Organic Farming Kills Bees? Study Fails to Show This

By Josh Bloom — Oct 07, 2015
A new study suggests that certain plant-based (organic) pesticides that are used in organic farming kill bees something that they're not supposed to do. But the study is flawed. Although these botanical pesticides do kill bees, the conditions under which they were tested render the entire study meaningless.

Screen Shot 2015-10-07 at 4.21.32 PMWe constantly debunk bad studies that are anti-chemical, anti-GMO, pro-organic, etc.

Why? Because they are either poorly done, and/or they're complete garbage.

This time, there's a study which apparently condemns organic farming, which despite the fictitious concept and name isn't what it seems to be. Chemicals are used in organic farming, just different ones than are used in conventional farming.

But fair is fair, so when a cautionary "anti-organic" farming paper that is full of flaws comes out, it's fair game. (Good luck using "fair" more times in one sentence.)

One just did. A paper entitled "Acute Toxicity and Sublethal Effects of Botanical Insecticides to Honey Bees" was just published in the Journal of Insect Science.

Like many other papers of questionable value or ones where the press just get's it wrong the headlines, if taken at face value, are misleading.

Are extracts of certain botanicals, some of which are used as insecticides, also killing bees? (They are not supposed to be.) Yes. Does this have any relevance to when they are used under real-life conditions? You can't tell. This is the essential flaw in the study its design.

Upon first glance, it seems obvious that a number of organic pesticides are killing bees, according to Vânia M. Xavier and colleagues from the Instituto Federal de Educação, in Espirito Santo, Brazil.

The group examined the effect of various botanical oils on Apis mellifera L. the bee species that is the main pollinator of cultivated plants. The graph below suggests that these pesticides are killing plenty of bees.

Screen Shot 2015-10-07 at 3.30.22 PM

Although the botanical pesticides that were studied collectively killed roughly 50 percent of adult bees, depending on the chemical that was used, it is far from clear that these tests have any relevance to real life.

In the essay, the bees were kept in a Petri dish for 72 hours, and either exposed to, or fed a single dose of, the botanical pesticide. The amount wasn't even the same for every chemical. The concentration ranged from 0.3 mL to 10 mL per liter of water.

Right away, there is a red flag a single-dose study. In the absence of testing at multiple doses, a dose-response relationship cannot be established. This is an important factor in determining whether a given test is valid. Had the bees been subjected to different concentrations of the chemicals, one would expect to see more deaths with increasing concentration, and vice-versa. This was not done.

Furthermore, is it not at all clear whether the conditions or amount of the chemical in the Petri dish simulates in any way what a bee might encounter while pollinating plants.

The authors state just this: "We used the insecticides at the concentrations recommended by the manufacturer (Natural Rural Industria e Comercio de Produtos Organicos e de Controle Biologico LTDA, Araraquara, São Paulo State, Brazil)."

Other bee behaviors were measured, including weight gain, walking distance, and walking speed. These behaviors were also impacted by the presence of the botanical pesticides.

By the end of the paper, we know exactly one thing: That the six organic pesticides tested are toxic to bees at some dose the exact same argument that we make when evaluating the toxicity of any chemical, natural or otherwise: "The dose makes the poison."

Does organic farming kill bees? It may or may not. This study doesn't answer the question.

Josh Bloom

Director of Chemical and Pharmaceutical Science

Dr. Josh Bloom, the Director of Chemical and Pharmaceutical Science, comes from the world of drug discovery, where he did research for more than 20 years. He holds a Ph.D. in chemistry.

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