A FIELD TRIAL OF PYRIPROXYFEN-TREATED TARGETS AS AN ALTERNATIVE METHOD FOR CONTROLLING TSETSE (DIPTERA, GLOSSINIDAE)

A juvenile hormone mimic (pyriproxyfen) was used with odour-baited tar gets to assess its suitability for controlling tsetse flies (Glossina spp.). In August 1991, 41 odour-baited targets identical to those used with insecticide in tsetse control operations, were each treated with 4 g of pyriproxyfen and deployed near Rekomitjie Research Station, Za mbezi Valley, Zimbabwe, in a 12.3 km2 block of woodland habitat of Glo ssina morsitans morsitans Westwood and G. pallidipes Austen. After thr ee months, emergence rates from puparia of the two species collected i n the block fell to 34% and 20% of control levels; 50 and 70%, respect ively, of puparia of the two species collected were found, on dissecti on, to show arrested development. Changes in mean ovarian age and wing -fray category in the tsetse population during the trial were due part ially to the pyriproxyfen and partially to high mortality, in the larv al/pupal stages and in young adult flies, which occurs each year in th e hot/dry season. Chemical analysis of cloth samples indicated that af ter four months 68-85% of the pyriproxyfen had been lost, a large prop ortion apparently dripping off the bottom of the target. If the techni cal problem of persistence can be solved pyriproxyfen could substitute for pesticides in target-based tsetse control operations.