Simmons Leigh W, Lovegrove Maxine, Du Xin Bob, Ren Yonglin, Thomas Melissa L
Centre for Evolutionary Biology, School of Biological Sciences The University of Western Australia Perth Western Australia Australia.
Harry Butler Institute Murdoch University Perth Western Australia Australia.
Ecol Evol. 2023 Jul 3;13(7):e10244. doi: 10.1002/ece3.10244. eCollection 2023 Jul.
Global declines in insect abundance are of significant concern. While there is evidence that climate change is contributing to insect declines, we know little of the direct mechanisms responsible for these declines. Male fertility is compromised by increasing temperatures, and the thermal limit to fertility has been implicated as an important factor in the response of insects to climate change. However, climate change is affecting both temperature and hydric conditions, and the effects of water availability on male fertility have rarely been considered. Here we exposed male crickets to either low or high-humidity environments while holding temperature constant. We measured water loss and the expression of both pre- and postmating reproductive traits. Males exposed to a low-humidity environment lost more water than males exposed to a high-humidity environment. A male's cuticular hydrocarbon profile (CHC) did not affect the amount of water lost, and males did not adjust the composition of their CHC profiles in response to hydric conditions. Males exposed to a low-humidity environment were less likely to produce courtship song or produced songs of low quality. Their spermatophores failed to evacuate and their ejaculates contained sperm of reduced viability. The detrimental effects of low-humidity on male reproductive traits will compromise male fertility and population persistence. We argue that limits to insect fertility based on temperature alone are likely to underestimate the true effects of climate change on insect persistence and that the explicit incorporation of water regulation into our modeling will yield more accurate predictions of the effects of climate change on insect declines.
全球昆虫数量的减少令人深感担忧。虽然有证据表明气候变化正在导致昆虫数量减少，但我们对造成这些减少的直接机制知之甚少。温度升高会损害雄性昆虫的生育能力，而生育的热极限被认为是昆虫对气候变化反应的一个重要因素。然而，气候变化正在影响温度和水分条件，而水分可利用性对雄性生育能力的影响却很少被考虑。在这里，我们将雄性蟋蟀置于温度恒定的低湿度或高湿度环境中。我们测量了水分流失以及交配前和交配后生殖特征的表达。暴露于低湿度环境中的雄性蟋蟀比暴露于高湿度环境中的雄性蟋蟀流失更多水分。雄性蟋蟀的表皮碳氢化合物谱（CHC）并不影响水分流失量，并且雄性蟋蟀不会根据水分条件调整其CHC谱的组成。暴露于低湿度环境中的雄性蟋蟀不太可能发出求偶鸣叫，或者发出的鸣叫质量较低。它们的精包无法排出，并且它们的射精中所含精子的活力降低。低湿度对雄性生殖特征的有害影响将损害雄性生育能力和种群的持续性。我们认为，仅基于温度的昆虫生育能力限制可能会低估气候变化对昆虫持续性的真正影响，并且在我们的模型中明确纳入水分调节将对气候变化对昆虫数量减少的影响产生更准确的预测。
