By Dave Goulson, published in the Journal of Applied Ecology 2013
1. Neonicotinoids are now the most widely used insecticides in the world. They act systemically,
travelling through plant tissues and protecting all parts of the crop, and are widely
applied as seed dressings. As neurotoxins with high toxicity to most arthropods, they provide
effective pest control and have numerous uses in arable farming and horticulture.
2. However, the prophylactic use of broad-spectrum pesticides goes against the long-established
principles of integrated pest management (IPM), leading to environmental concerns.
3. It has recently emerged that neonicotinoids can persist and accumulate in soils. They are
water soluble and prone to leaching into waterways. Being systemic, they are found in nectar
and pollen of treated crops. Reported levels in soils, waterways, field margin plants and floral
resources overlap substantially with concentrations that are sufficient to control pests in
crops, and commonly exceed the LC50 (the concentration which kills 50% of individuals) for
beneficial organisms. Concentrations in nectar and pollen in crops are sufficient to impact
substantially on colony reproduction in bumblebees.
4. Although vertebrates are less susceptible than arthropods, consumption of small numbers
of dressed seeds offers a route to direct mortality in birds and mammals.
5. Synthesis and applications. Major knowledge gaps remain, but current use of neonicotinoids
is likely to be impacting on a broad range of non-target taxa including pollinators and
soil and aquatic invertebrates and hence threatens a range of ecosystem services.