SPECIES VARIATION IN THE RESPONSE OF TSETSE-FLIES (GLOSSINA SPP DIPTERA, GLOSSINIDAE) TO PARTURITION HORMONE

Parturition hormone, present in the uterus of several species of Gloss ina, causes expulsion of the uterine content in neck-ligated, pregnant females of Glossina morsitans, thus eliciting either parturition or a bortion. Uteri of all six tsetse species tested (G. morsitans, G. aust eni, G. brevipalpis, G. palpalis, G. fuscipes, G. pallidipes) contain parturition hormone activity, and neck-ligated females of G. morsitans , G. austeni, G. palpalis and G. pallidipes all respond to the hormone by giving birth. Though uterine extracts of both G. brevipalpis and G . fuscipes also contain parturition hormone activity, females of these species fail to respond to a hormone injection in our assay system. T his suggests that additional or alternative regulatory mechanisms are involved in regulating parturition in certain species.