Important report on systemic insecticides and pollinators (2012)

Via a posting by the Virginia Native Plant Society, here is a report (1.5 MB) by the Xerces Society for Invertebrate Conservation, a respected organization which does excellent work regarding insects and especially pollinator conservation topics.

Neonicotinoids are systemic insecticides, i.e. they are absorbed by and get inside the treated plant.  Six neonicotinoid insecticides are used on plants: imidacloprid, clothianidin, thiamethoxam, dinotefuran, acetamiprid, and thiacloprid.  These account for 17% of the global insecticide market (data from 2006).  Page 5 of the report lists common products which include these insecticides.  These are what you will find on the shelf of your local garden store.

This report analyzes the research to date, sets out the facts that have been identified and are supported by an extensive body of research, and identifies what can be inferred from the these facts.  It also identifies the gaps in knowledge that need further investigation, and makes specific recommendations.

Some of the major findings of the report include:

– Several of these insecticides are highly toxic to honey bees and bumblebees.

– Products approved for homeowners to use in gardens, lawns, and on ornamental trees have manufacturer-recommended application rates up to 120 times higher than rates approved for agricultural crops.

– Many neonicotinoid pesticides that are sold to homeowners for use on lawns and gardens do not have any mention of the risks of these products to bees, and the label guidance for products used in agriculture is not always clear or consistent.

– Neonicotinoid residues are found in pollen and nectar consumed by pollinators such as bees and butterflies. The residues can reach lethal concentrations in some situations.

– Neonicotinoids can persist in soil for months or years after a single application. Measurable amounts of residues were found in woody plants up to six years after application.

– Untreated plants may absorb chemical residues left over in the soil from the previous year.

– There is no direct link demonstrated between neonicotinoids and the honey bee syndrome known as Colony Collapse Disorder (CCD).  However, recent research suggests that neonicotinoids may make honey bees more susceptible to parasites and pathogens, including the intestinal parasite Nosema, which has been implicated as one causative factor in CCD.

Lorne Peterson
11 April 2012