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Assessment of toxicity of almond insecticide-fungicide-adjuvant treatments applied on adult honey bees at field relevant concentrations

Walker, Emily K
http://rave.ohiolink.edu/etdc/view?acc_num=osu1618825948672527

Abstract Details

2021, Master of Science, Ohio State University, Environmental Science.
Beekeepers are reporting significant honey bee deaths during and after almond bloom. These losses pose a major problem for the California almond industry because of its dependence on honey bees as pollinators. This research aimed to determine if combinations of agrochemicals applied during almond bloom were a possible explanation for losses reported by beekeepers. Common agrochemical mixtures often include pesticides such as insecticides and fungicides, and pesticide adjuvants, which are added to improve the performance of pesticides. This research was performed in two separate studies which both looked at the acute effects of individual and mixture effects on adult honey bee mortality. The first study looked primarily at insecticide-fungicide mixture toxicity, however, the pesticide adjuvant Dyne-Amic was used in this first study as an introduction to pesticide adjuvant toxicity alone and in combination with pesticides. The second study focused primarily on establishing toxicities for a number of different pesticide adjuvants and later looked at the toxicity of some of these adjuvants in combination with pesticides. In both studies, a Potter Spray Tower was used to mimic the spray application route of exposure and apply widely used pesticide and pesticide adjuvant formulations at field relevant application rates to adult honey bees. Previous research has shown that combinations of fungicide and insecticide active ingredients can be more toxic than the individual pesticides. The first study aimed to test the effects of pesticides and pesticide mixtures to honey bees, using formulated pesticide products sprayed on the bees at field relevant concentrations. Insecticides tested included Altacor and Intrepid and fungicides included Tilt, Pristine, Luna Sensation and Vangard, all of which are widely used in almonds during bloom. In the first study, synergistic toxicity was observed when the fungicide Tilt (a.i. propiconazole) was applied with the insecticide Altacor (a.i. chlorantraniliprole), though neither was toxic when the treatments were applied individually. When the spray adjuvant Dyne-Amic was applied individually it resulted in significant acute mortality at concentrations slightly above the maximum recommended field application rate. When combined with pesticides, mortality was observed when Dyne-Amic was combined with the fungicide Pristine (a.i. pyraclostrobin and boscalid). Addition of Dyne-Amic also increased toxicity of the Tilt and Altacor combination. These results suggest that application of Altacor and Tilt together with an adjuvant, all at the recommended field application rates, could cause significant acute mortality in adult honey bees. The second study aimed to determine the acute toxic effects of a range of pesticide adjuvants on adult honey bees. Adjuvants are considered “inert” under the EPA guidelines and therefore, do not undergo the same toxicity testing as pesticides. Primary research on the effects of pesticide adjuvants on honey bees is scarce and has focused on the organosilicone surfactant class of pesticide adjuvants. Adjuvants tested in this study included Dyne-Amic, Nu Film P, LI 700, Activator 90, Surf-90, Liberate, Choice Weather Master, and PHT Latron B-1956. Of the adjuvants tested, only Dyne-Amic was considered an organo-silicone surfactant. Other adjuvant types tested included non-ionic surfactants, penetrants, spreaders, stickers, wetters, antifoaming agents, deposition aids, acidifiers, drift control agents, and water conditioning agents. Results indicate that the pesticide adjuvants Dyne-Amic, Surf-90, and Liberate are acutely toxic to honey bees. Tank-mix combinations of pesticides and adjuvants demonstrate significantly increased toxicity over that of their constituents. These findings identify a potential explanation for honey bee losses around almond bloom, but further research is needed to fully understand the risk adjuvants pose to insect pollinators.
Reed Johnson (Advisor)
Guy Brock (Committee Member)
Roman Lanno (Committee Member)
Larry Phelan (Committee Member)
97 p.
Entomology; Environmental Science
Honey bee, Almonds, Insecticide, Fungicide, Pesticide, Pesticide Adjuvant, Spray Adjuvant, Adjuvant, Toxicity, Spray, Spray Toxicity, Potter Tower, Insect

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Citations

  • Walker, E. K. (2021). Assessment of toxicity of almond insecticide-fungicide-adjuvant treatments applied on adult honey bees at field relevant concentrations [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1618825948672527

    APA Style (7th edition)

  • Walker, Emily. Assessment of toxicity of almond insecticide-fungicide-adjuvant treatments applied on adult honey bees at field relevant concentrations. 2021. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1618825948672527.

    MLA Style (8th edition)

  • Walker, Emily. "Assessment of toxicity of almond insecticide-fungicide-adjuvant treatments applied on adult honey bees at field relevant concentrations." Master's thesis, Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1618825948672527

    Chicago Manual of Style (17th edition)

osu1618825948672527
451
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