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Quantifying exposure of bumblebees to neonicotinoids and mixtures of agrochemicals - PS2372

Neonicotinoid insecticides are now among the most widely used pesticides in the world, and are routinely used to protect a range of flowering crops such as oilseed rape and sunflowers against herbivores. In the UK, 1.27 million ha of crops were treated with neonicotinoids in 2010. Most are used as a seed-dressing, with the crop plant absorbing the compound as it grows, and hence becoming protected against herbivorous pests. Neonicotinoids are also used as foliar sprays on soft fruit crops, and are widely sold as sprays or granules for garden use on flowers, fruit and vegetable crops. As they are systemic chemicals, low concentrations of neonicotinoids are found in nectar and pollen of treated crops, and hence they are consumed by pollinators. They are also water soluble and persistent, so that detectable quantities have been found in hedgerow / field margin wildflowers near treated crops, although it is not known if this commonly occurs.

Evidence is mounting that exposure of bees to neonicotinoids produces sublethal effects such as reduced navigational ability and reduced fecundity. A recent study by my group demonstrated that exposure of bumblebee nests to levels of imidacloprid which are known to occur in the nectar and pollen of seed-treated oilseed rape resulted in an 85% reduction in output of new queens (Whitehorn et al. 2012). A substantial proportion of wild bumblebee nests are likely to be within foraging range of a treated, flowering crop, so it seems likely that this class of insecticide may be contributing substantially to the much-discussed declines in wild bee populations. There is an urgent need to quantify the sublethal exposure of bumblebees to neonicotinoids, as the first step towards evaluating whether their use is having adverse affects on wild bee populations.

In this project we will investigate levels of neonicotinoids in UK flowering crops and field margin flowers which might be visited by bees, to determine whether dust or neonicotinoids in soil water do commonly occur in flowers near treated crops. We will quantify exposure of bumblebee nests to neonicotinoids by placing young nests into intensive arable farmland, mixed farmland and urban areas, and subsequently examining levels of neonicotinoids in their brood and food stores over a 10 week period, after which the nests will be destructive sampled. Palynological work will establish the main sources of pollen which each nest has gathered. The landscape within a 2 km radius of each nest will be quantified using landsat data and ground truthing to identify the availability of flowering crops or gardens which may act as sources of agrochemicals. We will then go on the analyze levels of neonicotinoids found in workers of 3 contrasting wild bumblebee species. Collectively, these data will allow us to identify the main sources of exposure of wild bumblebee nests to neonicotinoids, and reveal likely levels of exposure. These data are urgently needed if we are to ascertain whether neonicotnoids currently pose a threat to wild bumblebee populations in the UK.
1. Determine levels of neonicotinoids in nectar and pollen of the main UK flowering crops and in a selection of field margin/ hedgerow wildflowers favoured by bumblebees.

2. Quantify the doses of neonicotinoids that bumblebee colonies are exposed to when naturally foraging in UK farmland.

3. Quantify and compare exposure of wild bumblebee species
Project Documents
• FRP - Final Report : PS2372 Final report   (1388k)
Time-Scale and Cost
From: 2013

To: 2016

Cost: £365,728
Contractor / Funded Organisations
University of Sussex
Bee Health              
Insecticide use              
Pesticide use              
Fields of Study
Pesticide Safety