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 fro m parental to 20th generation, the autogenous oviposition capacity cha nged as follows: mean number of egg rafts/female and mean number of eg gs/female increased significantly, from 0.11 to 0.56 and from 6.2 to 2 0.2, respectively; the mean size of the egg rafts decreased significan tly, from 56.2 to 36 eggs/raft; autogeny rates increased significantly , from 18.6 to 65.2%; mean number of autogenous follicles/female decre ased significantly, from 57.4 to 34; the hatching rate of autogenous e gg rafts reduced significantly, from 88.3 to 75.4%; and the feeding ra tes of the females on a blood meal source during the 7th day postemerg ence increased significantly, from 62.8 to 71.1%. The autogeny rate de termined by ovarian dissection was higher than that indicated by actua l 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 succ essively, and scattered ''light color'' egg rafts became more common. Successive en masse selection enhanced autogeny and strengthened the b loodfeeding tendency in this facultative autogenous species.