Meeting Abstract

47.1  Saturday, Jan. 5  When is a wasp supercool? CORRIGAN, S.T.*; IRWIN , J.; Central Wash Univ corrigas@cwu.edu

The summer biology of many temperate social Hymenoptera has been well studied, but little data are available concerning their winter physiology. To ascertain the lower limits to low temperature survival of vespid wasps, we measured the supercooling points (SCPs) of gynes from four species representing three genera of locally occurring social wasps. In all cases, a seasonal progression in cold hardening was observed; as fall advanced into winter, supercooling ability increased, resulting in progressively lower SCPs. Though data in some cases indicated differences within and between genera, we found that most local wasps in the heart of winter are able to survive at least brief exposures below -20C. Mean midwinter SCPs were as follows: ��Dolichovespula maculata��, -20.1; ��Vespula pensylvanica��, -22.3; :�Vespula germanica��, -22.6; ��Polistes dominulus��, -23.3. No wasp in our study survived freezing, even those inoculated by external ice. Our data indicate that the vespid wasps in eastern Washington State are not tolerant to freezing, and instead survive winter by the ability to supercool below temperatures that are generally experienced in hibernacula.