REGULATION OF METAMORPHOSIS BEHAVIOR IN THE TSETSE FLY

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This proposal will enable the investigators to participate with scientists in Kenya on a research program aimed at the discovery of neuroendocrine mechanisms that serve to coordinate metamorphic behavior in tsetse, the vector of African trypanosomiasis. Tsetse has a peculiar reproductive strategy in which larval development is completed within the uterus of the female and she gives birth to a fully developed third instar larva. Using techniques of larval ligation, ecdysteroid injection, and ecdysteroid RIA's, the time of commitment to metamorphosis and the timing and critical release of the ecdysteroids that trigger pupariation will be determined. The female's contribution to parturition will be monitored with a barographic technique to record changes in hemolymph pressure and by in vitro preparations of uterine muscles: both techniques will be used to assay the efficacy of hormones and other agents in eliciting the parturition response. The barographic technique will also be used to quantify the dramatic changes in hemolymph pressure that normally occur during pupariation. Alterations of the hemolymph pressure profile and responses to Sarcophaga pupariation bioassays will be used to test for the presence of discrete hormones that regulate subsets of pupariation: larval immobilization, retraction of the anterior segments, longitudinal contraction, and tanning. The mechanisms of pupation and pupal head evagination will also be measured barographically, and exogenous ecdysteroids will be tested for their efficacy in blocking this process. Eclosion and post-eclosion behavior (escape from the puparium, digging, and imaginal expansion) will be described with barographic and tensometric methods, and the hormonal regulation of these various behaviors will be investigated using bioassay techniques previously developed in Sarcophaga. This study should provide a basis for understanding metamorphic behavior and its neurohormonal regulation in tsetse and may thus augment strategies for the control of this important pest species.