Meeting Abstract

90.5  Monday, Jan. 6 14:30  Post-mortal CO₂ release by insects at high temperatures HEINRICH, EC*; GRAY, EM; VORHEES, AS; MEIGHER, SG; BRADLEY, TJ; Univ. of California, Irvine; Colorado College; Univ. of California, Irvine; Colorado College; Univ. of California, Irvine eheinric@uci.edu

Researchers utilizing thermolimit respirometry to study insect thermal tolerance have previously reported an unexplained surge of carbon dioxide release by insects following death at high temperatures. This phenomenon has been referred to as the “post-mortal peak” (PMP) (Lighton and Turner, 2004). In some insects, the CO₂ release rate during the PMP may be up to 50% higher than the maximal rate achieved in the live insect. We have observed the PMP in fruit flies, mosquitoes, crickets, cockroaches, and beetles. While it has been verified that the PMP occurs after death, the cause of death does play a role in the appearance of the PMP. We have observed the PMP only when an insect dies due to high temperature stress. Furthermore, the PMP does not occur in the absence of atmospheric oxygen, or if the dead insect is subjected to cyanide prior to the initiation of the peak. On the basis of these results, we hypothesize that the CO₂ released in the PMP derives from the insect’s mitochondria. We are currently simultaneously measuring CO₂ release and oxygen uptake during thermal ramping to clarify the source of the PMP. Understanding this event may provide insights into the physiological implications of heat stress in insects and the timeline of biochemical events before and after death at high temperatures.