by Peter McGrath, Michael Norton, and Nina Hobbhahn, The Conversation
First marketed in the late 1990s, neonicotinoid insecticides have become the world's most widely used group of insecticides. They offer lower toxicity to mammals than the insecticides they replaced. But their systemic nature means that all parts of the plant become toxic to insect pests. Even just a coating around seeds offers weeks of protection to a growing crop.
This is great for farmers. But the characteristics that make them so effective have also wreaked enormous collateral damage. Neonics (as they are more familiarly called) are now the most notorious group of insecticides in the world.
Neonics are water soluble and non-selective. This means that they can contaminate the environment, causing collateral damage to non-target organisms. Studies have found that, when neonics are used as seed dressings, up to 95% of the active ingredient doesn't enter the plant. It washes away, contaminating the soil and plants growing in neighboring fields, and leaches into water bodies, where aquatic insects are exposed to it.