Department of Biological Sciences, North Dakota State University, Fargo, ND, USA.
Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, USA.
Environ Entomol. 2022 Oct 21;51(5):958-968. doi: 10.1093/ee/nvac062.
Megachile rotundata (F.) is an important pollinator of alfalfa in the United States. Enhancing landscapes with wildflowers is a primary strategy for conserving pollinators and may improve the sustainability of M. rotundata. Changing cold storage temperatures from a traditionally static thermal regime (STR) to a fluctuating thermal regime (FTR) improves overwintering success and extends M. rotundata's shelf life and pollination window. Whether floral resources enhance overwintering survival and/or interact with a thermal regime are unknown. We tested the combined effects of enhancing alfalfa fields with wildflowers and thermal regime on survival and macronutrient stores under extended cold storage (i.e., beyond one season). Megachile rotundata adults were released in alfalfa plots with and without wildflower strips. Completed nests were harvested in September and stored in STR. After a year, cells were randomly assigned to remain in STR for 6 months or in FTR for a year of extended cold storage; emergence rates were observed monthly. Macronutrient levels of emerged females were assessed. FTR improved M. rotundata survival but there was no measurable effect of wildflower strips on overwintering success or nutrient stores. Timing of nest establishment emerged as a key factor: offspring produced late in the season had lower winter survival and dry body mass. Sugars and glycogen stores increased under FTR but not STR. Trehalose levels were similar across treatments. Total lipid stores depleted faster under FTR. While wildflowers did not improve M. rotundata survival, our findings provide mechanistic insight into benefits and potential costs of FTR for this important pollinator.
圆叶切叶蜂（Megachile rotundata (F.)）是美国紫花苜蓿的重要传粉者。通过增加野花来丰富景观是保护传粉者的主要策略，并且可能提高圆叶切叶蜂的可持续性。将传统的静态热环境（STR）转变为波动的热环境（FTR），可以提高越冬成功率，延长圆叶切叶蜂的货架期和授粉期。然而，目前还不清楚野花资源是否能提高越冬成活率，以及是否会与热环境相互作用。我们测试了在紫花苜蓿田中增加野花和热环境对延长冷藏期（即超过一个季节）下的生存和大量营养物质储存的综合影响。在有和没有野花带的紫花苜蓿田中释放成年圆叶切叶蜂。在 9 月收获已完成的巢穴，并在 STR 中储存。一年后，细胞被随机分配到 STR 中储存 6 个月或 FTR 中储存一年的延长冷藏期；每月观察出蜂率。评估出蜂雌蜂的主要营养物质水平。FTR 提高了圆叶切叶蜂的存活率，但野花带对越冬成活率或营养物质储存没有明显影响。巢的建立时间是一个关键因素：在季节后期产卵的后代冬季存活率和干体重较低。在 FTR 下糖和糖原储存增加，但在 STR 下没有增加。海藻糖水平在各处理组之间相似。FTR 下总脂储存消耗得更快。虽然野花并没有提高圆叶切叶蜂的存活率，但我们的研究结果为 FTR 对这种重要传粉者的益处和潜在成本提供了机制上的见解。
