Some aspects of the behaviour,ecology and vectorial capacity of glossina brevipalpis newstead and other flies in the Luangwa valley of Zambia
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Studies were carried out in the South Luangwa National Park, located in the Luangwa Valley Zambia., on the behaviour, ecology and vectorial capacity of G. brevipalpis and G. m. morsitans and G. pallidipes. The catch of G. brevipalpis was low in odour baited epsilon, NGU2G, F3 and biconical traps throughout the year. It was, however, observed that the flies were attracted to the traps but did not enter. Glossina brevipalpis was not easy to catch with ordinary fly rounds, but with the use of an electric screen fly round, more of this fly were caught. The best sampling system for G. brevipalpis was found to be artificial refuges which worked better in the hot dry season from mid-August to mid-December. Tsetse flies started entering refuges from 09:00 h and left after 16:00 h and this is the time in which tsetse flies rest because the environmental conditions negate tsetse fly survival during this period. Refuges with a total volume of at least 200 liters were more efficient for as long as they were dark, insulated and provided with shade. Glossina m. morsitans was caught more on fly rounds than using traps while, G. pallidipes was captured more with traps than in any other sampling system used. Like G. brevipalpis, both G. m. morsitans and G. pallidipes responded well to artificial refuges. Glossina brevipalpis was concentrated in the riverine vegetation type throughout the year while G. m. morsitans and G. pallidipes were more concentrated in the mopane and thicket vegetations. Glossina brevipalpis was also observed to be a very localised fly to the riverine vegetation and rarely leaves it. Using a circular setting of seven artificial refuges of 300 m radius to the one centrally placed gave a recapture rate of 7% over a period exceeding three weeks. It was noted that even in such a small area used some refuges outside the riverine vegetation but within the said radius did not capture any G. brevipalpis. Although the catches for artificial refuges and* traps were different in terms of species composition, the age distribution by both ovarian and wing fray analysis were similar. There was also*no significant differences in infection rates of G. brevipalpis (3.3%), G. pallidipes (3.5%) and G. m. morsitans (4.4%). Species identification of trypanosomes were investigated for G. brevipalpis using a protocol which was developed specifically to isolate trypanosome DNA in tsetse fly parts for amplification by the PCR technique. The technique was able to identify 100% of the T. congolense (Savannah) and 43% of the f. congolense-like infections in tsetse fly midguts were identified to be T. brucei. Trypanosoma vivax and T. simiae primers did not amplify and reasons for this are suggested. Glossina brevipalpis was therefore, shown to be a potential vector of African trypanosomosis and hence further studies on the ecology and control of this species are recommended.
- Veterinary Medicine