73.4 Saturday, Jan. 5 Thermal time: a tool for predicting climate-induced shifts in native bee phenology NATER, O.H.A.*; DILLON, M.E.; Univ. of Wyoming, Laramie; Univ. of Wyoming, Laramie firstname.lastname@example.org
Climate change can decouple the relationship between insect pollinators and their host plants by differentially shifting their phenologies (abundances over time), raising fear of a potential ‘pollinator crisis’. For many insects, spring emergence is directly dependent on temperature, but we lack data on the relationship between climate and phenologies of most pollinators. Here we present a novel thermal time approach to estimate climate change-induced shifts in the spring emergence of four locally abundant native bee taxa (Agapostemon angelicus/texanus, Lasioglossum Dialictus spp., Lasioglossum trizonatum and Halictus rubicundus) in southeast Wyoming. We used 2011 bee abundance data to estimate degree days necessary for 50% population emergence. These degree-day estimates accurately predicted 2012 emergences to within ten days. Since 1975, annual mean, minimum, and maximum temperatures in the area have increased by 1.3, 2.7, and 1.3 °C respectively. Based on 2011 degree-day estimates and assuming no evolution, we estimate springtime phenology of native bees to have advanced by roughly two weeks over the same period. While this approach is not perfect, likely because it does not account for other abiotic and biotic phenological drivers, it is nevertheless a straightforward, low-cost tool for predicting insect species’ responses to climate warming. In light of the paucity of historical data for most species of interest, this approach could prove useful for identifying and mitigating potential disruption of crucial plant-pollinator interactions.