Impact on Scottish crops if the molluscicide metaldehyde is withdrawn
A targeted analysis of the impact of insecticide withdrawals in Scotland, in the context of alternative control options
Insecticides are commonly used in Scottish agricultural, horticultural, forestry production, and for amenity and natural environment management purposes. Over the last 10 years, approximately 50% of UK insecticide active substances have been withdrawn due to increasing concern over human health and environmental impacts. Some of these losses will be mitigated by using alternatives but their practicality and cost under Scottish conditions is unknown. This project analysed current crop production patterns and insecticide use in combination with how likely different insecticides are to be withdrawn and provided stakeholder views on the impacts of any such losses on their industry, including other control methods that may be adopted.
This report sets out estimates for the crop loss and value to Scottish crop production should the molluscicide metaldehyde be withdrawn. This would leave ferric phosphate as the only available chemical control option. Short term losses are negligible as the substitution of ferric phosphate carries no additional treatment costs and has equivalent efficacy. Longer term there is some risk should resistance arise to this single site mode of action active, and ferric phosphate (although of lower mammalian toxicity to metaldehyde) has some environmental impacts of its own.