Odour-mediated host preference of Culex quinquefasciatus in Tanzania

Field experiments to determine the host preference of Culex quinquefasciatu s Say (Diptera: Culicidae) between man, calf and goat, were conducted in Mu heza, north-east Tanzania. The responses of the mosquito to the three hosts were also compared to their responses to carbon dioxide. A total of 2565 u nfed female mosquitoes were collected, of which Cx quinquefasciatus account ed for 96.6% of the catch. A human-baited tent caught a larger number of ho st-seeking Cx quinquefasciatus than a calf-baited or goat-baited tent (P < 0.05). The man:calf ratio was 7.8:1 while the man:goat ratio was 10:1. The difference in response to either a calf- or goat-baited tent was not statis tically significant (P > 0.05). The number of mosquitoes attracted to a hum an-baited tent was significantly larger than that attracted to carbon dioxi de released at 300 ml min(-1). Only 25.3% of the human host attractancy was attributed to carbon dioxide. The number of Cx quinquefasciatus responding to a tent baited with a calf or goat was not significantly different from the number responding to a tent baited with carbon dioxide. It can be concl uded that with equal availability of the three vertebrate hosts, Cx quinque fasciatus would respond more to volatile cues from a human host than from e ither a calf or goat, thereby supporting earlier data about its high degree of anthropophily. The major olfactory cue from a goat or a calf to which t his mosquito responds is probably carbon dioxide.