The ovarian condition of certain sylvan mosquitos in Uganda (Diptera, Culicidae)

Abstract

This paper records the ovarian condition of sylvan Culicine mosquitos caught resting and biting in Uganda. Information provided for the commoner species includes Sella's stages of blood-digestion, Christophers' ovarian stages (modified) for nullipars and pars, and sac stages for pars.The distribution of Sella's stages among resting populations indicates that the several species differ widely in the resting sites chosen by blood-fed females. Among the species studied, Mansonia, fuscopennata (Theo.), M. africana (Edw.), M. uniformis (Theo.) and Culex annulioris Theo. are unusual in that many females probably rest outside forest after a blood-meal.The ovarian stage in which nullipars and pars come to bite is often characteristic of a species. Nullipars and pars of one species may bite in the same ovarian stage, or in different stages. In species of Mansonia (Coquillettidia) nullipars are typically more advanced than pars, apparently because there is extensive use of food reserves which are exhausted before the first blood-meal; in such species ovarian development can also be discerned in pars between oviposition and a blood-meal, but it is extremely slight. In certain Aedes (subgenera Finlaya and Stegomyia), pars are typically more advanced than nullipars, and among those studied here it is only species of this type which to any extent show the pattern long regarded as normal in Anophelines. Wide variation in ovarian stages of biting nullipars of Aedes raises the possibility that limited autogeny may exist in some of the species studied.