A new component of the female sex pheromone ofBlattella germanica (L.) (Dictyoptera: Blattellidae) and interaction with other pheromone components.

A fourth component, 3,11-dimethyi-2-heptacosanone, was identified as a cuticular contact sex pheromone of the female German cockroach,Blattella germanica. In behavioral assays, higher dosages of 3,11-dimethyl-2-heptacosanone were needed to elicit similar sexual responses in males to those elicited by the major pheromone component, 3,11-dimethyl-2-nonacosanone. A 15∶85 blend of the C27 and C29 methyl ketone homologs resulted in a dose-response curve intermediate between that of each of the components alone, indicating independence of activity of each component and lack of synergism. Moreover, the activity of 3,11-dimethyl-2-nonacosanone was not enhanced by female cuticular hydrocarbons. The relationship between sexual responses of males to females and to isolated female antennae, and the amount of cuticular pheromone on whole females was investigated. Cuticular sex pheromone found on females increased with the age of the female, as did the male response to whole females. However, a bimodal male response was elicited by isolated female antennae. Differences between behavioral and analytical assays of pheromone are discussed.