Progeny of Osmia lignaria from distinct regions differ in developmental phenology and survival under a common thermal regime

Abstract

Many insects, including some bees, have extensive subcontinental distributions that can differ in climatic conditions. Within and beyond these distributions, humans intentionally transport beneficial insects, including bees, to non-natal geographic locations. Insects also are experiencing unprecedented climatic change in their resident localities. For solitary bees, we know very little about the adaptive plasticity and geographic variation in developmental physiology that accommodates the different climates experienced within distributional ranges. Osmia lignaria Say (Hymenoptera: Megachilidae) is a widely distributed North American spring-emerging bee being developed as a managed pollinator for tree fruit crops, including almonds. We examined the development and survival of O. lignaria progeny that were descended from populations sourced from southern California, western Washington, and northern Utah, and then were reared together under an hourly and weekly temperature regime simulating those of a California almond-growing region. We found that developmental physiologies of Washington and Utah progeny were generally similar. However, California progeny developed slower, were more metabolically active, and survived better under California conditions than did populations native to regions at higher latitudes. Regardless of geographic origin, cocooned adults managed under prescribed thermal regimes emerged faster and lived longer after wintering. Progeny of parents from different regions exhibited some acclimatory plasticity in developmental phenologies to a novel climatic regime, but overall their responses reflected their geographic origins. This outcome is consistent with their developmental phenologies being largely heritable adaptations to regional climates.