MOSQUITOES (DIPTERA:CULICIDAE) IN IRRIGATED AREAS OF SOUTHERN ALBERTA AND THEIR SEASONAL CHANGES IN ABUNDANCE AND DISTRIBUTION

Abstract

More than 95% of the mosquitoes in southern Alberta develop in waste irrigation water. Sixteen species of four genera in the subfamily Culicinae were identified, namely, Anopheles earlei, Culex tarsalis, Culiseta inornata, Culiseta alaskaensis, Aedes vexans, A. cinereus, A. dorsalis, A. campestris, A. spencerii, A. flavescens, A. nigromaculis, A. riparius, A. sticticus, A. intrudens, A. cataphylla, A. melanimon; and two species in the subfamily Chaoborinae, namely, Chaoborus americanus and C. flavicans. Weekly index of the number of larvae and pupae as the average number per dip multiplied by the area in square yards, and total weekly trap catches of adults of the seven most common species were computed for each of three irrigation districts, representing distinctly different farming practices. Adults were more numerous in a sheltered than in an open site, the males noticeably more so than the females. Mosquitoes were more abundant in the older than in the newer irrigated districts, and improper farming and water-management practices favored increase in numbers, even in well-planned irrigation districts.