UC San Diego

The present work examines the thermal preference of adult Rhodnius prolixus along a temperature gradient. The mean preferred temperature differed slightly between sexes: 25.0degreesC for males versus 25.4degreesC for females. This preference was not constant, but varied daily by about 0.2degreesC for both sexes, and reached its highest value at the onset of the dark phase and was lowest during the light phase. A change in the preferred temperature with the level of starvation was also observed (about 1degreesC lower after 20 days of starvation). Changes in environmental temperature strongly affected the rate of weight loss for both sexes. When insects were maintained for 20 days in a chamber at 32degreesC, they lost significantly more weight than when kept at 24degreesC; both water loss and nutrient conversion processes are involved. This increase in weight loss rate with increasing temperature would cause a higher biting rate and consequently higher probability of Chagas' disease transmission. Females oviposit across a range of temperatures from 22 to 33degreesC with a peak at 25-26degreesC. These results are compared with patterns of thermopreference in other species of triatomine, as related to differences in their distribution and tolerance to starvation. (C) 2003 Elsevier B.V. All rights reserved.