How can we ensure honey bees are healthy whilst maintaining maize production and cutting out neonicotinoids?
In the UK (April 2017), the government has refused an application to use neonicotinoids on 167,000 acres of oilseed rape (canola).
A study from Italy suggests that following a ban on neonicotinoids for use on maize, average production remained the same, whilst honey bee deaths reduced significantly.
SGOLASTRA, Claudio PORRINI, Stefano MAINI, Laura BORTOLOTTI, Piotr MEDRZYCKI,
Franco MUTINELLI, Marco LODESANI
Bulletin of Insectology 70 (1): 156-160, 2017: ISSN 1721-8861
In the early 2000s, Italian beekeepers began to report bee-mortality events linked to maize sowing.
Evidence pointed to three neonicotinoids (imidacloprid, clothianidin, thiamethoxam) and a phenylpyrazole (fipronil) used for seed dressing that were dispersed in the environment during sowing.
Following these events, and based on the Precautionary Principle, in September 2008, the Italian Ministry of Health suspended these four active ingredients as maize seed dressing.
Here we show that in Italy after the precautionary suspension, the number of bee mortality events linked to maize-sowing drastically declined.
At the same time, the average annual maize production per hectare remained unchanged.
This finding is indicative of the possibility to maintain stable maize productions without affecting honey bee health status.
The implementation of Integrated Pest Management for maize production is discussed.
Meanwhile, a further study has found that the neonicotinoid thiamethoxam impairs honey bee flight ability (it makes for interesting reading in addition to another recently published study referring to the risks to bees from chronic and acute exposure to pesticides, even when pollen is collected from primarily non-target crops).
Burgio &; James
Scientific Reports 7, Article number: 1201 (2017);
doi:10.1038/s41598-017-01361-8. Published online: 26 April 2017
Pesticides can pose environmental risks, and a common neonicotinoid pesticide, thiamethoxam, decreases homing success in honey bees. Neonicotinoids can alter bee navigation, but we present the first evidence that neonicotinoid exposure alone can impair the physical ability of bees to fly.
We tested the effects of acute or chronic exposure to thiamethoxam on the flight ability of foragers in flight mills.
Within 1 hour of consuming a single sublethal dose (1.34 ng/bee), foragers showed excitation and significantly increased flight duration (+78%) and distance (+72%).
Chronic exposure significantly decreased flight duration (−54%), distance (−56%), and average velocity (−7%) after either one or two days of continuous exposure that resulted in bees ingesting field-relevant thiamethoxam doses of 1.96–2.90 ng/bee/day.
These results provide the first demonstration that acute or chronic exposure to a neonicotinoid alone can significantly alter bee flight. Such exposure may impair foraging and homing, which are vital to normal colony function and ecosystem services.
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