Six years of wild bee monitoring collections data using Blue Vane traps in Southern Pennsylvania, USA

Turley NE, Biddinger DJ, Joshi NK, López-Uribe MM. 2022. Six years of wild
bee monitoring shows changes in biodiversity within and across years and
declines in abundance. Ecology and Evolution.    Wild
bees form diverse communities that pollinate plants in both native and
agricultural ecosystems making them both ecologically and economically
important. The growing evidence of bee declines has sparked increased
interest in monitoring bee community and population dynamics using
standardized methods. Here, we studied the dynamics of bee biodiversity
within and across years by monitoring wild bees adjacent to four apple
orchard locations in Southern Pennsylvania, USA. We collected bees using
passive Blue Vane traps continuously from April to October for six years
(2014-2019) amassing over 26,000 bees representing 144 species. We
quantified total abundance, richness, diversity, composition, and
phylogenetic structure. There were large seasonal changes in all measures
of biodiversity with month explaining an average of 72% of the variation
in our models. Changes over time were less dramatic with years explaining
an average of 44% of the variation in biodiversity metrics. We found
declines in all measures of biodiversity especially in the last 3 years,
though additional years of sampling are needed to say if changes over time
are part of a larger trend. Analyses of population dynamics over time for
the 40 most abundant species indicate that about one third of species
showed at least some evidence for declines in abundance. Bee family
explained variation in species-level seasonal patterns but we found no
consistent family-level patterns in declines, though bumble bees and sweat
bees were groups that declined the most. Overall, our results show that
season-wide standardized sampling across multiple years can reveal nuanced
patterns in bee biodiversity, phenological patterns of bees, and
population trends over time of many co-occurring species. These datasets
could be used to quantify the relative effects that different aspects of
environmental change have on bee communities and to help identify species
of conservation concern.