USDA-ARS Red River Valley Agricultural Research Center, Biosciences Research Laboratory, Fargo, ND 58102-2765, USA.
Comp Biochem Physiol A Mol Integr Physiol. 2011 Dec;160(4):480-5. doi: 10.1016/j.cbpa.2011.08.004. Epub 2011 Aug 10.
Megachile rotundata (Hymenoptera: Megachilidae), the primary pollinator used in alfalfa seed production, may need to be exposed to low-temperature storage to slow the insects' development to better match spring emergence with the alfalfa bloom. It has been demonstrated that using a fluctuating thermal regime (FTR) improves the tolerance of pupae to low temperatures. Carbon dioxide emission rates were compared between four different FTRs, all with a base temperature of 6°C and a daily high-temperature pulse. Four different high-temperature pulses were examined, 15 or 25°C for 2h and 20°C for 1 or 2h. A subset of pupae at the FTR base temperature of 6°C exhibited continuous gas exchange and, once ramped to 20 or 25°C, shifted to cyclic gas exchange. As temperatures were ramped down from the high-temperature pulse to 6°C, the pupae reverted to continuous gas exchange. The following conclusions about the effect of FTR on the CO(2) emissions of M. rotundata pupae exposed to low-temperature storage during the spring incubation were reached: 1) the high temperature component of the FTR was the best predictor of respiratory pattern; 2) neither pupal body mass nor days in FTR significantly affected which respiratory pattern was expressed during FTRs; 3) cyclic gas exchange was induced only in pupae exposed to temperatures greater than 15°C during the FTR high temperature pulse; and 4) a two hour pulse at 25°C doubled the number of CO(2) peaks observed during the FTR pulse as compared to a two hour pulse at 20°C.
圆叶切叶蜂（膜翅目：切叶蜂科）是紫花苜蓿种子生产中主要的传粉昆虫，可能需要进行低温贮藏以减缓昆虫的发育速度，使其与紫花苜蓿的开花期更好地匹配。已经证明，使用波动热环境（FTR）可以提高蛹对低温的耐受性。比较了四种不同的 FTR 之间的二氧化碳排放率，所有 FTR 的基础温度均为 6°C，且每天都有高温脉冲。检查了四个不同的高温脉冲，分别为 15 或 25°C 持续 2 小时和 20°C 持续 1 或 2 小时。在 FTR 基础温度 6°C 下的一组蛹表现出连续的气体交换，一旦升温到 20 或 25°C，就会转变为周期性气体交换。当温度从高温脉冲降至 6°C 时，蛹恢复为连续气体交换。关于 FTR 对圆叶切叶蜂蛹在春季孵化期间低温贮藏过程中 CO(2)排放的影响得出以下结论：1）FTR 的高温部分是预测呼吸模式的最佳指标；2）蛹的体质量或在 FTR 中的天数均不会显著影响在 FTR 期间表达的呼吸模式；3）仅在 FTR 高温脉冲期间暴露于 15°C 以上温度的蛹才会诱导周期性气体交换；4）与 20°C 时的两小时脉冲相比，25°C 时的两小时脉冲使 FTR 脉冲期间观察到的 CO(2)峰值数量增加了一倍。
