The effectiveness of formic acid for the prevention and treatment of Tropilelapsosis in Apis mellifera L. colonies

In the context of widespread honey bee colony collapse, the search for highly effective tools for honey bee conservation is a pressing issue. The aim of the research was to develop a scheme for the application of formic acid (85 %) in Apis mellifera L. colonies affected by Tropilaelaps spp. The study of formic acid effectiveness was conducted in apiaries of the Krasnodar Region from May to August 2024 and in the Republic of Dagestan from June to August 2025. In each location, one control group and two experimental groups were formed, with 8 bee colonies in each. For the first time, the comparative effectiveness of formic acid application for Tropilaelapsosis in honey bees was studied using both the standard scheme (3 applications of evaporators with a 7-day interval) recommended for Varroosis and the experimental scheme (5 applications with a 4-day interval). The daily evaporation intensity of formic acid was determined. The effectiveness of formic acid was monitored by the degree of brood infestation with Tropilaelaps spp. mites before treatment and 25, 45, and 60 days after the start of treatment. It has been established that the evaporation intensity of formic acid at ambient temperatures of 16–27 °C ranges from 80 to 100 % within 3 days, resulting in a period within the bee colony's nest where the therapeutic effect of the preparation is absent. Considering the biological characteristics of Tropilaelaps spp. mites which are predominantly found in capped brood, individuals emerging from cells during this period do not die but resume reproduction. Therefore, it is necessary to use prolonged-action preparations. The application of formic acid in bee colonies at the initial stage of infestation with Tropilaelaps spp. significantly reduced the degree of capped brood infestation after 60 days by an average of 3.7 times using the standard varroosis treatment scheme and by 12.0 times using the studied scheme compared to the control group (P≤0.01). Formic acid, when used 5 times with a 4-day interval, compared to the standard application scheme, significantly reduced the degree of Tropilaelaps spp. infestation in capped brood in bee colonies after 60 days by 2.7–3.8 times (P≤0.01), with an effectiveness of 65–74 %.