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Implications of the restriction on the neonicotinoids - imidacloprid, clothianidin and thiamethoxam on crop protection in oilseeds and cereals in the UK

RESEARCH REVIEW 77 

Implications of the restriction on the neonicotinoids: imidacloprid, clothianidin and thiamethoxam on crop protection in oilseeds and cereals in the UK 

by
Caroline J Nicholls HGCA, Agriculture and Horticulture Development Board, Stoneleigh Park, Kenilworth, Warwickshire CV8 2TL

Summary

On 24 May 2013 a restriction on the use of three pesticides (clothianidin, imidacloprid and thiamethoxam) belonging to the neonicotinoid group was adopted by the European Commission. The restriction will come into force as of 1 December 2013 and will be reviewed (though not necessarily rescinded) within two years. It targets pesticides used in the treatment of crops attractive to bees and for cereals, with the exception of uses in greenhouses and uses after flowering. Of the crops of interest to HGCA, the Commission’s decision affects all oilseed crops, all maize crops, and any cereal crops sown between January and June.

Neonicotinoid seed treatments are used in winter and spring oilseed rape (OSR) to control cabbage stem flea beetle (CSFB), flea beetle, peach-potato aphid (which transmits turnip yellows virus (TuYV)) and turnip sawfly.

Approximately 67% of the total OSR area is affected by CSFB. The average yield loss of the area affected is about 1%, although in some instances yield losses may be much higher. Without insecticides, the calculated annual tonnage lost from CSFB is 15,336 t, costing the industry approximately £5 million per year (0.7% of the total crop value). Without neonicotinoid seed treatments, foliar-applied pyrethroid insecticides are the only alternative; however, CSFB resistance to pyrethroids has been identified in Germany and has the potential to spread to the UK. Pyrethroids already account for 88% of the most commonly used insecticides in OSR. Any additional pyrethroid use should be cautious in order to preserve their efficacy and reduce risks of insecticide resistance developing.

Approximately 60% of the total area of OSR is affected by TuYV. The average yield loss from TuYV in untreated crops is 15%, although yield losses of up to 30% can occur. Without insecticides, the calculated annual tonnage lost from TuYV is 206,010 t, costing the industry approximately £67 million per year (9% of the total crop value). There are no alternative insecticides currently available: neonicotinoids are the only approved OSR insecticide for autumn use to which the peach-potato aphid has not developed resistance to in the UK.

Neonicotinoid seed treatments are used in winter and spring linseed to control flax flea beetles. Unfortunately, there is a lack of information on area affected or yield loss caused by the beetle. As with OSR, pyrethroid insecticides are the only alternatives available.

There are cost implications of not treating seed with neonicotinoids. The reduced costs from not treating certified OSR seed with clothianidin-containing formulations is £12.90 per ha and for hybrid OSR is £9.55 per ha. The reduced cost from not treating certified seed with imidacloprid-containing formulations for linseed is £9.00 per ha. For farm-saved OSR seed, the reduced cost from not 5 treating with thiamethoxam-containing formulations is £16.50 per ha. For linseed, the reduced cost from not treating farm-saved seed with imidacloprid-containing formulations is £8 per ha. The reduced cost for not treating certified seed will be much more than from farm-saved as OSR and linseed are mostly grown from certified seed (79% and 92% of the cropping area respectively). There are no published figures on what proportion of farm-saved seed is treated with a neonicotinoid treatment. For OSR, the additional product costs calculated for additional pyrethroid sprays as alternatives to neonicotinoids for were: £2,387,459 for 1 pyrethroid spray; £4,774,919 for 2 pyrethroid sprays; £7,162,378 for 3 pyrethroid sprays; and £9,549,837 for 4 pyrethroid sprays. For linseed, the additional product costs calculated for additional pyrethroid sprays as alternatives to neonicotinoids for were: £103,042 for 1 pyrethroid spray; £206,084 for 2 pyrethroid sprays; £309,125 for 3 pyrethroid sprays; and £412,167 for 4 pyrethroid sprays.

Maize is treated with clothianidin to control frit fly and wireworm. The only current alternative control is methiocarb, for frit fly. The cropping area of grain maize is relatively low compared with forage maize and other cereals, so the impact will be lower compared to other European countries where maize is widely grown.
Early sown (September to October) cereals tend to be at high risk of barley yellow dwarf virus (BYDV). These are still likely to, and can, receive a neonicotinoid seed treatment. Spring cereals do not have a current approval for neonicotinoid treated seed. It is, therefore, unlikely that the Commission’s decision will affect the control of BYDV in cereals.

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