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Difference In Larval Pesticide Toxicity across A.m. races— Joe Milone

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  • Difference In Larval Pesticide Toxicity across A.m. races— Joe Milone

    Differences in larval pesticide toxicity - Joe Milone

    North Carolina State University

    Abstract: Honey bee (Apis mellifera) colonies retain residues from many chemicals which results in exposure to multiple pesticides during sensitive developmental stages. The harmful effects of these exposures depends on the susceptibility of bees to a given dose. We compared pesticide susceptibility among 8 North American honey bee breeding stocks using a larval oral exposure assay. To test field-realistic exposures, we selected a mixture of 7 commonly detected insecticides, fungicides, and an herbicide using previously reported pesticide residue data from commercial colonies. We chronically administered diet spiked with the treatment mixture at 4 dose levels during worker larval development in vitro. A Hazard Quotient (HQ) was used to quantify toxicity from the multi-pesticide mixture at each concentration and survivorship to the exposure was compared among the offspring from 30 colonies. The median lethal HQ values for each stock showed a gradient with three clusters of susceptibility. Larvae from stocks know for artificial selection were among the most susceptible to pesticide exposure, while larvae from distinct and unmanaged stocks were found to have higher tolerances. These findings highlight the need to account for stock differences when testing and reporting honey bee toxicology measures. Future work is needed to elucidate the mechanisms driving differential susceptibility to pesticides in honey bees.

    1. Risk = Susceptibility + Exposure
    2. Pesticide Tolerance Ratio
      1. Italians more affected
    3. Residue Analysis
      1. Wax n (sample number) = 108
      2. Miticides & pesticides
    4. Hazard Quotient
      1. HQ = Exposure / L50 + Exposure/L50 (L50 is the level it takes to kill 50% of bee sample)
    5. Method
      1. 7 common compounds were detected in wax
      2. Dose levels
        1. 300
        2. 500
        3. 600
        4. 800
      3. Breeds: Russian, Saskatraz,Italian examples
        1. Included Cradle Forestry and Arnot NY
      4. 30 colonies were sampled
    6. Results - Mortality order (least to most deaths)
      1. Carniolan
      2. Russian
      3. Saskatraz
      4. SDI
      5. Cradle
      6. NY Arnot Forest Swarms
      7. VSH
      8. Italian
      9. VSH were the most susceptible to pesticides. Old world ferals least susceptible
    Kalispell, Montana Zone 4a
    Certified Master Beekeeper