Meeting Abstract

P3.59  Monday, Jan. 6 15:30  Plasticity of pigmentation and thermoregulation of the harlequin bug, Murgantia histrionica, in response to developmental temperature WHITE, A E*; OLSON, J R; Kenyon College; Kenyon College whiteae@kenyon.edu

Sustaining homeostasis in a changing environment relies on an organism’s ability to maintain an internal temperature within a specific range through thermoregulation. When temperatures fall outside an optimal range, metabolic, reproductive and behavioral functions can be impaired. As poikilothermic ectotherms, insects must rely on mechanisms other than metabolic heat production to protect themselves from extreme temperatures. Many insects, such as the harlequin bug (Murgantia histrionica), demonstrate phenotypic plasticity in body color, possibly taking advantage of solar radiation to warm and cool their bodies. On its dorsal side, the harlequin bug displays geometric patterns resulting from a juxtaposition of black and either yellow, red, or orange, and this ratio of black to color can have substantial variation among individuals. In order to investigate the impact of temperature on pigmentation patterns, we reared harlequin nymphs in two thermal environments, mimicking the seasonal temperatures observed in their natural geographic range. We then quantified the black to color ratio using digital imagery. As predicted, adult phenotype varied between treatments. In order to assess thermoregulation capabilities of each phenotype, we also monitored the temperature of adult harlequin bugs in dark and basking conditions, both before and after altering their pigmentation. Our results showed that individuals with a darker pigmentation were able to raise their body temperature to greater extent. These results suggest that colder temperatures experienced late in the season may induce the development of a darker phenotype, potentially improving the insect’s immediate and over-winter survival.