Larval behavior of four Culex (Diptera: Culicidae) associated with treatment wetlands in the southwestern United States.

The diving behavior, aggregation, horizontal distribution under two food regimes, and response to change in ambient light level were studied for fourth instars of four Culex species in the laboratory. Under low food conditions, Cx. erythrothorax larvae dived less frequently, exhibited greater aggregation, and had stronger preferences for the corners of the observation chamber than did larvae of three congeners (Cx. tarsalis, Cx. quinquefasciatus, and Cx. stigmatosoma). Under high food conditions, larvae of all species were more sedentary than under low food conditions; however, the behavior of Cx. erythrothorax larvae changed comparatively little with changes in food abundance. Culex erythrothorax was the most responsive to disturbance (an 11% change in ambient light level), whereas Cx. tarsalis larvae did not respond to small changes in ambient light level. The behavior of Cx. erythrothorax larvae differed significantly from the three congeners studied. Species-specific behavioral differences of larvae may have contributed to the discrepancies of species relative abundance in larval surveys versus emerging adult mosquito collections at constructed wetlands noted in previous studies.