RESPONSES OF TSETSE-FLIES (DIPTERA, GLOSSINIDAE) TO WARTHOG (PHACOCHOERUS-AETHIOPICUS PALLAS)

In Zimbabwe, living and stuffed warthogs (Phacochoerus aethiopicus Pal las) were placed within an incomplete ring of electric nets and observ ations were made of the numbers of Glossina pallidipes Austen and G. m orsitans morsitans Westwood attracted to the hogs, the alighting posit ion and feeding responses of tsetse, and the grooming behaviour of the warthogs. Between 26 and 31% of tsetse landed on the head region of a n adult live warthog compared to 8% for a juvenile and 4% for a stuffe d warthog. The number of tsetse alighting adjacent to the eye of a stu ffed warthog increased 20 times if dark patches were fixed there. The percentage of tsetse alighting on the head region of the adult warthog increased from 25% to 50% as the number of tsetse caught on the ring of nets increased from < 100 to > 800. There was a concurrent increase in the rate of skin twitches and ear flicks by the warthog. For an ad ult warthog, 26% of tsetse leaving the vicinity had fed compared to on ly 1% for a juvenile. It is suggested that the concentration of tsetse on the head of adult warthogs is a visual response to the dark patch produced by the pre-orbital glands of a mature warthog and to density- dependent changes in the grooming responses of warthogs.