Patterns of fructose feeding by Culex tarsalis (Diptera: Culicidae).

Abstract

Culex tarsalis collected in Kern County, California, USA, were tested for the presence of fructose from July 1984 through February 1985 using the cold anthrone reaction. Overall, 75% of 350 females and 68% of 251 males collected during summer (July–September) were fructose positive. Host-seeking females ingested fructose during the 2nd half of the night. Fructose was ingested repeatedly throughout life, since empty, blood-fed, gravid, and parous females exhibited comparable percentages of fructose positivity. Males ingested fructose at night after swarming at dusk. Females ingested fructose when entering diapause (62% of 69 females in October–November), diapausing (42% of 175 females in December–January), and terminating diapause (78% of 75 females in February). Overwintering female populations consisted of mobile and sedentary components. The mobile component, which rested in more exposed microhabitats such as privies, bridges, and red boxes, frequently ingested fructose and included some females that were not diapausing. The sedentary component, which generally rested in more protected hibernacula such as rodent burrows, brush piles, and Neotoma nests, infrequently ingested fructose and consisted mostly of diapausing females. During diapause termination, the sedentary component initiated ovarian development, egressed from hibernacula, ingested fructose, and rested in more exposed microhabitats, thereby increasing female abundance at exposed resting sites.