Bionomics of Anopheles quadrimaculatus and Culex erraticus (Diptera: Culicidae) in the Falls Lake basin, North Carolina: seasonal changes in abundance and gonotrophic status, and host-feeding patterns

Abstract

Larval and adult Anopheles quadrimaculatus Say (sensu lato) and Culex erraticus (Dyar & Knab) were collected at Falls of the Neuse Lake (Falls Lake) in North Carolina from May 1985 to December 1986. Adult mosquitoes were aspirated weekly from shelters in woodlands adjacent to larval sampling sites. An. quadrimaculatus and Cx. erraticus comprised > 95% of the total number of mosquitoes collected. An. quadrimaculatus adults exhibited vernal and autumnal peaks of abundance during both years. Cx. erraticus adults exhibited several peaks of abundance in summer and early fall of both years. An. quadrimaculatus initiated blood feeding in May and April 1985 and 1986, respectively. Only unfed females were found in late fall and winter. Cx. erraticus initiated blood feeding earlier than An. quadrimaculatus. In 1985, approximately 25% of the females in the first collection in May contained a blood meal, whereas in 1986, approximately 10% of the females in the first collection in April were blood fed. Females of both species ceased blood feeding in late fall. Larvae were sampled on a weekly basis from lake edge, flood plain, and creek edge habitats. Generally, An. quadrimaculatus larvae were most abundant in lake edge and flood plain habitats, whereas Cx. erraticus larvae were most abundant in the creek edge habitat. The population dynamics of An. quadrimaculatus were associated with seasonal changes in the level of Falls Lake. In 1985 and 1986, the level of Falls Lake gradually declined from May to mid-August until heavy rainfall caused a 1-m rise in lake level. Populations of An. quadrimaculatus larvae and adults increased significantly following the rise in the level of Falls Lake. In contrast, the abundance of larval and adult Cx. erraticus decreased with rising lake levels in late August. Water level management should be an effective method for controlling populations of An. quadrimaculatus but not for Cx. erraticus. Blood-fed mosquitoes were tested to identify bloodmeal hosts using both capillary precipitin and enzyme-linked immunosorbent assays. An. quadrimaculatus (n = 941) predominantly (99%) fed on mammals, principally white-tailed deer and horses. Cx. erraticus (n = 348) exhibited an opportunistic host-feeding pattern; blood meals were taken from mammalian (49%), reptile or amphibian (20%), and avian (31%) hosts.