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Adaptations of the blood-feeding insect Rhodnius prolixus to a life that sucks.

October 8, 2015

Dr. Juan A. Ianowski Department of Physiology University of Saskatchewan

Thursday, October 8, 2015 at 11:45 a.m. Rm. 125, W.P. Thompson (Biology) Building

ABSTRACT: R. prolixus is an insect vector of Chagas' disease, a condition endemic in South and Central America that takes thousands of lives each year. This insect feeds on the blood of mammals, birds, and there have been reports of predation on amphibians. In each meal the insect ingests up to 15 times its own body weight in host blood. These massive meals expose R. prolixus to increased risk of predation due to the reduced mobility of the insect, osmotic stress as a result of the difference in the osmotic pressure of the host blood and the insect's haemolymph, and thermal stress from the host's warm blood. In this presentation I will discuss the adaptations R. prolixus has evolved to survive osmotic and thermal stress during blood meals. I will discuss the mechanism that allow R. prolixus to excrete the excess water, sodium and chloride ingested with each meal. Our data shows that the renal system of R. prolixus is regulated by hormones as well as mechanism intrinsic to the Malpighian (renal) tubules. As a result the tubules are capable of producing massive volumes of urine that allows this insect to excrete 50% of the blood meal (the plasma fraction of the blood) within 2 hours. I will also discuss the adaptations that allow these insects to deal with the heat loaded during each meal. Our research indicates that this insect is able to thermoregulate during a blood meal. Thus, only the head of the animal warms up during a blood meal while the thorax and abdomen are kept much cooler.