One cause or consequence of life’s “fondness” for insects is the fact that this class is represented in habitats ranging in temperature from sub-zero to dry desert extremes. Insects exhibit the highest heat tolerance among land animals; among insects the ant is currently claimed as the “most thermo-tolerant” by Wehner, Marsh and others in studies of African and Australian species. Although our understanding of heat shock and stressor-activated protein biology increases exponentially, the physio/biochemical mechanisms for for such remarkable thermal capacities remain an area ripe for discovery. Insects open an opportunity for whole-organism research often obstructed for other animals. The fast-paced, yet open-ended field demands persistent inquiry, evaluation and re-evaluation. By way of example, our in-situ study of the Namibian Myrmecine, Ocymyrmex sp. revealed a CT max of 55°C, equaling or surpassing the thermal record noted for the Saharan species Cataglyphis bombycina, and the claims of its Australian Formicine cousin, Melophorus spp. In addition, survival time at 55°C is significantly increased by prior exposure to high temperatures. The distinct caveat to our claim is that the methodology used in the three studies differed. Immediate thermal “immersion” contrasts with progressive temperature ramping; both contrast with observational data at a single temperature. Different methods may induce and/or incorporate a different biochemical history and thus elicit variation in results. Using a Sable Systems temperature-controlled TR-2 Respirometry system wehave extended our study to compare these varying methods in the Mojave desert ant, Pogonomyrmex rugosus. The implications of different rates of temperature are evaluated in the light of metabolic response of the ant. While standardization of methods is desirable as the field of thermal biology defines itself, by contrasting and combining physiological methods one may derive useful biochemical and ecological questions which can be explored with greater rigor.
Species 1: Hymenoptera Formicidae Ocymyrmex nr. fortier
Species 2: Hymenoptera Formicidae Pogonomyrmex rugosus (harvester ant)
Keywords: Thermo-tolerance
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA