Oogenesis in a North American population of Aedes (Finlaya) togoi (Theobald) (Diptera: Culicidae)

Abstract

The expression of autogeny in Aedes togoi and its timing are highly variable. Autogenous females, fed 10% sucrose and maintained at 24 °C with a photoperiod of 17.5 h light: 6.5 h dark, developed mature eggs between 5 and 30 days after eclosion. The percent autogeny in a population from Vancouver, B.C., collected as larvae from the field (P1 generation) was 42% ([Formula: see text] eggs/female); the percent autogeny in the laboratory F2 generation, unselected for autogeny, was 40% ([Formula: see text] eggs/female). In the laboratory colony, the process of maturing follicles to the egg stage was frequently delayed. Some females (8%) had mature oocytes on day 5, while 20, 27, and 44% of the female population had mature oocytes on days 6, 8, and 15, respectively. The presence of mature oocytes does not inhibit blood feeding: 17–26% of the females containing mature oocytes took blood, and embarked on a new round of oogenesis. The ovaries of these females contained two separate cohorts of primary follicles, viz., mature oocytes developed autogenously and oocytes developing as a result of the blood meal. Most of the autogenous females with mature oocytes (57–83%) refused blood. This indicates that the presence of mature follicles is a deterrent to feeding and probably to host-seeking. Mating had no effect on the proportion of females that was autogenous.