Meeting Abstract

P2.127  Monday, Jan. 5  Diapause regulation in Pyrrharctia isabella REED, BR; BENNETT, VA*; Clarion University, Pennsylvania; Clarion University, Pennsylvania

When trying to survive stressful environmental conditions, insects can enter one of two types of dormancy: quiescence or diapause. Quiescence is a direct response to current conditions and is easily reversible when conditions revert to normal. In contrast, diapause occurs in anticipation of unfavorable seasonal conditions and is characterized by a period of insensitivity to current conditions. Metabolic depression is an indicator of diapause. Pyrrharctia isabella overwinters as the banded woolly bear caterpillar. Previous studies found that P. isabella in northern populations enter diapause. However it was suggested that there may be latitudinal population differences in the type of dormancy P. isabella enters. We examined a Pennsylvania population of P. isabella larvae. We exposed fall and winter field acclimatized larvae to summer temperatures and photoperiod, and measured changes in metabolic rates and development. Although metabolic data were inconclusive, winter collected larvae continued development while fall collected larvae did not, thus indicating that this population enters diapause and not quiescence. Our current objective is to repeat metabolic measurements and determine how long this Pennsylvania population of P. isabella larvae remain in refractory phase of diapause and when diapuse is terminated. We will expose field acclimatized larvae from early October through late December to summer temperature and photoperiod periodically throughout the fall and winter. We will record changes in metabolic rates and continuation of development. We will also measure seasonal changes in supercooling points and glycerol production as indicators of freeze-tolerance. Data are forthcoming.