Wild Bee Decline Connected to Commercial Use of Neonicotinoid Treated Crops in England
17 Aug 2016 --- The long-term bee decline in the English countryside has been linked to exposure to neonicotinoid seed treated oilseed rape crops, according to research.
The Centre for Ecology & Hydrology used data provided by Fera Science Ltd and the Bees, Wasps and Ants Recording Scheme, to examine changes in the occurrence of 62 wild bee species with oilseed rape cropping patterns between 1994 and 2011. This is the time span in England for wide-scale commercial use of neonicotinoids.
These are a group of insecticides that can be applied to seeds prior to planting which means the active compound is expressed systemically throughout the growing plant. It can lead to potential ingestion where pollinators, including bees, feed on the pollen and nectar of treated crops.
Scientists found that on average the decline was three times stronger among species that regularly feed on the crop, like the buff-tailed bumblebee (Bombus terrestris), compared to other species that forage on a variety of different floral resources.
According to the research, this indicates that oilseed rape is a principle mechanism of neonicotinoid exposure in wild bee communities. The data suggests that neonicotinoids use does correlate with wild bee biodiversity losses at a national scale and has implications for the conservation of bee communities in intensively farmed landscapes.
These latest findings are in addition to smaller-scale and shorter-term exposure studies in the past which have identified negative effects of neonicotinoids on honeybees and a limited number of commercially-bred wild bee species.
Of the five species of bee that were examined (which also included the spined mason bee or Osmia spinulosa and furrow bee or Lasioglossum fulvicorne), neonicotinoid use was equivalent to at last 20 percent of local population extinctions of wild bees.
“As a flowering crop, oilseed rape is beneficial for pollinating insects. This benefit however, appears to be more than nullified by the effect of neonicotinoid seed treatment on a range of wild bee species,” says lead author, Dr. Ben Woodcock.
“Although we find evidence to show that neonicotinoid use is a contributory factor leading to wild bee species population decline, it is unlikely that they are acting in isolation of other environmental pressures. Wild bees have undergone global declines that have been linked to habitat loss and fragmentation, pathogens, climate change and other insecticides.”
Entomologist and conservationist Dr. Dino Martins, a native Kenyan, is one of the world’s leading experts in his field. Last year he was honored with the prestigious Whitley Award for exceptional conservation work as a pollinator champion, helping to drive a cultural change in African farming practices to improve yields, and teach farmers how to work with pollinators, not against them.
Investigating the effects of pesticides on pollinators is a key issue for him and he praises the Centre for Ecology & Hydrology’s latest study.
“These are exactly the sort of studies that we need that show across different species, extended time scales and spatially broad, the effects of pesticides on pollinators,” he tells FoodIngredientsFirst.
“Using the data from the recording scheme makes a great connection with the broader citizen science movement and shows that clever meta-analysis of large data-sets such has been done here is key to better understanding pollinator dynamics at a landscape level.”
The research adds to an extensive body of evidence that will inform the European Food Standards Authority review of the risks neonicotinoid pesticides pose to bees, which is due for completion next January.
by Gaynor Selby
