Neonicotinoids - the continuing story.
Dave Goulson, author of the lovely book, A Sting in the Tale, and Professor of Biology at Sussex, has published an important paper in Journal of Applied Ecology.
An overview of the environmental risks posed by neonicotinoid insecticides
Journal of Applied Ecology 2013 doi: 10.1111/1365-2664.12111
This is one of the nice journals that allows you to read it on-line for free.
Here's the link.
And here's the Summary:
- 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.
- However, the prophylactic use of broad-spectrum pesticides goes against the long-established principles of integrated pest management (IPM), leading to environmental concerns.
- 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.
- Although vertebrates are less susceptible than arthropods, consumption of small numbers of dressed seeds offers a route to direct mortality in birds and mammals.
- 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.
Stuff we need to know - Haber's Law and neonicotinoids
Get your head round time dependent cumulative toxicity of neonics with Dr Henk Tennekes. It's stuff we need to know: http://www.youtube.com/watch?v=wx5Oh-Vvrwo&feature=youtu.be
The simple story is that the pesticide industry, government regulators and most of the rest, judge the toxicity of an insecticide by how much is needed to kill an insect straight away. The Median Lethal Dose (LD50) test is, simply put, a measure of how much of the chemical is needed to kill 50% of the creatures it is applied to.
However, neonicotinoids are cumulative poisons, binding to receptors in nerve cells. If the insect is exposed to tiny doses, far less than the LD50 dose, but continuously over a long period of time, the poisons will accumulate and eventually kill the creature.
This LD50 test of toxicity carried out by the agro-chemical industry and accepted by government regulators is just not the appropriate measure. Once time dependent cumulative toxicity is taken into account it becomes obvious that there is no safe dose below which neonics can safely be allowed in the environment.
As an introduction to measures of toxicity one might do worse than reading the Wikipedia pages on Median Lethal Dose and, in this context of neonics, the very important Haber's Law.
Or you might just share my opinion that neonicotinoids are an unnecessary catastrophic disaster in the making and should not be used, at all, ever. Not even a little bit.