Improved survival of laboratory-reared tsetse flies Glossina morsitans morsitans (Diptera: Glossinidae) through use of homidium bromide-treated blood diet

Homidium bromide is a broad-spectrum anti-microbial trypanocide likely to be encountered as a violative residue in blood collected from abattoirs destined for feeding laboratory-reared tsetse colonies. We investigated its effects on longevity of laboratoryreared Glossina morsitans morsitans Westwood. Four steers were intra-muscularly administered with 1 mg homidium bromide/kg of body weight and blood was aseptically collected from them between 15 and 30 min post-administration. This blood was defibrinated, analysed for homidium levels, screened for bacterial contamination, frozen and warmed to 37°C before feeding to tsetse flies. Teneral male (100) and female (220) G. m. morsitans flies were fed on homidium-treated diet, and control flies (99 males and 187 females) on untreated blood diet and their survival monitored for 163 days. Homidium, at 266.15 ng/ml blood diet, significantly (P < 0.05) improved fly survival. We concluded that homidium bromide has a beneficial effect on tsetse, probably attributable to its antimicrobial activity against unfavourable microbes mediated by the drug, and could be used as a tsetse diet additive.