EXPERT REACTION: Bee health - new pesticides to worry about

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A new class of pesticides that could replace neonicotinoids may be bad for bumblebee colonies, say UK researchers. Sulfoximine-based pesticides have been approved for use in Australia, China and Canada and are effective in dealing with insect pests that are resistant to neonicotinoids. The researchers found that bumblebee colonies treated with sulfoximine had a 54 per cent reduction in offspring, producing significantly fewer worker bees and reproductive males. The authors suggest that sulfoxaflor exposure could lead to similar environmental impacts on pollinators as neonicotinoids, with important knock-on effects for agriculture.

Journal/conference: Nature

DOI: 10.1038/s41586-018-0430-6

Organisation/s: Royal Holloway University of London

Media Release

From: Springer Nature

Ecology: Sulfoximine pesticides impact bumblebee colony fitness

A novel class of pesticides, expected to be a key replacement for neonicotinoids, may have sub-lethal effects on bumblebee colonies, reports a paper published online in Nature this week.

Sulfoximine-based pesticides have been shown to be effective in targeting neonicotinoid-resistant species and have been approved for use in China, Canada and Australia, with licence applications progressing in several EU member states. However, the two classes of pesticide share a common biological mode of action and the sub-lethal effects of sulfoximines on pollinators have not yet been fully investigated.

Harry Siviter and colleagues found that bumblebee colonies exposed to the sulfoximine pesticide sulfoxaflor in a laboratory setting produced significantly fewer workers and reproductive male bumblebees once released into a field setting. Twenty-five colonies were exposed to conservative doses of sulfoxaflor for two weeks during the early growth phase, and differences between these colony populations and the 26 control colonies began to emerge 2–3 weeks post-exposure and persisted until the end of the colony lifecycle. Treated colonies experienced a 54% reduction in reproductive offspring, suggesting that the exposure of a small cohort of bumblebees in the early stages of a colony’s life history may have long-term consequences for colony fitness. However no changes in foraging behaviour or pollen load were observed.

The authors suggest that sulfoxaflor exposure could lead to similar environmental impacts on pollinators as neonicotinoids in the absence of evidence-based legislation. They call for regulatory bodies to assess both the lethal and non-lethal consequences of novel insecticides before licencing them for use.

Expert Reaction

These comments have been collated by the Science Media Centre to provide a variety of expert perspectives on this issue. Feel free to use these quotes in your stories. Views expressed are the personal opinions of the experts named. They do not represent the views of the SMC or any other organisation unless specifically stated.

Dr Katja Hogendoorn is a native bee expert and Research Associate within the School of Agriculture, Food and Wine at the University of Adelaide

This is a carefully done study, which demonstrates delayed effects of sulfoxaflor consumption on bumblebee colony reproduction. The guidelines for spraying sulfoxaflor suggest that, once dried, the crop has low - medium acute oral and contact toxicity for adult worker honey bees. This study underscores, once more, the need for more elaborate testing, as the outcome of present tests does not exclude (a) sub-lethal or delayed effects on honey bees; (b) detrimental consequences for other beneficial insect species such as solitary bees and parasitic wasps, or (c) other collateral damage for invertebrates or animals higher up the food chain.

All insecticides are, funnily enough, to some extent detrimental to insects! Growing food plants in monocultures nearly always requires the control of pests including pest insects. While such control can include the responsible use of insecticides (after appropriate research), there are other ways to control insect pests, such as growing in protected cropping, enhancing biological control and avoiding monocultures. Pesticide companies will keep on pushing their products and try to assure the community that they are safe to use – they make money from their products. Testing of these assertions is required and needs to be independent. In the end, such independent elaborate testing will allow growers and consumers clear choices regarding the level of collateral damage to the environment they are willing to accept.

Last updated: 17 Aug 2018 12:44pm
Declared conflicts of interest:
None declared.

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