> Again, I am leaning toward BBs having more problems than honeybees in the field, but so far there is nothing definitive.
* I started looking at stuff about bumble bees and immediately hit upon contradictory presentations.
1) bumble bee colonies may benefit from greater overall floral abundance, richness, or relative dominance of resource species. We found that floral dominance, rather than the overall abundance or richness of floral resources, was the most important local factor for colony growth and reproduction.
2) We examined the effects of landscape composition, including land-cover diversity and percent semi-natural habitat, on wild bee abundance and species richness within apples, a pollinator-dependent crop. Our results suggest that diverse landscapes support spring wild bees by providing flowers throughout the entire foraging period and diverse niches to meet different species’ requirements.
Essentially these two are stating the opposite. 1) says "A single flowering plant species ... in high relative abundance" was best for the bumble bees while 2) says "Surrounding landscape diversity positively affected both wild bee abundance and richness within orchards during bloom."
* On the topic of pesticides and bumble bees, the views are more consistent:
3) To determine exposure of wild bumblebees to pesticides in agricultural and urban environments through the season, specimens of five different species were collected from farms and ornamental urban gardens in three sampling periods. Overall, our results show that wild bumblebees are exposed to multiple pesticides when foraging in agricultural and urban landscapes.
4) We deployed colonies of Bombus impatiens, a native and common species, in order to relate colony performance to orchard pesticide use. Sentinel bumble bee colonies at orchards with high toxicity scores produced fewer, and smaller, workers. Our results demonstrate that certain bee taxa may have a higher exposure or sensitivity to on-farm pesticide applications, and could therefore be vulnerable in agroecosystems.
These two agree that bumble bees and wild bees in general are at risk in agricultural and urban environments, which we knew. The point is, each study forms a piece of the overall picture, none can be considered definitive. Life is like that.
sources
1) Biological Conservation 206 (2017) 217–223
2) Landscape Ecol (2016) 31:1523–1535
3) Environmental Pollution 222 (2017) 73e82
4) J Insect Conserv (2015) 19:999–1010
PLB
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