEHAVIOR OF THE FEMALE GERMAN-COCKROACH, BLATTELLA-GERMANICA (DICTYOPTERA, BLATTELLIDAE)

Virgin German cockroach females, Blattella germanica (L.), were observ ed, for the first time, to exhibit a characteristic calling behavior d uring which females emit a volatile sex pheromone. Under a photoperiod of 12L:12D, the percentage of 7-day-old virgin females that exhibited this behavior peaked before the end of the scotophase in a similar pa ttern to the diel periodicity of mating. A clear relationship was evid ent between calling and stages of sexual receptivity during successive gonotrophic cycles. Females initiated calling 5-6 days after the imag inal molt, when their basal oocytes were 1.6 nun long. If not mated, f emales continued to exhibit bouts of calling during the next 3-4 days until 24 h before ovulation. Calling was completely suppressed by mati ng as well as the presence of an egg case in the genital atrium in bot h virgin and mated gravid females. We suggest that calling and the emi ssion of a volatile sex pheromone serve to attract males from a distan ce as well as to potentiate responses to contact sex pheromone in aggr egations.