Field studies of the response of tsetse flies (Glossindae) and other Diptera to carbon dioxide, acetone and other chemicals

In studies in the Zambesi Valley, Zimbabwe, carbon dioxide alone dispensed at 2.5 to 15 litres/min, or acetone alone dispensed at 0.3 to 300 g/h, increased by up to 6 times the catches of Glossina morsitans morsitans Westw. and G. pallidipes Aust. from stationary biconical traps, stationary electrocuting traps used with and without a visual target, and a mobile party of hand-net catchers. Catches were increased further when the chemicals were dispensed together. Carbon dioxide at 2.5 litres/min plus acetone at 15 g/h was about half as effective as ox odour for enhancing the catches from an electrocuting trap plus target; the efficacy of carbon dioxide at 15 litres/min plus acetone at 300 g/h was not significantly different from that of ox odour. Several short-chain ketones, and also formaldehyde and propionaldehyde, were attractive. Several long-chain ketones, and also heptaldehyde and caproic acid, were repellent. Carbon dioxide was attractive for Tabanidae, Stomoxyinae and non-biting Muscidae. Acetic acid was repellent for Stomoxyinae and non-biting Muscidae.