Postcopulatory sexual selection in the soldier fly Merosargus cingulatus

There is substantial evidence that cryptic female choice (CFC) is present in numerous taxa. Several mechanisms have been proposed for CFC; however, we only have experimental evidence for a few of them. Female control of oviposition timing is a potentially widespread mechanism of CFC, but it has never been experimentally demonstrated. The aims of this study are to test two critical predictions of the hypothesis that CFC through control of oviposition timing occurs in the soldier fly Merosargus cingulatus: (1) to determine if M. cingulatus females are less likely to oviposit immediately after mating when the male does not perform copulatory courtship than when he does; and (2) to determine if failure to immediately oviposit by the female results in lower reproductive success for the male she just mated with. To answer the first question, I compared the oviposition behavior of females that mated with control males versus females that mated with manipulated males that could not perform copulatory courtship. I showed that M. cingulatus females fail to oviposit immediately following copulation when males do not perform copulatory courtship. To answer the second question, I showed that there is last male sperm precedence in M. cingulatus. Since the last male to mate fertilizes most of the female’s eggs, a male will benefit when females oviposit immediately after mating with him and before remating with another male.