King B H, Seidl S E
Department of Biological Sciences, Northern Illinois University, 60115, DeKalb, IL, USA.
Oecologia. 1993 Jun;94(3):428-433. doi: 10.1007/BF00317119.
This study examines the sex ratio response of the parasitoid wasp Muscidifurax raptor to conspecific and confamilial females in relation to two groups of functional sex ratio models, local mate competition and host quality models. In some but not all experiments, M. raptor females produced a greater proportion of sons in the presence of a conspecific female than when alone, and this sex ratio effect carried over for a day after the females were isolated from each other M. raptor females also produced a greater proportion of sons in the presence of a female of the confamilial parasitoid Spalangia cameroni than when alone (although only on the second day of exposure to S. cameroni, not on the first). M. raptor's sex ratio increase in the presence of conspecifics is consistent with local mate competition models but not with host quality models because the presence of a conspecific female did not cause there to be more, and thus potentially smaller, offspring developing per host. In contrast, the presence of a S. cameroni female did cause there to be more offspring developing per host than when a M. raptor female was alone; thus M. raptor's sex ratio increase in the presence of S. cameroni may be explained by host quality models. An alternative explanation for the sex ratio increase in response to confamilials is that only a sex ratio response to conspecifics may be adaptive, due to local mate competition; but M. raptor females may be unable to distinguish between conspecific and S. cameroni females.
本研究考察了寄生蜂猛禽厩螫蝇（Muscidifurax raptor）对同种和同属雌性的性别比例反应，这与两组功能性性别比例模型相关，即局部配偶竞争模型和寄主质量模型。在部分而非全部实验中，与单独存在时相比，猛禽厩螫蝇雌性在有同种雌性存在时产生的雄性后代比例更高，并且在雌性彼此分离后的一天内，这种性别比例效应仍然存在。猛禽厩螫蝇雌性在有同属寄生蜂卡梅伦斯氏斯帕兰吉亚蜂（Spalangia cameroni）雌性存在时，产生的雄性后代比例也比单独存在时更高（尽管仅在接触卡梅伦斯氏斯帕兰吉亚蜂的第二天出现这种情况，第一天未出现）。猛禽厩螫蝇在同种存在时性别比例增加，这与局部配偶竞争模型相符，但与寄主质量模型不符，因为同种雌性的存在并未导致每个寄主上发育的后代更多，进而潜在地更小。相比之下，卡梅伦斯氏斯帕兰吉亚蜂雌性的存在确实导致每个寄主上发育的后代比猛禽厩螫蝇雌性单独存在时更多；因此，猛禽厩螫蝇在卡梅伦斯氏斯帕兰吉亚蜂存在时性别比例增加可能由寄主质量模型来解释。对同属个体性别比例增加的另一种解释是，由于局部配偶竞争，可能只有对同种个体的性别比例反应才具有适应性；但猛禽厩螫蝇雌性可能无法区分同种和卡梅伦斯氏斯帕兰吉亚蜂雌性。
