Until the early 1990s plant protection products (PPPs) were usually sprayed externally over plants, to kill insect pests; this posed the major risk of acute exposure to pesticides for honeybees. However, the development of pesticide application technologies moved away from externally sprayed PPPs, towards internally distributed systemic pesticides, applied as seed dressings; this systemic technology aimed to confine the PPP concentrations to within the tissues of the treated plant. However, these systemic technologies have radically changed the potential for exposure of non-target vertebrates and invertebrates to these substances.
The new era of pesticides
The existing Environmental Risk Assessment (ERA) for bees and pesticides, carried out before the introduction into the market of PPPs, was designed in a different era; it was designed for externally applied PPPs that were sprayed onto crops and had no systemic -lived, acute acting and disappeared from the crop within hours or days.
The creation of systemics represent a quantum leap in pesticides - A technological revolution in terms of (a) toxicity (b) persistence in the crop (c) persistence in soil and water (ex. Clothianidin has a half-life of 19 years in clay soils) (d) ability to trans-locate into other untreated crops and wildflowers which are far from the point of application.
This last point means that there is a qualitative difference in that the old PPPs only contaminated neighbouring crops if the spray drifted on the wind and even then the toxicity disappeared in a week. The new systemics can migrate via water far away from the field where they are applied and they can affect bees feeding on wildflowers around the edges of the field or possibly m a quantum leap in the potential for toxic contamination.
To access the full document click here