Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA.
J Insect Physiol. 2010 May;56(5):480-7. doi: 10.1016/j.jinsphys.2009.05.020. Epub 2009 Jul 9.
Like all terrestrial organisms, insect eggs face a tradeoff between exchanging metabolic gases (O(2) and CO(2)) and conserving water. Here I summarize the physiology underlying this tradeoff and the ecological contexts in which it may be important. The ideas are illustrated primarily by work from my laboratory on eggs of the sphingid moth Manduca sexta. In particular, I discuss: (1) dynamic changes in metabolic demand and water loss during development; and (2) how the eggshell layers and embryonic tracheal system control the traffic of gases between the embryo and its environment. Subsequently, I identify three areas with interesting but unresolved issues: (1) what eggs actually experience in their microclimates, focusing particularly on the leaf microclimates relevant to eggs of M. sexta; (2) how egg experience influences whether or not hatchling larvae succeed in establishing feeding sites on host plants; and (3) whether Hetz and Bradley's [Hetz, S.K., Bradley, T.J., 2005. Insects breathe discontinuously to avoid oxygen toxicity. Nature 433, 516-519] oxygen toxicity hypothesis for discontinuous gas-exchange cycles applies to insect eggs.
与所有陆生生物一样，昆虫卵在代谢气体（O(2)和 CO(2))交换和水分保存之间面临权衡。本文总结了这种权衡的生理学基础以及它可能重要的生态背景。这些观点主要通过我实验室对鳞翅目夜蛾 Manduca sexta 的卵的研究来阐述。具体而言，我讨论了：（1）在发育过程中代谢需求和水分损失的动态变化；以及（2）卵壳层和胚胎气管系统如何控制胚胎与其环境之间气体的流动。随后，我确定了三个具有有趣但尚未解决的问题：（1）卵在其微环境中实际经历了什么，特别关注与 M. sexta 卵相关的叶片微环境；（2）卵的经历如何影响幼虫是否成功在宿主植物上建立取食点；以及（3）Hetz 和 Bradley 的[Hetz, S.K., Bradley, T.J., 2005. Insects breathe discontinuously to avoid oxygen toxicity. Nature 433, 516-519]间断气体交换循环的氧气毒性假说是否适用于昆虫卵。
