ALTERNATIVE SCHEDULES OF MALE REPRODUCTIVE DIAPAUSE IN THE GRASSHOPPER ANACRIDIUM-AEGYPTIUM (L) - EFFECTS OF THE CORPORA ALLATA ON SEXUAL-BEHAVIOR (ORTHOPTERA, ACRIDIDAE)

We studied the ontogeny of male sexual behavior in laboratory cohorts of the grasshopper Anacridium aegyptium to understand how male and female sexual activity is synchronized in this species. Contrary to previous accounts, certain male A. aegyptium undergo an extended period of reproductive diapause and do not show an onset of sexual behavior until several months postfledging. Considerable variation in diapause length existed, however, and some males showed onsets as early as 21 days postfledging, probably a nondiapause condition. A series of allatectomies and implantations of corpora allata (CA) demonstrated that male sexual behavior was dependent upon the presence of "active" CA and indicated that the periods of natural refractoriness noted above were related to inactive CA. In some cohorts, male longevity was extended in allatectomized individuals or in those exhibiting lengthy reproductive diapause. We speculate that variable diapause periods may represent a "bet-hedging" strategy of the parental generation selected for by two opposing pressures: the uncertainty of extended survival, selecting for brief periods, and intermale competition in the form of sperm precedence, favoring lengthy diapause.