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Mosquito responses to carbon dioxide in B West African Sudan savanna village
Author(s) -
COSTANTINI CARLO,
GIBSON GABRIELLA,
SAG N' FALÉ,
TORRE ALESSANDRA DELLA,
BRADY JOHN,
COLUZZI MARIO
Publication year - 1996
Publication title -
medical and veterinary entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 82
eISSN - 1365-2915
pISSN - 0269-283X
DOI - 10.1111/j.1365-2915.1996.tb00734.x
Subject(s) - anopheles gambiae , biology , mansonia , culex , culex quinquefasciatus , veterinary medicine , sibling species , ecology , toxicology , malaria , larva , medicine , aedes aegypti , immunology
. Mosquito responses to carbon dioxide were investigated in Noungou village, 30 km northeast of Ouagadougou in the Sudan savanna belt of Burkina Faso, West Africa. Species of primary interest were the main malaria vectors Anopheles gambiae S.S. and An.arabiensis, sibling species belonging to the An.gambiae complex. Data forAn.finestus, An.pharoensis, Culex quinquefasciatus and Mansonia uniformis were also analysed. Carbon dioxide was used at concentrations of 0.04‐0.6% (cf. 0.03% ambient concentration) for attracting mosquitoes to odour‐baited entry traps (OBETs). The ‘attractiveness’ of whole human odour was also compared with CO 2 , emitted at a rate equivalent to that released by the human bait. In a direct choice test with two OBETs placed side‐by‐side, the number of An.gambiae s. I. entering the trap with human odour was double the number trapped with CO 2 , alone (at the human equivalent rate), but there was no significant difference between OBETs for the other species of mosquitoes. When OBETs were positioned 20 m apart, again CO 2 , alone attracted half as many An.gambiae s.l. and only 40% Anlfunestus, 65% Ma.uniformis but twice as many An.pharoensis compared to the number trapped with human odour. The dose‐response for all mosquito species was essentially similar: a linear increase in catch with increasing dose on a log‐log scale. The slopes of the dose‐response curves were not significantly different between species, although there were significant differences in the relative numbers caught. If the dose‐response data are considered in relation to a standard human bait collection (HBC), however, the behaviour of each species was quite different. At one extreme, even the highest dose of CO 2 , did not catch more An.gambiae s.1. than one HBC. At the other extreme, the three highest doses of CO 2 , caught significantly more Ma.unifonnis than did one HBC. An.pharoensis and Cx quinquefasciatus showed a threshold response to CO 2 , responding only at doses above that normally released by one man. An.funestus did not respond to CO 2 , alone at any dose in sufficient numbers to assess the dose response. Within the An.gambiae complex, An.arabiensis 'chose' the CO 2 ,‐baited trap with a higher probability than An.gambiae S.S. Also An.arabiensis, the less anthropophilic of the two species, was more abundant in CO 2 ,‐baited OBETs than in human bait collections.