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Posted 04 November 05


Dear Beekeepers

I am writing to alert you to the issue of the widespread use of a relatively new systemic insecticide called Imidacloprid which has been banned throughout France since 2000 as a result of the loss of thousands of bee colonies in the period from 1997 - 2004 and a dramatic drop in honey harvests there. Imidacloprid is used as a seed-dressing on virtually every acre of oilseed rape in the UK as well as on sugar beet; winter wheat, winter barley and winter oats; forestry plantations, plant nurseries and in garden centres.

Dr Miles Thomas of the Central Science Laboratory reports that Imidacloprid was used on over 1.4 million acres of crops in the UK in 2004. The chemical is a systemic insecticide and specifically attacks the nervous system; as a neuro-toxin it has a lethal effect on bees at just 5-10 part per billion in nectar and pollen. However, one independent French study found it had sub-lethal behavioural effects on bees at just 0.1 ppb - a dosage of 50-100 times less than the lethal effect.

The pesticide is dusted onto the seeds of oilseed rape and other crops but it migrates throughout the growing plant and is found in: sap, leaves, nectar and pollen. Imidacloprid is neuro-toxic - it attacks the nervous system of all animals including invertebrates: worms, insects, bees, butterflies, ladybirds etc. It also poisons birds. The 'target' species are aphids, flea beetles and any soil invertebrates which attack seeds and roots. However, Imidacloprid also kills non-target-species including bees, earthworms, woodlice, caterpillars, moths etc.


Imidacloprid is lethal to bees at a staggeringly low level of contamination: the manufacturer Bayer originally claimed that the pesticide only killed bees at levels of 5,000 nanogrammes per kg, but later independent studies confirmed that it kills bees outright at levels of just 10 nanogrammes per kilo ( 10 parts per billion). However, independent French research - see below - reports that, since it attacks the nervous system directly, it does not need to kill bees outright in order to affect a colony. Imidacloprid has been shown to be present in the nectar and pollen of treated oilseed rape flowers at levels from 3-7 nanogrammes per kg (ppb). Dr Bonmatin reports that at just 0.1 nanogrammes per kg there were pronounced sub-lethal effects on foraging bees including: inability to navigate or forage properly. It seems logical that long before it kills bees, Imidacloprid will affect complex behaviours like flight, navigation, vision, smell etc, and crucially in the case of queens - mating and orientation flights.


It seems logical that if bees are collecting nectar and pollen that is contaminated with Imidacloprid at just 3 to 5 parts per billion (ppb) there will be a bio-concentration effect as nectar is evaporated and concentrated into honey, or mixed with pollen to feed larvae. The initial poisoning of foraging bees may be sub-lethal; however, once Imidacloprid is introduced into the hive and concentrated as honey, it may then be fed to larvae over a period of a week of their growth stage, so the dosage which the larva accumulates will progressively rise. Similarly, worker bees will feed the queen with contaminated nectar over a prolonged period and she could be receiving a dose which, titlehough not acutely lethal, would progressively damage her nervous system as a cumulative poison burden.

This could explain why some UK beekeepers have experienced unusual queen losses in 2005: failure to mate, failure to return from mating flights, supercedure of young queens in their first season, abnormal egg laying patterns, drone laying young queens, death of brood in the cells. Separating such effects from the additional impact of virus disease caused by varroa would be very difficult.


Imidacloprid is highly persistent in the soil once it has been used on a field. The International Bee Research Project (see below) found that two years after Imidacloprid was last-used in a field of oilseed rape, the pollen and nectar of the new rape crop was still contaminated with the chemical at a level that has been shown to affect bees. Similarly, it is highly persistent in water and is equally lethal to aquatic vertebrates, invertebrates and insects including: dragonflies, water fleas, water beetles etc. Could this be affecting farm ditches and freshwater ponds in arable crop areas? It seems highly likely that, since it affects insectivorous birds, it would also affect insect eating frogs, newts, toads etc.


Imidacloprid kills virtually 100% kill of all earthworms and soil invertebrates in any treated field. Given the poison's long-persistence in the soil, this would imply that any treated field remains ecologically sterile for several years after treatment. Logically this could be a major causative factor in the catastrophic decline of farmland birds and especially insectivores which has been noted by BTO and RSPB. Over 1.4 million acres of UK arable crops were treated with this systemic, highly persistent nerve poison in 2004; this means that virtually the entire UK arable cropland area is well on the way to becoming ecologically sterile.


In the period 1997-2000, French beekeepers and bee-farmers experienced massive colony losses (in the tens of thousands of hives) and a dramatic fall in honey harvest in areas where Imidacloprid was first used on sunflowers and oilseed rape. These losses were progressive and geographically linked to the introduction of the pesticide. In areas where it was not used there were far fewer colony losses and the honey harvest was normal; in areas where the pesticide was introduced for the first time, the bee-losses were coincident in time and place. As a result of massive protests from the French beekeepers, backed by well-researched studies from a number of regional and national science institutes, the French government banned the chemical in 2000. However, distributors and farmers were allowed to 'use up existing stocks' until 2004, so the current year's honey harvest is the first which has been largely free of Imidacloprid. One can assume that Bayer has been lobbying intensively for removal of the ban - given that £400 million is at stake in Europe if the ban continues; undoubtedly they will have backed up their lobbying with strong scientific studies claiming the chemical is harmless. However, the French government has so far refused to rescind the ban, which should give us food for thought here in the UK.

Imidacloprid is produced by Bayer Crop Sciences and total world sales of the chemical in 2004 were valued at 600,000,000 Euros. It is marketed in the UK under various trade names including:

  • 'Chinook' for seed dressing of oil-seed rape seed.
  • 'Gaucho and Montur' for seed dressing of sugar beet seed.
  • 'Prestige' for dressing of potato seed before planting.
  • 'Confidor' for treatment through irrigation water in greenhouses (ornamental plants, tomatoes, cucumber and sweet pepper).
  • 'Merit Forest' for treatment of forest plants against insect attacks.
  • My concerns are threefold:

    1. As a beekeeper I am concerned that we are beginning to see evidence of unusual collapses of bee colonies in the UK which mirrors, on a smaller scale, those experienced by French beekeepers in the period 1997-2004. The French government ban on the use of Imidacloprid was agreed in 2000 but only became effective in 2004. The latest reports are that colony recovery and honey harvest in France was abrupt and distinct in 2004-2005 after the complete ban on Imidacloprid. More studies are underway.
    2. As a conservationist I am concerned that the large-scale use of this highly toxic, systemic and persistent insecticide in the UK is effectively sterilising fields of all soil-invertebrate life including: earthworms, beetles, ladybirds, butterflies, moths etc. This has profound ecological implications, especially for insectivorous birds and mammals.
    3. Imidacloprid is highly persistent in the environment and is absorbed into all parts of the crop-plant: pollen, nectar and seeds. If collected by bees it is progressively concentrated in honey as the nectar is evaporated. It seems likely that it will be present in sunflower and rape-seed oil, - even if in small quantities. As a neuro-toxin this may have implications for the food chain and human hetitleh.

    Banned in France - Approved in the UK?

    I became aware of Imidacloprid due to articles about massive loss of bee colonies in France, Switzerland, Sweden and Canada. I append a number of articles from government agencies, bee -research laboratories and other sources in those countries. Beekeeping is a very large and influential industry in France and concern at the economic loss from colony-deaths was very widespread. Large demonstrations were held in Paris and intense lobbying went on. The outcome was that the use of Imidacloprid as a seed-dressing for sunflowers, oilseed rape and potatoes was banned in France and it remains so.

    Situation in the UK

    When I consulted the UK Pesticides Safety Directorate online database I discovered that 'Imidacloprid' is the dominant seed-treatment for oilseed rape, marketed under the trade name 'CHINOOK' in the UK or 'GAUCHO' in France. It is also the main see-treatment for sugar beet, winter wheat, winter barley and winter oats.

    The obvious question is: why does a pesticide that has been banned througho ut France continue to be approved for very wide scale use across the UK?

    Moreover, why does BBKA Enterprises persist in accepting significant funding from the manufacturers of Imidacloprid? They do not endorse this specific pesticide but they do endorse other pesticides by the same manufacturer as being "bee friendly".In my view this is completely unethical and wrong as a matter of principle - it also places BBKA in an extremely invidious and vulnerable position. Once an organisation has pocketed cash from a pesticide manufacturer for endorsing one product, it would be extremely difficult to publicly oppose another far more dangerous product - as is evident from the continuing silence on this issue from BBKA."

    Impact on Beekeeping in the UK

    Currently there is growing concern in the UK about the unexpected collapse of bee colonies in summer (a time when they normally thrive) and a sporadic incidence of failure of queen bees to mate or prosper. As yet the evidence is sporadic and a national survey/ study is urgently needed but if the pattern follows that observed in Sweden, France and Canada, it seems a reasonable hypothesis that Imidacloprid may be a causal factor. Imidacloprid is a systemic insecticide which attacks the nervous system of all invertebrates; the target pests are flea beetles and wireworms etc but beneficial species such as bees, earthworms and beetles are also killed. The pesticide is dusted onto seeds before they are planted and is used on a worldwide scale on crops including: sunflowers, oilseed rape, potatoes, wheat etc.

    French and Swiss researchers found that after Imidacloprid is dusted onto sunflower seed, or oilseed rape, it permeates the entire plant, including the nectar, pollen and seeds . The loss of bee colonies in France was concentrated in sunflower or oilseed rape growing areas. Imidacloprid only needs to be present at 10 parts per billion to kill bees outright. Bees exposed to 5 ppb simply do not return to their hives.



    A definitive Swiss study reported:

    "Klaus Wallner confirmed in his study of Imidacloprid prepared Phacelia with a burden of 50 g/hectare, that the bee's honey-sac average contamination was 5ppb and the pollen taken from the 'pollen baskets' of the bees contained 7ppb. The centrifuged honey contamination level could not (yet) be ascertained. The level was less than the 3ppb traceability level for honey.

    Independent French Study:

    In a report issued by the French Agriculture Ministry it was stated: "Depending on the sunflower variety, the residues in the flower on the 65th day (at start of blossom period) varied between 2.5ppb (Pharon) and 8.7ppb (Natil). These values could possibly be higher at point of harvest. The sunflower pollen is contaminated at an average level of 3ppb (up to 11 ppb max.). In untreated plantings (sunflower, rape and corn), which were planted in Imidacloprid-contaminated-soil, up to 7.4ppb was detected in the flowers.

    "The Bayer study produced a mortality rate due to Imidacloprid for bees as follows: The LD 50 (the lethal dose which kills 50% of test organisms within 48 hours) lay between 3.7 and 40.9 nanogrammes (ppb) of Imidacloprid per bee. Long-term-injury was investigated by Dr. Bonmatin.

    He achieved an LD 50 after 8 days by feeding individual bees an Imidacloprid/ sugar solution of just 0.1 ppb. The substance showed itself to be highly toxic when delivered over time."


    Graham White
    3 Oxenrig Farm Cottages

    TD12 4EY

    Tel: 01890 882 713

    e-mail Graham


    More input ...

    Hi John

    Imidacloprid is only one of a number of neurtoxic systemic insecticides known as neonicotinoids. Five are now marketed in New Zealand. Two are used on kiwifruit preblossom. Actara (Thiamethoxam) and Calypso (Thiacloprid) are two that are being looked at in connection with some deaths of bees in kiwifruit pollination. Their LD50s are less than Gaucho so have'nt been detected in current tests available. A method of evaluating systemic insectcides prior to registration is needed. Current assessments only look at toxic effects (deaths) less emphasis ion non toxic effects (behavioural changes in behaviour that can lead to bee colony decline or deaths (sublethaldoses)

    Ian S Stewart
    Bee Farm

    (13 January 06)

    ................................. and more


    Sent: Monday, January 09, 2006 6:04 PM

    Subject: Imidachoprid

    Dear Paul

    Thank you for the information about Imidachoprid. About ten years ago the insect life in our rivers and lochs suffered a catastrophic decline and salmon and trout ceased to spawn successfully. There are now almost no trout in Tweed and associated waters and what salmon there are can only spawn above farming levels. I wrote to the Tweed Commissioners at the time but got no acknowledgement.

    There is now very little insect life in the whole of the Border area and bird life is limited. We no longer have to wash insects from the front of our cars and number plates. During the last two years I maintained correspondence with MSPs and almost anyone I thought could do something to get our Government interested. How a people could allow their country to be devastated in this


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