Meeting Abstract

52.5  Thursday, Jan. 6  Warming up and cooling down after a very large hot drink by blood-sucking bugs (Rhodnius prolixus) LOUDON, C.*; BRADLEY, T.J.; Univ. of California, Irvine; Univ. of California, Irvine cloudon@uci.edu

As small ectotherms, insects are subject to rapid changes in body temperature following changes in their thermal environment. Blood-sucking bugs of the species Rhodnius prolixus are among the largest of blood-feeding arthropods that feed on humans. In a matter of minutes, Rhodnius can ingest up to ten times their body mass in hot blood. We used an FLIR thermal camera to measure the surface temperature of individual bugs (nymphs and adults). We found that the surface temperature of the bugs increased to an average of 32.1 C during feeding (measured using an FLIR thermal camera, in room temperature of 22 C). In order to evaluate the thermal insulation of the bugs, we compared their rates of cooling after heating internally (with a blood meal) or externally (in a warm glass enclosure). During cooling, the surface temperature of the bugs declined at a similar rate regardless of the heating source, suggesting that the bugs are poorly insulated internally, and that the controlling temperature gradient is between the bug and its environment (that is, the dimensionless Biot modulus, Bi, is small). Measurements of walking speed in warm vs. room temperature bugs (warmed at 38 vs. 22 C) showed an increase by least a factor of 2 in walking speed. This suggests that the elevation in body temperature associated with blood feeding is brief but may be important in enhancing the speed with which the fed bug can move away from its host. Thanks to Dr. Brian Helmuth (U. of South Carolina) for the loan of a thermal camera for this project.