Studies on autogeny in Culex tarsalis: 2. Simulated diapause induction and termination in genetically autogenous females.

Exposure to simulated "mid-winter" conditions (16 degrees C, 10L:14D) inhibited the expression of autogeny among the female progeny of field-collected Culex tarsalis females. The same F1 progeny expressed 43% autogeny when reared in an insectary under simulated "summer" conditions (25 degrees C, 16L:8D). Diapausing F1 progeny did not express autogeny after a 42-day simulated winter or after diapause termination periods of 4 days in the insectary or 29 days outdoors during January. Females were then blood fed and the progeny reared in the insectary; autogeny rates among F2 females in 4 families ranged from 0 to 43%. Autogeny rates among females emerging from pupae collected during March at 2 localities in Kern County, California were 15 and 17%. Diapause was not induced uniformly among females from a laboratory-selected autogenous colony. Autogeny rates before and after a simulated winter period did not change significantly.