a1 Overseas Development Natural Resources Institute, Central Avenue, Chatham Maritime, Chatham, Kent, ME4 4TB, UK
a2 O.D.A. Tsetse Transition Phase, c/o British Embassy, P.O. Box 1036, Mogadishu, Somalia
Studies were carried out at Jilaal Moogi, south-eastern Somalia, of the responses of Glossina pallidipes Austen to traps and targets. F3 traps caught three times as many tsetse as a biconical trap. Baiting F3 traps with acetone (released at 5–50 000 mg/h), butanone (10–50 mg/h) or octenol (0·05–5 mg/h) either alone or as mixtures did not affect the catch significantly. The catch was increased by 1·6 times (P<0·05) by releasing a mixture of 4–methylphenol (at 0–2 mg/h) and 3-n-propylphenol (0·04 mg/h), and by four times by releasing a mixture of acetone (500 mg/h), octenol (0·5 mg/h) and the two phenols. Baiting a target enclosed in an electric net with the combination of acetone, octenol and phenols increased the catch only 1·3 times, (P>0.05). Baiting an electric net plus target with natural ox odour increased the catch 1·8 times (P<0·05). A pthalogen blue (peak reflectivity = 40% at 450 nm) target caught 1·7 times as many tsetse as a black target (P<0·01) and a standard blue (reflectivity = 29%) target caught 7·4 times the catch of a yellow one (P<0·001). The results are compared with published data from Zimbabwe, Kenya and Mozambique, and it is noted that the level of response of G. pallidipes in Somalia to host odours is lower than elsewhere.
(Received June 21 1988)