Attractiveness of black rhinoceros (Diceros bicornis) to tsetse flies (Glossina spp.) (Diptera: Glossinidae) and other biting flies

During translocations of black rhinoceros (Diceros bicornis Linnaeus) in Kenya, we studied the relationships between the rhinoceros and biting flies. In trapping experiments, rhinoceros waste products (urine or dung) were substituted for known attractants such as cow urine, l-octen-3-ol or acetone. Catches of Glossina pallidipes Austen, Glossina longipennis Corti, Stomoxys spp., and Haematopota spp. were not affected by these substitutions. NG2G and Vavoua traps sited near captive animals caught similar numbers and kinds of flies as traps set without animals. Any minor attractive properties of rhinoceros odours were probably due to the presence of known attractants such as 4-cresol and 3-n-propylphenol, which were confirmed to be present through gas chromatography—mass spectroscopy. In feeding trials with laboratory-reared tsetse, Glossina brevipalpis Newstead and Glossina morsitans centralis Machado fed well on immobilized animals, whereas G. longipennis fed reluctantly. Catches of G. brevipalpis were doubled in one trapping experiment when rhinoceros urine was used as odour bait. Philoliche spp., Haematopota spp. and other Tabanidae fed on captive rhinoceroses. Many species of Stomoxyinae were associated with rhinoceroses. Of these, the most frequent association was with Rhinomusca dutoiti Zumpt, a species found previously only in South Africa. Rhinomusca dutoiti was found in two highland rhinoceros sanctuaries, Nairobi National Park and Solio Ranch Game Reserve.

Traps and odour baits for the tsetse fly, Glossina longipennis (Diptera: Glossinidae)

Studies were carried out at Nguruman, south-west Kenya to develop an effective trap/odour bait system that could be used for sampling and possibly controlling the tsetse Glossina longipennis Corti. Neither acetone nor cow urine increased trap catches significantly when used alone, but together they increased catches by about four to five times. Used with a target and electric screens, acetone with p-cresol, 3-n-propyl phenol and 1-octen-3-ol gave a significantly higher index of increase than did acetone and cow urine. The use of odour baits did not affect the age composition of the catch. The standard F3 trap was about three and a half times more effective for females than was the biconical trap and about eight times more effective when used without its blue floor. The NG2B was the best of the NGU series of designs, and caught about four times more females than did the biconical trap. Neither the F3 nor the NG2B caught significantly more males than the biconical trap. The NG2B caught a significantly higher proportion of parous female flies than the biconical. Either the F3 or the cheaper NG2B, baited with acetone and cow urine or phenols, is recommended as a sampling tool for G. longipennis. Electric screen experiments showed that the NG2B caught less than 10% of the flies that approached it. Despite this, it might still be effective for control of G. longipennis given the high mobility of this species and the consequent likelihood of encountering traps.