Preliminary observations on Tabanidae at a tsetse picket in the Republic of Zambia

In Zambia there are tsetse pickets consisting of manned wooden or metal gates or concrete or wooden enclosures, through which vehicles and pedestrians are channelled, and insecticides are applied to the vehicles for the control of Glossina spp. carried on them and drivers, cyclists and pedestrians are also treated. In view of the growing concern about the role of tabanids in the mechanical transmission of cattle trypanosomiasis, a suggestion of monitoring numbers of these carried on vehicles through tsetse pickets was followed up in November 1975-April 1976. Sticky traps on fallen trees, bushes, tops of standing trees, wooden gates and fence posts were used to trap tabanids at various distances from one such picket located at the edge of miombo woodland infested by both Glossina and tabanids, and the species-composition and settling behaviour of tabanids were studied. Tabanus coniformis Ric., T. taeniola P. de B., Haematopota distincta Ric., H. stimulans Aust., H. perturbans Edw., H. decora Wlk. and T. sandersoni Aust. were collected from vehicles and traps at the picket, but H. pallidimarginata Aust and H. hirsutitarsis Aust. were not collected, although they were found in the adjacent woodland during the study period. The variable numbers of tabanids at various distances from the spraying point were not significant; substantial numbers were found at 30 m from the spraying point. Most tabanids were trapped on tree tops and fewest on fallen trees. The total number caught near the picket was almost equal to the number caught from vehicles. H. distincta and H. decora followed vehicles after they had left the picket.