Department of Environmental Science and Policy (ESP), University of Milan, Via Celoria 26, 20133, Milan, Italy.
Sci Rep. 2024 Apr 18;14(1):8960. doi: 10.1038/s41598-024-58804-2.
Increased temperature and fragmentation of green spaces in urban areas could drive variations in functional traits of insects. Such morphological shifts may occur for sensory systems, which were previously reported to be prone to change with habitat characteristics in non-urban contexts. Here, we measured traits related to the visual and antennal sensory systems in the bees Halictus scabiosae and Osmia cornuta and the wasp Polistes dominula along an urbanisation gradient within Milan (Italy). We hypothesised that fragmentation could filter for better visual properties, and that higher temperature could filter for fewer thermoreceptors and more olfactory hairs. While controlling for body size, results show subtle but appreciable responses to urbanisation in one or more traits in all species, though not always supporting our hypotheses. O. cornuta shows marginally higher ommatidia density and smaller ommatidia diameter (associated with better visual resolution) in more fragmented sites, as well as marginally fewer thermoreceptors in hotter sites, in agreement with our two predictions. On the other hand, H. scabiosae has marginally smaller antennae and P. dominula has smaller eyes at warmer locations, and the wasp also has smaller antennae and 9th flagellomeres in more fragmented areas. Perhaps higher temperatures accelerate development of sensory system at higher speed than the rest of body in these two species. Our results represent the first evidence of urbanisation effects on the visual and antennal sensory systems of bees and wasps and underline how such effects may involve a much broader bouquet of traits then previously observed.
城市地区温度升高和绿地碎片化可能会导致昆虫功能特征的变化。这种形态变化可能会发生在感觉系统上，以前有报道称，在非城市环境中，感觉系统容易随栖息地特征而变化。在这里，我们在米兰（意大利）的城市化梯度内测量了蜜蜂 Halictus scabiosae 和 Osmia cornuta 以及黄蜂 Polistes dominula 与视觉和触角感觉系统相关的特征。我们假设碎片化可以筛选出更好的视觉特性，而更高的温度可以筛选出更少的热敏感受器和更多的嗅觉毛。在控制了体型大小的情况下，结果显示，所有物种的一个或多个特征都表现出微妙但明显的城市化响应，但并不总是支持我们的假设。O. cornuta 在碎片化程度更高的地方表现出略微更高的小眼密度和更小的小眼直径（与更好的视觉分辨率相关），以及在温度更高的地方略微更少的热敏感受器，这与我们的两个预测一致。另一方面，H. scabiosae 的触角略微较小，P. dominula 在温暖的地方眼睛较小，黄蜂的触角和第 9 个鞭节也在碎片化程度较高的地方较小。也许在这两个物种中，较高的温度以比身体其他部位更快的速度加速了感觉系统的发育。我们的研究结果首次证明了城市化对蜜蜂和黄蜂的视觉和触角感觉系统的影响，并强调了这种影响可能涉及比以前观察到的更广泛的特征。
