Heat resistance variability in the Lebanese bee fauna

Wild bees are facing many environmental challenges that are reshaping their distributions and even causing extinctions. One of the common threats is climate change leading to a higher frequency of extreme climatic events such as heat waves. We focused on the bee fauna of the eastern Mediterranean country of Lebanon and assessed intra- and interspecific variability of the heat stress resistance in correlation with dry body weight, altitude, and collection date. We used the time before heat stupor (THS) at 40 °C in semi-controlled conditions as a proxy for heat resistance. We found significant interspecific differences in heat resistance, and a positive correlation with dry weight in some taxa. At the intraspecific level, there was a significant difference in heat resistance between sexes for some species. Also, dry/fresh weights, altitude, and collection date were correlated to a higher heat resistance in some taxa. In the context of global changes, we argue that we need heat tolerance metrics for a better understanding of bee decline and to enhance conservation measures at regional scale.