Effectiveness of Varroa destructor mite control methods and some prospects for breeding honey bee populations resistant to it

To combat the mite Varroa destructor, identified by Anderson and Trueman (2000) as the most significant pathological threat to honey bees and the causative agent of the invasive disease varroatosis, various chemical, biological, and zootechnical control methods have been developed and proposed. However, no sufficiently effective protection methods currently exist against this mite. The widespread use of chemical control agents contributes to the accumulation of residual substances in bee products and becomes ineffective due to the development of acaricide resistance in mite populations. Additionally, chemical treatments reduce the selective pressure of natural selection, thereby hindering coevolutionary processes that establish stable parasite-host relationships. An alternative approach to reducing dependence on acaricides involves selectively increasing hereditary resistance or tolerance to the mite through breeding programs. Although this approach has achieved some success in practical breeding, it is labor-intensive and often depends on complex genetically determined behaviors that are difficult to phenotype. Research Objective: to conduct a comparative analysis of the effectiveness of physical (heat treatment) and chemical (acaricide "Bipin") methods for controlling V. destructor, considering their impact on the health of bee colonies and resistance to the mite. The study was conducted in the fall of 2022 at the apiaries of Denis Dmitriev and Alexander Moiseyev, located in the village of Strunino (59°30'03"N, 32°54'16"E) in Tikhvin district of Leningrad Oblast. For the physical method, worker bees were shaken from frames into a mesh container, weighed, and placed in a V.V. Yarankin thermal chamber (model YAV-79-09). Treatment involved exposure to hot air at 48°C for 15 min. After treatment, the bees were returned to their colonies, and the number of mites fallen to the bottom of the container was counted. For the chemical method, bees were treated with Bipin, condestructor taining 12.5% amitraz, following the manufacturer’s instructions. The working solution was applied along the hive “streets” at a rate of 10 ml per street. One week later, the number of mites fallen to the bottom of the hive was recorded. The degree of mite infestation, expressed as a percentage, was determined according to the guidelines for rapid diagnosis of varroatosis and assessment of mite infestation levels in apiary conditions, approved by the Main Veterinary Directorate of the Ministry of Agriculture of the USSR on January 16, 1984. In the first experiment, bee colonies were treated twice with Bipin (October 10 and 17, 2022) at weekly intervals. One week later (October 24, 2022), the same colonies underwent heat treatment. In the second experiment, the treatment order was reversed: colonies were first heat-treated, followed by two Bipin treatments. All counts and measurements were performed in triplicate. Chemical methods for controlling varroatosis using Bipin in the first experiment demonstrated high efficacy, particularly during the initial treatment (M = 1262.50 pcs, 5.48%), although there was considerable variability between colonies (CV = 166%). Physical control methods employing heat treatment in the second experiment were also effective (M = 479.00 pcs, 1.77%) and exhibited greater consistency between colonies (CV = 76%). Bipin treatment was more effective than heat treatment in the first experiment (p < 0.05), whereas heat treatment was more effective than Bipin in the second experiment (p < 0.001). However, the overall differences between Bipin and heat treatment were not statistically significant (p > 0.05), preventing a definitive conclusion regarding the superiority of either method. For practical application, a combined treatment approach is recommended: an initial Bipin treatment for rapid mite reduction, followed by heat treatment to maintain stable control of the residual mite population. For organic beekeeping, heat treatment alone is preferable, as it does not leave chemical residues. Effective varroatosis control in apiaries requires: initial treatment with Bipin for rapid mite infestation reduction; use of heat treatment as a primary or supplementary method for sustained control; monitoring mite infestation levels before and after treatments. When using Bipin, it is essential to adhere to recommended dosages (0.5 ml of 12.5% amitraz solution per 10 frames) and conduct treatments during periods of minimal bee activity (early spring or late autumn) to minimize stress. Compliance with regulations is necessary to reduce chemical residues in honey and wax. For heat treatment, equipment with precise temperature control (40-48°C) and exposure times (15-30 min) should be used. Treatments should be performed during the broodless period to maximize mite mortality while avoiding excessive heating to minimize adverse effects on adult bees and brood. Effective varroa-tosis management requires continuous monitoring and prevention, including regular diagnosis of mite infestation to determine optimal treatment timing, alternating chemical and physical methods to reduce the risk of mite resistance, and maintaining detailed treatment records. Additionally, efforts to develop Varroa-resistant honey bee populations exhibiting hygienic behavior through selective breeding are crucial. This approach will support sustainable beekeeping practices and contribute to preserving ecological balance and biodiversity. The article contains 2 Tables, 47References. The Authors declare no conflict of interest.

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