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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, 24 Jul 2013 19:59:59 -0400
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Many of us have been saying repeatedly that all the emphasis on neonics distracts from other problems, some of which may be far more serious. Fungicides are presumed safe to bees, but when stored in the hive can have serious consequences.

> We found insecticides and fungicides in all, and herbicides in 23.6% of, pollen samples. Insecticides present in pollen collected by the bees came from seven categories. We found oxadiazines in 10.5%, neonicotinoids in 15.8%, carbamates in 31.6%, cyclodienes in 52.6%, formamidines in 52.6%, organophosphates in 63.2%, and pyrethroids in 100% of pollen samples. Both neonicotinoids and oxadiazines were present only in pollen collected by bees in apple orchards. Within a sample, pollen fungicide loads were significantly higher than loads of herbicides or any of the insecticide categories.

> A pollen sample’s fungicide load significantly affected Nosema prevalence among bees fed that pollen, but pesticide diversity did not. Nosema infection was more than twice as likely (relative risk .2) in bees that consumed these fungicides than in bees that did not. Research on the sub-lethal effects of pesticides on honey bees has focused almost entirely on insecticides, especially neonicotinoids. In our study, neonicotinoids entered the nest only via apple pollen. However, we found fungicides at high loads in our sampled crops. 

> The significant increase in Nosema infection following exposure to the fungicides in pollen we found therefore indicates a pressing need for further research on lethal and sub- lethal effects of fungicides on bees. 

This last part is especially interesting, considering that there is evidence that fumagillin also increases Nosema infection. Fungicides and antibiotics may be hurting the bees' internal microbiota, rendering them unable to defend against pathological microbes.

SOURCE:
Pettis JS, Lichtenberg EM, Andree M, Stitzinger J, Rose R, et al. (2013) Crop Pollination Exposes Honey Bees to Pesticides Which Alters Their Susceptibility to the Gut Pathogen Nosema ceranae. PLoS ONE 8(7): e70182. doi:10.1371/journal.pone.0070182

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