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Informed Discussion of Beekeeping Issues and Bee Biology

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Subject:
From:
Peter L Borst <[log in to unmask]>
Reply To:
Informed Discussion of Beekeeping Issues and Bee Biology <[log in to unmask]>
Date:
Wed, 15 Jan 2014 10:58:34 -0500
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Focusing on Neonics has caused many people to misunderstand the gravity of the situation. Commercial hives exposed to agriculture are found to contain a wide range of substances, many added by beekeepers. Synergies take place which increases the effects beyond what may be expected from the individual testing of these substances.

> High levels of fluvalinate and coumaphos are co-occuring with lower but significant levels of 98 other insecticides, fungicides and herbicides in pollen. Most noteworthy were the very high levels of the fungicide chlorothalonil in pollen and wax as well as ppm levels of the insecticides aldicarb, carbaryl, chlorpyrifos and imidacloprid, fungicides boscalid, captan and myclobutanil, and herbicide pendimethalin. With an average of 7 pesticides in a pollen sample, the potential for multiple pesticide interactions affecting bee health seems likely. Ten pesticides were found in pollen at greater than one tenth the bee LD50 level indicating that sublethal effects of these toxicants alone are highly likely. -- Pettis et al 2010

> All pesticides at hive-residue levels triggered a significant increase in larval mortality compared to untreated larvae by over two fold, with a strong increase after 3 days of exposure. Among these four pesticides, honey bee larvae were most sensitive to chlorothalonil compared to adults. Synergistic toxicity was observed in the binary mixture of chlorothalonil with fluvalinate at the concentrations of 34 mg/L and 3 mg/L, respectively; whereas, when diluted by 10 fold, the interaction switched to antagonism. Chlorothalonil at 34 mg/L was also found to synergize the miticide coumaphos at 8 mg/L. The addition of coumaphos significantly reduced the toxicity of the fluvalinate and chlorothalonil mixture, the only significant non-additive effect in all tested ternary mixtures. -- Frazier et al 2014

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