Culicoides sonorensis (Wirth & Jones) (Diptera: Ceratopogonidae) adults were active from May through October during 2002-2006 in southern Alberta, Canada. Adults were first captured in May, and populations peaked in early June, late July, and late August. The first population peak occurred when mean weekly temperatures exceeded 16 degrees C, resulting in a variable amount of time for spring emergence. This asynchrony in spring emergence accounted for much of the annual variation in timing of subsequent population peaks. Peaks were separated by an average of 6-7 wk. C. sonorensis seems to have one overwintering generation and two generations during the summer. Abundance was correlated among sites located up to 90 km apart. Abundance at a rangeland site increased more rapidly with mean weekly temperatures than at feedlot sites. The proportion female ranged from 0.68 to 0.83 but showed no consistent differences between rangeland and feedlot sites. The proportion female declined with distance from a developmental area at the rangeland site. Proportion parous was similar among rangeland and feedlot sites, and it also declined with distance from a developmental area at the rangeland site. The proportion parous increased early in the season, fluctuated throughout the mid-season, and increased with cooler temperatures in the fall. The proportion parous tended to increase when temperatures decreased. Estimates of adult daily survival were generally >0.8. Survival declined with temperature, was lowest in midsummer, and increased during the fall.
Alberta Animals