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What doesn’t kill you makes you stronger? Not for bees and pesticides!

If you manage to survive and once the pain is gone, you will feel better and stronger than before. But this is not true for bees and pesticides.Some common pesticides used worldwide and approved on the basis of their safety and low toxicity are actually destroying colonies of bumbles and honey bees.

Insects which – whether you like them or not – play a critical role in the reproduction of many edible plants: not many apples will ripen without the help of bees, for example.

These pesticides were approved based on tests showing that low doses would not kill the bees in the short-term. No long-term effects have been taken into account for the approval. But as two studies published in last week issue of Science magazine showed long-term effects of low-dose pesticides are complex and imply a substantial risk for bumbles and honey bees and should be taken into account.

This is how it works. Neonicotinoids are a very selective ‘new’ kind of insecticides which  impairs insects’ neurological system and disrupt their behaviour. They efficiently kill aphids and sucking pests. They are systemic, meaning that they enter the plant system and reach all its organs from within; as a result pesticide residues will end up contaminating pollen and nectar too.

Slow Killer: Thiamethoxam, pesticides commonly used in flowering crops like oilseed rape, maize or sunflower.  A sophisticated study conducted in France using microchips attached to honey bees showed that Thiamethoxam is not as harmless as expected. Bees that eat pollen or nectar contaminated with this pesticide, even at very low doses, get lost on their way back home. As a result, they are twice as likely to die within a day, making the colony weaker and under higher risk of collapse (1).

Queens Killer: Imidacloprid, member of the neonicotinoid group, registered for use on over 140 crops in over 120 countries. The second research published by Science Magazine, an experiment with bumble bees in Stirling University in Scotland, showed this insecticide damaging effect even at very low doses on bee colony development and especially on queens (2).  Bumble bees eating food contaminated with tiny amounts of imidacloprid grow less, and as a result their colonies are smaller (8-12% smaller). But importantly, this translates into a disproportionate large decline in number of queens:  one or two queens compared to the 14 in pesticide-free colonies. Queens are fundamental in colony survival, as they are the only ones who survive the winter and can found colonies the following spring.

Pesticide effects might be subtle but not less hazardous. Reading these articles I think of how little we know on the effects of industrial agriculture on biodiversity.

Take for example the genetically engineered (GE) insect-resistant Bt crops. Greenpeace is concerned about impact on non-target insects such as butterflies. The studies performed under the risk assessments for GE crops couldn’t pick up any alarming effect, but they were only looking for how many insects survived the exposure to the Bt toxin, often over a very short time-scale.

Many scientists are instead concerned that GE Bt crops could have subtle effects, and could even affect the learning performance of bees(3). And even more worrying, these consequences might go unnoticed until there’s a major impact on biodiversity.

Bees are vital for food production. We shouldn’t forget this.

Often we hear that pesticides are also vital for high yields. Are they? Clearly not! Millions of farmers across the world are moving away from chemical pesticides and getting high yields.  Ecological farming is a real path out of poverty.

For example in the Indian state of Andhra Pradesh (4) the government is sponsoring what is know as NPM (Non Pesticide Management) on nearly 3.5 million acres, an approach that eliminates the use of chemical pesticides at the large scale. This non-chemical approach increase net economic returns are for farmers, as farmers do not have to spend on expensive inputs. A recent evaluation by the local agriculture university showed that yields have increased too. The success of this project has received the Indian Prime Minister’s attention and Non Pesticide Management projects have being scaled up with the goal of covering 5000 villages and10 million hectares in the next few years.

Also in rich countries growing food without chemicals is feasible. French scientists recently modelled that drastic reductions in pesticide use (30-50%) are possible without affecting yields, or with very small reductions in yields within intensive agriculture areas.

Ecological farming without chemicals is the most promising, realistic and economically feasible solution to the current destructive agriculture model.

We simply cannot rely on chemical pesticides anymore. Even when labelled as ‘low harm’ by chemical companies there are hidden long-term consequences which can be dramatic and definitively won’t make the bees stronger!

As these two new solid science studies show it is time to move away from blind trust in pesticides and start protecting our food, our farmers (and our honey).

Reyes Tirado, Greenpeace International Science Unit


(1)Henry, M. l., Beguin, M., Requier, F., Rollin, O., Odoux, J.-F., Aupinel, P., Aptel, J., Tchamitchian, S. & Decourtye, A. 2012. A Common Pesticide Decreases Foraging Success and Survival in Honey Bees. Science 1215039 Published online 29 March 2012 [DOI:10.1126/science.1215039].

(2)Whitehorn, P. R., O’Connor, S., Wackers, F. L. & Goulson, D. 2012. Neonicotinoid Pesticide Reduces Bumble Bee Colony Growth and Queen Production. Science 1215025 Published online 29 March 2012 [DOI:10.1126/science.1215025].

(3) Ramirez-Romero, R., Desneux, N., Decourtye, A., Chaffiol, A. & Pham-Delègue, M. H. 2008. Does Cry1Ab protein affect learning performances of the honey bee Apis mellifera L. (Hymenoptera, Apidae)? Ecotoxicology and Environmental Safety, 70: 327-333.

(4)Vijay Kumar, T., Raidu, D. V., Killi, J., Pillai, M., Shah, P., Kalavakonda, V. & Lakhey, S. 2009. Ecologically sound, economically viable: community managed sustainable agriculture in Andhra Pradesh, India. The Word Bank and Society of Elimination of Rural Poverty (SERP).

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