Experimental Chemical Controls for Varroa Destructor in the European Honey Bee, Apis Mellifera

Emily Dawn Rendleman

doi:10.7273/000004478

Pollination is an essential part of the global agricultural system, and in the current state of monoculture-focused agriculture there is one pollinator that serves as a stanchion: the European honey bee, Apis mellifera. Despite their success, honey bee life is not always sweet. Honey bees are affected by four general classes of hazard known as the four “P’s”: poor nutrition, pesticides, pathogens, and parasites. The most cited cause of honey bee mortality is the parasitic mite Varroa destructor, and in this forty-eight colony miticide study an experimental stabilized 18.4% oxalic acid strip and a novel 6.5% amitraz strip were compared to a commercially available 3.3% amitraz strip and a 10.25% tau-fluvalinate strip. Treatments were applied on September 5th, 2021, and removed sixty days later, at which point a secondary chemical treatment was applied to “flush out” residual Varroa populations. Mite levels were assessed through sticky card captures and alcohol washes. Results showed that the mean mite drop in the three-day period after initial treatment application was significantly higher for hives treated with the experimental stabilized 18.4% oxalic acid strips (121.5±21.7) than those treated with 10.25% tau-fluvalinate strips (30.7±21.7, p=0.018). The same period showed no significant difference of mean mite drop between hives treated with the experimental stabilized 18.4% oxalic acid strip and either the commercial 3.3% amitraz strip (81.71±21.7) or novel 6.5 % amitraz strip (74.7±21.7). At the 60-day mark, when secondary treatments were applied, average mite drop per day for hives treated with experimental stabilized 18.4% oxalic acid strips (11.7±21.7) was significantly lower than the commercial 3.3% amitraz (265.0±21.7), novel 6.5 % amitraz (288.8±21.7), and 10.25% tau-fluvalinate (415.0±23.2) treated hives (p=<0.0001). Alcohol wash data supported these findings, with stabilized experimental 18.4% oxalic acid strip treated hives having significantly lower mean mites per 100 bees (0.3±0.9) than novel 6.5% amitraz (5.2±0.9), commercial 3.3% amitraz (5.6±0.9), and 10.25% tau-fluvalinate (10.7±0.9) treated hives. These findings demonstrated the effectiveness of a novel method of mite treatment utilizing a previously established chemical in the form of the stabilized 18.4% oxalic acid strip. Continued development of this strip can lead to improvements in Varroa mite management and benefits to beekeepers.

Experimental Chemical Controls for Varroa Destructor in the European Honey Bee, Apis Mellifera

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