Opportunities

The literature to date suggests the taxa with the most promise for potentially productive studies of sexual selection occur within the Blattellidae, the largest but least known family of cockroaches. Males in this family vari ably possess diverse complex intromittent genital structures, elaborate tergal glands, uricose glands, and the most variable testes of examined species (Ph.D. thesis by E.R. Quiaoit, cited by Roth, 1970a). Females can have multiple spermathecae; furthermore, their reproduction can be closely tied to food availability, as they invest a high proportion of their bodily reserves into each reproductive event. The existence of these elaborate morphological structures, together with both prenuptial feeding via tergal glands and postnuptial feeding via uricose glands may be red flags signaling that male and female reproductive interests do not coincide. The potential for reproductive conflict is great when males provide nuptial gifts, because females are selected to obtain an optimal supply of nutrients, while males are selected for those traits that assure she uses his sperm (Thornhill and Alcock, 1983). The possession of morphologically complex, multiple sper-mathecae in females and a variety of intromittent-type structures in males suggest that control of sperm use in some blattellids may be an evolutionary chess game played out inside the female body during and after copulation. Blattellids as well as other cockroach taxa, then, are potentially rich sources of research material for a wide range of studies on insect mating strategies. Can the number of spermathecae or their structure be correlated with the morphology of any of the "blades" on the male's Swiss army knife? Do elaborate spermathecae occur only in species with male uricose glands? Do complex male genital structures influence female sperm use, and if so, how do they do it? Does the quantity or composition of tergal secretion influence female choice? Are complex tergal glands and the possession of uricose glands correlated? Does the amount of uric acid transferred after copulation influence female sperm acceptance and use? It is clear that the scope of research needs to be expanded beyond the domestic pets and pests typically kept in laboratories, with an increased emphasis on bringing field and laboratory work into closer alignment. Even so, the study of sexual selection in cockroaches is in its early stages, despite the opportunities offered by even the most easily obtained and studied species. What is the function of giant sperm in Periplaneta? Do female American cockroaches preferentially use sperm from the capsular branch of the spermatheca? Is there differential use of the sperm from the four spermathecal chambers of German cockroaches? If so, is the male virga involved in influencing female sperm choice decisions? A creative scientist capable of overcoming the technical challenges inherent in these kinds of studies could be amply rewarded.

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