The effect of developmental temperature on olfaction in a moth revealed by its interaction with body mass

There is a growing interest in the effects of climate warming on olfaction, as temperature may affect this essential sense. In insects, the response of the olfactory system to developmental temperature might be mediated by body size or mass because body size and mass are negatively affected by developmental temperature in most ectotherms. We tested this hypothesis of a mass-mediated effect of developmental temperature on olfaction in the moth <i>Spodoptera littoralis</i>. We measured the olfactory sensitivity of male to female sex pheromone and five plant odors using electroantennography. We compared males reared at an optimal temperature (25°C with a daily fluctuation of ± 5°C) and at a high temperature (33 ± 5°C) close to the upper limit of <i>S. littoralis</i>. On average, the olfactory sensitivity of males did not differ between the two developmental temperatures. However, our analyses revealed an interaction between the effects of developmental temperature and body mass on the detection of the six chemicals tested. This interaction is explained by a positive relationship between antennal sensitivity and body mass observed only with the high developmental temperature. Our results show that the effect of developmental temperature may not be detected when organism size is ignored.

随着温度可影响这一至关重要的感官，气候变暖对嗅觉的影响正受到日益广泛的关注。在昆虫中，嗅觉系统对发育温度的响应可能受体型或体重介导，因为多数外温动物的体型与体重会随发育温度升高而降低。我们以斜纹夜蛾（*Spodoptera littoralis*）为研究对象，验证了发育温度通过体重介导影响嗅觉的这一假说。我们利用触角电位仪（electroantennography）测定了雄虫对雌性性信息素以及五种植物气味的嗅觉敏感性，并比较了分别在适宜温度（25℃，每日波动±5℃）与接近该物种生存上限的高温（33±5℃）下饲养的雄虫。整体而言，两种发育温度下雄虫的嗅觉敏感性并无显著差异。然而，我们的分析显示，发育温度与体重对六种受试化学物质的检测效应存在交互作用；该交互作用可由仅在高温发育条件下观察到的触角敏感性与体重间的正相关关系解释。我们的研究结果表明，若忽略生物体型因素，可能无法观测到发育温度的真实效应。