Most cockroaches that have been studied rely on chemical and tactile cues to find their mates in the dark (Roth and Willis, 1952a). In many cases volatile sex pheromones mediate the initial orientation; these have been demonstrated in 16 cockroach species in three families. The pheromones are most commonly female generated and function at a variety of distances, up to 2 m or more, depending on the species (Gemeno and Schal, 2004). Females in the process of releasing pheromone ("calling") often assume a characteristic posture (Fig. 6.1): they raise the wings (if they have them), lower the abdomen, and open the terminal abdominal segments to expose the genital vestibulum (Hales and Breed, 1983; Gemeno et al., 2003). In some species the initial roles are reversed, with males assuming a characteristic stance while luring females (Roth and Dateo, 1966; Sreng, 1979a). A calling male may maintain the posture for 2 or more hr, with many short interruptions (Sirugue et al., 1992). Based on the limited available data, the general pattern appears to be that in species where the male or both sexes are volant, females release a long-range volatile pheromone. Males release sex pheromones in species where neither sex can fly (Gemeno and Schal, 2004).
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