The role of copulatory plugs in mosquito-parasitic nematode Strelkovimermis spiculatus

The mosquito-parasitic nematode, Strelkovimermis spiculatus (Mermithidae: Nematoda) emerges from hosts and aggregates to form mating clusters characterized by intense male-male competition for females. Successful males deposit a copulatory plug over the female vulva after mating. In choice experiments, males strongly preferred virgin females, whereas plugged females were ignored. Males were not observed attempting to remove the plug nor endeavoring to mate. Females with a copulatory plug repelled males. The observed chemical repellency was independent of females, since excised plugs alone showed the same negative male response. The plug contributes significantly to female fitness because removal of the plug after mating was found to reduce fecundity by 90%. About average of 805 spermatids were found to leak out from a female in the first 2 h after plug removal. Our initial hypothesis that the plug provides a nutritional gift was rejected due to the fact that there was no post-mating reduction in plug size that would have indicated absorption.M.S.Includes bibliographical referencesby Yu-Han La