Neonicotinoids And Disease In Bees And Other Non-Target Invertebrates

Bayer Cropscience market a product for Termites called Premise 200 SC.  Previously, I have outlined some of the ways in which the company’s marketing literature is revealing in its description of how the neonicotinoid Imidacloprid, works to kill insects, and thus parallels are drawn between the claims made for effects on termites versus potential effects on bees.  

This page can be found How do neonicotinoids work?

The following is a continuation of the information, looking at not only bees, but some other insect species.

Why it matters

Termites are social insects, ant live in colonies even larger than honey bees – as many as a million or more, and have many behaviours in common with other non-target species.

Bayer CropScience describe ways in which their neonicotinoid kills termite colonies.  A wide range of realistic field and lab studies indicate similar effects on bees and other invertebrates.  So how credible is it for industry to claim these independent field and lab trials on bees are erroneous? 

Is it credible that imidacloprid conveniently kills termites in the ways outlined by Bayer Cropscience, yet conveniently has no such negative effects on bees and other non-target insects?

I think this uncomfortable question needs to be asked continually of our politicians, regulators, the media and farmers.  And if you have not read it already, please see my page about non-target insects and patents for pesticides.

Bayer CropScience Marketing & Product Claims And Their Relevance To Bees And Other Invertebrates

Bayer CropScience Product Claim Premise 200SC (imidacloprid) leaflet:

”Premise 200 SC is a systemic insecticide which acts as a contact and stomach poison.  When termites come in contact with this non-repellent product in the treated zone, the stop tunnelling, stop feeding, grooming and they become disoriented, they will be infected by soil fungi and die”.


”The termite are susceptible to disease and fungi found in soil.  A principle part of their defence system is their grooming habits, allows the termites to get rid of the fungal spores before these spores germinate and cause disease of death.  Premise 200SC interferes with this natural process by lowering defence to nature’s own weaponry.”

(I.e. These marketing claims confirm that low doses of Imidacloprid hamper the termite’s ability to groom itself, and this ultimately kills termites, because it increases susceptibility to pathogenic soil fungi.  It also therefore confirms that ‘low doses’ are ultimately therefore effective at killing – even at the edge of a treated zone).


  • Read more about neonicotinoids and grooming in bees (called hygienic behaviour) as a method of self-defence against diseases and fungi, as well as mites here.  

  • Although other insects do not suffer from Varroa attacks, they do nevertheless have their own mites and diseases to contend with, such as different strains of nosema in bumble bees.

  • Countless studies confirm high prevalence of various bee diseases in cases of 'colony collapse disorder' (or CCD).

  • The relationship between neonicotinoids and disruption to grooming in insects and invertbrates, and their resulting vulnerability to disease, has been noted in published studies such as:

    • Galvanho et al, 2012: Imidacloprid Inhibits Behavioral Defences of the Leaf-Cutting Ant Acromyrmex subterraneus subterraneus (Hymenoptera:Formicidae)  (Ants are in the same insect order as bees – i.e. Hymenoptera)

      From the Abstract:

      “Leaf-cutting ants have evolved a range of defensive strategies which complicate the use of entomopathogens for their control. One of these behavioural strategies is self-grooming, which increases when ants detect the presence of fungal conidia on their integuments. We have previously shown that insecticides, when used at ultra-low concentrations, can be synergists of entomopathogenic fungi.  It is possible that certain insecticides could modify ant behavior in a way that increases the chances of a fungal infection taking hold”.

      From the conclusion:

      “Behavior modification by exposure to low concentrations of insecticide could render leaf-cutting ants more susceptible to infection by entomopathogenic fungi as they fail to eliminate the conidia from their integuments, which under normal circumstances are quickly removed by efficient self-grooming”.

    • Santos et al 2006: Selection of entomopathogenic fungi for use in combination with sub-lethal doses of imidacloprid: perspectives for the control of the leaf-cutting ant Atta sexdens rubropilosa Forel (Hymenoptera: Formicidae).

      “Insects treated with 10 ppm IMI [Imidacloprid] were observed to have reduced locomotor activity 24 h after exposure to the insecticide.

      The LC50 of IMI was 154.3 ppm. Subsequent tests were carried out to evaluate the combination of a sub-lethal dose of IMI (10 ppm) and infection by CG24 (1 · 107 conidia ml–1).

      Mortality due to fungal infection alone was 43.3%. Mortality of insects treated with IMI followed by exposure to the fungus was 64.3%. These results indicate that IMI significantly increases the susceptibility of ants to infection by B. bassiana CG24”.

    • Albrecht M. Koppenhöfer et al in 2000, Synergism of imidacloprid and entomopathogenic nematodes against white grubs: the mechanism:

      "The major factor responsible for synergistic interactions between [LOW DOSE] imidacloprid and entomopathogenic nematodes appears to be the general disruption of normal nerve function due to imidacloprid resulting in drastically reduced activity of the grubs.

      This sluggishness facilitates host attachment of infective juvenile nematodes. Grooming and evasive behavior in response to nematode attack was also reduced in imidacloprid-treated grubs."

      "Brushing (legs or mouth parts swept across body)……and chewing ….occurred significantly more often in grubs not treated with imidacloprid in the presence of nematodes and this response was reduced by 42--70% after imidacloprid treatment."

Other insects, from butterflies to flies and beetles, all engage in grooming.  In addition to which, insects other than termites naturally make contact with soil. 

Various bees, flies and beetles nest in the soil and of course, insects will land, rest or drink from puddles on the surface of soil, and hence may, like termites, have the opportunity to come into contact with pathogenic soil fungi.

There Is Evidence Linking Neonicotinoids With  Bee Diseases

A number of studies have highlighted relationships between neonicotinoid pesticides and mortality in bees due to pathogenic nosema:

  • Cédric Alaux et al: Interactions between Nosema microspores and a neonicotinoid weaken honeybees (Apis mellifera) – Published 2009; Environmental Microbiology.
  • Cyril Vidau et al: Exposure to Sublethal Doses of Fipronil and Thiacloprid Highly Increases Mortality of Honeybees Previously Infected by Nosema ceranae - Published 2011; PLoS ONE
  • Jeffery S. Pettis et al: Pesticide exposure in honey bees results in increased levels of the gut pathogen Nosema – Published 2011; Naturwissenschaften.

The EFSA Panel on Plant Protection Products - EFSA Journal 2012; 10(5):2668 commented:

Indeed, it has been shown that low levels of some pesticides may have synergic actions with diseases such as Nosema. Finding diseases in test colonies, which were healthy before the experiment, and not finding such diseases in control colonies, can imply a synergic effect of pesticides and diseases”.

Evidence of Nosema In The UK


In 2008, the UK National Bee Unit  has conducted some study into nosema.  You can read more about it national bee unit and nosema here.


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