Selection-dependent trends of autogeny and blood feeding in an autogenous strain of Culex tarsalis (Diptera:Culicidae).

During successive en masse selection of autogeny in Culex tarsalis from parental to 20th generation, the autogenous oviposition capacity changed as follows: mean number of egg rafts/female and mean number of eggs/female increased significantly, from 0.11 to 0.56 and from 6.2 to 20.2, respectively; the mean size of the egg rafts decreased significantly, from 56.2 to 36 eggs/raft; autogeny rates increased significantly, from 18.6 to 65.2%; mean number of autogenous follicles/female decreased significantly, from 57.4 to 34; the hatching rate of autogenous egg rafts reduced significantly, from 88.3 to 75.4%; and the feeding rates of the females on a blood meal source during the 7th day postemergence increased significantly, from 62.8 to 71.1%. The autogeny rate determined by ovarian dissection was higher than that indicated by actual oviposition. As the age of females increased during the observed 10-day oviposition period, the mean number of egg rafts/female, the mean number of eggs/female, and the mean number of eggs/raft decreased successively, and scattered "light color" egg rafts became more common. Successive en masse selection enhanced autogeny and strengthened the bloodfeeding tendency in this facultative autogenous species.