Emergence patterns of Culex mosquitoes at an experimental constructed treatment wetland in southern California.

The emergence patterns of mosquitoes inhabiting a 0.1-ha experimental wetland in southern California were monitored using emergence traps during the late summer and autumn of 1996. Culex erythrothorax was the largest contributor to emerging populations, comprising 94% of the total emerged adults with an average emergence rate of 59 adults/day/m2. None of the Culex species exhibited a pattern of emergence associated with water depth (range: 5-60 cm). Culex quinquefasciatus and Cx. tarsalis did not show a pattern of emergence associated with the inflow-outflow gradient; however, Cx. erythrothorax emerged in higher numbers along a transect at the middle of the wetland than from near the inflow and outflow. Additionally, the number of emerged Cx. erythrothorax was positively correlated with the density of vegetation below emergence traps. The comparatively large number of adults emerging from the middle of the wetland was most likely caused by a trade-off between an increasing gradient of resource abundance and a decreasing gradient of toxic compounds from the inflow to the outflow of the small wetland.