Wild bumble bee colony abundance, scaled by field size, predicts pollination services

Although bee visitation rate to flowers is often used to assess both pollination services and bee abundance, the abundance of social species needs to be assessed by quantifying the number of colonies instead of the number of foraging individuals. Because accurately quantifying the number of wild bee colonies can be difficult, the relationship of visitation rates provided by foragers and the abundance of colonies contributing those foragers from the surrounding landscape is poorly documented for social species.  Here, we use genetic methods and statistical inference to estimate the abundance of wild colonies of Bombus impatiens in the surrounding landscape providing foragers to 30 commercial pumpkin (Cucurbita pepo) fields over 4 years across a 13,000 km2 area in Pennsylvania (U.S.A.).  We show that the abundance of wild colonies in the surrounding landscape providing foragers per field (colony abundance per field) ranges from 291 to 829 colonies per field. Furthermore, colony abundance ...