Fresh evidence links neonicotinoid
pesticides to death of the honeybee spurs calls for banning the pesticides Dr. Mae-Wan Ho
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Increase vulnerability to infection at
The honeybee’s vulnerability to infection is
increased by the presence of imidacloprid, even at the most microscopic doses.
This new research result by Dr Jeffrey Pettis and his team at the US Department
of Agriculture’s Bee Research Laboratory has remained unpublished for nearly
two years, according to an ‘exclusive’ report in UK’s newspaper, The
Independent . Increased disease infection happened even when the levels
of the insecticide were so tiny that they could not be detected in the bees
that the researchers had dosed.
insecticides, introduced since the early 1990s, are increasingly used on crops
in the US, Britain and around the world. Bayer, the German chemicals giant that
developed the insecticides insists that they are safe for bees if used
properly, but they have already been widely linked to bee losses. Imidacloprid
was Bayer's top-selling insecticide in 2009, earning the company £510 m.
Link to colony collapse of the honeybee
Neonicotinoids have attracted growing
controversy since their introduction by Bayer in the 1990s, and have been
blamed by some beekeepers and environmental campaigners as a potential cause of
Colony Collapse Disorder (CCD), first observed in the US in 2006, in which bees
disappear from hives en mass (see  Mystery of
Disappearing Honeybees, SiS 34). Prof. Joe
Cummins at ISIS was among the first to link neonicotinoid insecticides to CCD
( Requiem for the
Honeybee , SiS 34);
which had led to swift action on the part of the German Government in banning
the pesticides ( Emergency Pesticide Ban
for Saving the Honeybee, SiS 39).
Between 20 and 40
per cent of American hives have been affected, and CCD has since been observed
in several other countries from France to Taiwan, though it has not yet been
detected in Britain , where the area of cropland treated with neonicotinoids
has gone from 0 in 1993 to more than 2.5 m acres in 2008.
The chemicals have been banned already in France, Germany and Italy. In Britain, the Co-op has banned their use in farms from which it sources
fruit and vegetables, but the British Government has refused to ban or suspend
Matt Shardlow, commented on the Pettis study: “This new research from America confirms that at very, very low concentrations neonicotinoid chemicals can make a
honeybee vulnerable to fatal disease. If these pesticides are causing large
numbers of honeybees, bumblebees, solitary bees, hoverflies and moths to get
sick and die from diseases they would otherwise have survived, then
neonicotinoid chemicals could be the main cause of both colony collapse
disorder and the loss of wild pollinator populations.
"The weight of
evidence against neonicotinoids is becoming irresistible – Government should
act now to ban the risky uses of these toxins."
The UK Government
is to debate the impact on bees and other insects of the new generation of
pesticides linked to bee mortality . The Government will be called on to
suspend all neonicotinoid pesticides approved in British, pending more
exhaustive tests of their long-term effects on bees and other invertebrates.
The subject will be raised in an adjournment debate in the House of Commons
Tuesday 25 January 2011 on a motion tabled by Martin Caton, the Labour MP.
Caton, a former
agricultural scientist said the evidence is growing that neonicotinoids were a problem,
but the testing regime for the compounds in Britain and Europe was not rigorous
enough. “I think they should be suspended on the precautionary principle while
we improve it.” He added: “We’re talking about a threat to our whole ecosystem,
when invertebrates are being lost at the sort of rate that has happened in
There is already a
call for banning neonicotinoid pesticides in the US and European Union that has
attracted 1 069 781 signatures so far 
Unpublished research repeated and published
Dr Pettis told The Independent his
research was completed almost two years ago , “but it has been too long in
getting out.” He has now been submitted his manuscript to a new journal for
publication. However, in a comment to the news article, Pettis made clear that
he is not alleging that his research is being suppressed, but that “the review
process on the paper has simply been lengthy.”
Pettis and a member
of his team, Dennis van Engelsdorp, of Penn State University, both leaders in
research on CCD, and have spoken about it at some length in a film about bee
deaths that has been shown widely in Europe, but not yet in Britain or the US.
In The Strange
Disappearance of The Bees, made by the American film-maker Mark Daniels,
Pettis and van Engelsdorp reveal that they exposed two groups of bees to the
well-known bee disease agent Nosema. One of the groups was also fed tiny
doses of imidacloprid. There was a higher uptake of infection in the bees fed
the insecticide, even though it could not subsequently be detected, which
raises the possibility that such a phenomenon occurring in the wild might be
Although the US study remains unpublished, French researchers at the National Institute for Agricultural Research
in Avignon have independently carried out similar research and published their
study in the journal Environmental Microbiology. They stated : “We
demonstrated that the interaction between nosema and a neonicotinoid
(imidacloprid) significantly weakened honeybees.”
Synergistic effects between pathogen and
The results of the French group confirmed
that synergistic effects between Nosema and neonicotinoid pesticide weakened
the honeybee, causing increased mortality . The activity of glucose oxidase,
which enables the bees to sterilize colony and brood food, was significantly
decreased only by the combination of both compared with controls, not with the
two groups treated singly by either Nosema or neonicotinoid pesticide.
To reduce harm
caused by chemical pesticides, more ‘eco-friendly’ biological controls have
been developed using microbial pathogens including viruses, bacteria and fungi,
especially fungi. When fungal pathogens are administered with sub-lethal doses
of pesticides, they interact synergistically and result in much more effective killing
of insect pests such as termites, thrips, and leaf-cutter ants.
Imidacloprid, a systemic
neonicotinoid pesticide is widely used around the world on food crops, and has
been implicated in the loss of honeybee in France, where one hive in two
contain residues of imidacloprid, 30 percent of honey and 26 percent of bees,
albeit at sub-lethal levels of about 5 mg/kg.
Simultaneously, a parasitic
microsporidia fungus, Nosema ceranae, has been associated with bee
losses in the USA, and Spain. This prompted the researchers in Avignon to carry out their investigations.
The study was designed to look at possible effects on 1) individual mortality and energetic demands; 2) individual immunity; and 3)
social immunity. Energetic demands were assessed by sucrose consumption as Nosema
alters host nutrient store and feeding behaviour. Individual immunity was
assessed by total haemocyte (blood cell) count (THC) and phenoloxidase (PO) enzyme activity. PO plays a central role in invertebrates’ immune reaction, being
involved in the encapsulation of foreign object through melanisation. THC gives
an indirect measure of basal cell immune activity as the blood cells are involved
in phagocytosis and the encapsulation of a parasite. Glucose oxidase (GOX)
enzyme activity is measured as an indicator of social immunity, as it is
involved in sterilizing the colony, and its antiseptic product, hydrogen
peroxide is secreted into larval food and honey to inhibit pathogen
The results showed that imidacloprid significantly increased
mortality over controls even at the lowest concentration used (0.7 mg/kg), but
mortality was always highest when the bees were simultaneously exposed to Nosema.
At the lower concentrations previously designated sub-lethal (0.7 and 7 mg/kg), the
synergistic effects of the pesticide with Nosema were additive; but at
the highest concentration of imidacloprid (70 mg/kg), the effects were
closer to multiplicative. Sucrose consumption showed a similar pattern.
THC and PO, as indicators of individual immunity were not
significantly affected by the treatments, though the possibility remains that
they may not be adequate indicators of individual immunity.
However, glucose oxidase, as indicator of social immunity, was
significantly decreased only when imidacloprid and Nosema were present
together. This decrease in social immunity could explain the higher mortalities
in bees simultaneously exposed to the two agents.
Alaux C, Brunet J-L, Dussaubat C, mondet F,
Tchamitchan S, Cousin M, Brillard J, Baldy A, Belzunces LP and Le Conte Y.
Interactions between Nosema microspores and a neonicotinoid weaken honeybees (Apis
millifera). Environmental Microbiology 2010, 12, 774-82.
Cummins J. Parasitic fungi and pesticides act
synergistically to kill honeybees? Science in Society 35,
Rory Short Comment left 26th January 2011 22:10:28 I am not a bee keeper, thus my comment is more to do with our society's current attitudes toward human activities which may or may not be harmful to the ecosystem or parts thereof.
Basically our value system is seriously skewed in a life threateningly dangerous direction. By giving more importance to the monetary profits to be earned from some innovation and down playing, or ignoring, the possibility of ecological harm arising from the same innovation we are, as society, behaving as though our very life support systems are less important to us than the opportunity for somebody to make money.
This dangerous approach probably arises because the majority of people are totally ignorant of our dependence, for our very survival, on the continued existence of the ecosystem within which our species evolved.
Dave Comment left 26th January 2011 22:10:51 https://secure.avaaz.org/en/save_the_bees/?cl=914333688&v=8201
This site seems to be a viable method of quantifying public opinion on important matters. Consider clicking on the link, joining, and voting.
Todd Millions Comment left 29th January 2011 22:10:03 Dr Mae Wan-I find it interesting that similar problems,are noted with the synthetic crysathenum insecticides,as these synthetic nicotindes.Both were quickly approved as 'equivelent'-yet were patentable in and of themselves(not just the manufacturing process.).
While caution had too be used in the natural source originals-the toxicity and the persistence of these synthetics is much grater-any reason?
Mae-Wan Ho Comment left 30th January 2011 08:08:05 Hi Todd,
Your point about the greater persistence of synthetics is very important. Many synthetics are designed to resist natural breakdown so that their action lasts longer. They are literally xenobiotics, ie, foreign to the biosphere, so no enzymes have evolved to break them down. Natural insecticides, on the contrary, can be broken down.
gudrun scott Comment left 31st March 2012 14:02:00 today there is a lengthy article in the NY times with more current research-- no mention of a ban in Europe.
Avril Burt Comment left 6th April 2013 08:08:46 I see from the Dutch research that Neonics remain in the plant and return to the soil and soil water on plant death.
What happens to the products of these plants e,g Rapeseed Oil in our food?? And honey??
Elizabeth Adamowicz Comment left 29th April 2013 16:04:30 Hello it seems to me that we must save our bees but most of the public may not know what steps to take, eg which flea treatments are safe alternatives, and which products to avoid in order to help save our bees and environment.
Any further advice would be welcome to families and companies able to help the cause...?
Ps is the e-cigarette safe in terms of our bee population?
m.h.mehta Comment left 13th June 2013 15:03:31 we should look for alternative biopestcides-botanical/microbial.Need more inputs/debate & expert comments.