Initial assessment to understand the effect of air temperature on bees as floral visitors in urban orchards

Abstract

Bees are the most important pollinators and, like many other insects, are facing a global decline that threatens crop pollination services. Both honey bees and some wild bee species are used commercially for pollination, including pollination in blueberry and cherry orchards. In our study, we assessed bee visits to experimental blueberry and cherry orchards immersed in an urban landscape to understand how air-temperature affects the potential contribution of honey bees and wild bees to pollination services. The potential contribution to pollination services was estimated using the Pollination Importance Value index, where the pollen collected by the floral visitor is a determining variable. In our study, bumble bees and honey bees were the most important floral visitors in the orchards, followed by the wild bee Anthophora plumipes. We found that honey bees were affected by changes in air-temperature and their decrease in the potential contribution to pollination services was offset by the niche complementarity provided by bumble bees.

Implications for insect conservation Even small changes in air-temperature can alter bee communities by affecting bee species susceptible to low temperatures. Our work is a first assessment of how climate change may affect the complementarity of pollinator communities in orchards. We suggest that strategies to mitigate local air-temperature changes in urban areas, focusing primarily on these species, could potentially have cascading effects that would support the overall pollination services provided by bee communities.