Development of Immature Culicoides variipennis (Diptera: Ceratopogonidae) from Saltville, Virginia, at Constant Laboratory Temperatures

Abstract

Immature stages of Culicoides variipennis (Coquillett) from southwestern Va. were reared in natural substrate using constant photoperiod (14:10 [L:D]) and temperatures (20, 23, 27, 30, and 35°C). Developmental threshold temperatures (°C) and thermal constants were 7.5°C and 495.4 degree-days (DD) for larvae and 11.7°C and 31.0 DD for pupae. Egg development was too variable for calculation of meaningful threshold values. Developmental threshold values (<1.3°C) were similar to values previously published for New York populations of C. variipennis. The overall rate of development in the larval stage was significantly slower for Virginia midge populations than for New York populations. The data suggested that nutritional stress affected duration of larval development. In general, adult midges reared at lower temperatures were larger than those reared at higher temperatures. At a given temperature, females were significantly larger than males, but we observed no significant differences in larval or pupal duration between males and females.