Response of tsetse flies to trypanosome-induced odors

Project Summary The tsetse fly transmits trypanosomiasis to humans and animals across 38 countries of Africa. In humans the disease is called African Sleeping Sickness. There is no vaccine to prevent it, and 70 million people are at risk. In animals the disease is called nagana, and it imposes a major economic burden on sub- Saharan Africa. The most effective means of preventing these diseases has been to control the tsetse flies that spread them, and olfactory traps have been particularly useful. Tsetse flies find their human and animal hosts largely through olfactory cues. The flies also depend on olfaction to avoid predators, find mates, and identify sites on which to deposit their offspring. Better understanding of the tsetse olfactory system may lead to better means of control. Parasites use a rich variety of strategies to increase their reproductive success through manipulation of their vectors and hosts. We have recently discovered that infection with trypanosomes leads to the production of 21 volatile compounds in tsetse. This proposal tests hypotheses about the neuronal, receptor, and behavioral responses of tsetse flies to these volatile compounds. The first aim investigates the electrophysiological response of tsetse antennal neurons to trypanosome-induced odorants. This analysis will determine which individual chemical compounds are most effective at low concentrations. These compounds may be useful in controlling tsetse and other insect vectors of mammalian diseases. The second aim measures the response of tsetse odorant receptors to trypanosome-induced odors, taking advantage of an in vivo expression system in Drosophila. The third aim tests hypotheses about behavioral responses to trypanosome- induced odors using a two-port olfactometer. It will also test the impact of trypanosome-induced odors on mating behavior. The proposal should provide new insights into one of the most important themes in vector biology: the biological interactions between the parasites that cause disease and their vectors. The experimental plan is designed to test hypotheses about the trypanosome-induced odors and the responses of tsetse flies to them. The study may also identify odorants that are useful in controlling tsetse in the field and thereby reducing the incidence of the diseases that they spread. The proposal will provide training in electrophysiology and molecular biology to Dr. Shimaa Ebrahim, who has little experience in these topics. The project will benefit from an environment that contains a great deal of expertise in insect olfaction. The study takes unique advantage of resources at Yale, which is one of the world's centers of tsetse research.