Cattle-tsetse contact in relation to the daily activity patterns of Glossina morsitans submorsitans in The Gambia.
The daily flight activity patterns of one of the main vectors of animal trypanosomiasis in West Africa, Glossina morsitans submorsitans, were assessed using four different methods. Results from all the methods showed that there was some flight activity nearly every hour in all seasons but they differed in the level of contact between grazing cattle herds and G.m.submorsitans. In the late dry season, trap data indicated that there was negligible activity from midday to late afternoon, whereas observations of tsetse contact with cattle herds or hand-net collections on herd followings showed no fall in attack rates, on the cattle by G.m.submorsitans. Differences between trap and animal-baited collection data may be attributable to the type of G.m.submorsitans sampled by each method. Male G.m.submorsitans captured by traps were more fat depleted than those caught on ox-baited flyrounds or by hand-net collections on herd followings. All methods showed that male G.m.submorsitans were most fat depleted in the late dry season and least in the early dry season. It was concluded that the traps were mainly sampling the spontaneous flights of G.m.submorsitans. Hunger and endogenous rhythms increase the likelihood of spontaneous flights towards dusk, particularly in conditions such as those at midday in the very hot, late dry season. However, the presence of cattle herds in infested habitats probably activated nearby G.m.submorsitans and the continual movement through the grazing areas ensured contact with tsetse throughout grazing.(ABSTRACT TRUNCATED AT 250 WORDS)
Rawlings
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International Trypanotolerance Centre, Banjul, The Gambia.
Wacher
T J
TJ
Snow
W F
WF
D000818:Animals; D002417:Cattle / Q000469:parasitology*; D002980:Climate; D005714:Gambia; D007300:Insect Control / Q000379:methods*; D007303:Insect Vectors; D008297:Male; D014370:Tsetse Flies / Q000502:physiology*