PATTERNS OF SPERM COMPETITION INNASONIA VITRIPENNIS

Females of the parasitic wasp, Nasonia vitripennis Walker, were generally nonreceptive after the initial copulation. But if they were inseminated twice, once by each of two virgin males in quick succession, they seldom retained for utilization any sperm from the second mate. If both males, or first males only, were partially depleted of sperm by prior copulations, then sperm from both males were often retained and utilized daily throughout a two- to three-week laying period. Sperm mixing resulted in random usage or in initiai preferential usage from either the first or second male. Precedence in usage of sperm from one mutant (oy) is suggested. When groups of males competed for females, some of the females were not inseminated and some others were doubly inseminated.