Sexual Isolation between Populations of the Culex pipiens Complex in North America

Abstract

The purpose of this study was to determine whether mating barriers could function as a mechanism of isolation between populations of Culex pipiens. C. quinquefasciatus and C. molestus in North America. In mating selection experiments, males were given the opportunity to mate with their own females or with females belonging to another population. In non-selection experiments, males of one population were placed in contact with females of only one kind. The criterion of successful mating was considered to be the presence of sperm in the spermathecae. These experiments did not reveal an ability on the part of the members of these populations to recognize the opposite sex of their own kind. Differences in insemination rates appeared to be the result of varying degrees of sexual activity exhibited by these populations under identical laboratory conditions. It is possible that differential sexual activity might be a means of keeping these populations separate from one another in their natural environments. However, it is believed that the results of these experiments do not warrant the conclusion that C.pipiens, quinquefasciatus. and molestus in N. America are of more than subspecific status.