Evaluation of efficacy of formic acid and thermal remediation for management of Tropilaelaps and Varroa mites in central Thailand

Authors: SANKOVITZ, MADISON - University Of Colorado; STEINHAUSER, NATALIE - University Of Maryland; YEMOR, TANAWAT - Rajamangala University Of Technology; Cook, Steven; Evans, Jay; RAMSEY, SAMUEL - University Of Colorado

Submitted to: Journal of Apicultural Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/9/2024
Publication Date: 5/16/2025
Citation: Sankovitz, M., Steinhauser, N., Yemor, T., Cook, S.C., Evans, J.D., Ramsey, S. 2025. Evaluation of efficacy of formic acid and thermal remediation for management of Tropilaelaps and Varroa mites in central Thailand. Journal of Apicultural Research. 10. Article e2495393. https://doi.org/10.1080/00218839.2025.2495393.
DOI: https://doi.org/10.1080/00218839.2025.2495393

Interpretive Summary: In the U.S., the honey bee, Apis mellifera plays host to a number of parasites and pathogens, including Varroa destructor, harmful ectoparasitic mites that feed on both adult and pupal honey bees and reproduce under wax-capped brood cells. Varroa have become resistant to many of the conventional pesticides used for their control, but other methods, including biopesticides are still effective. Unfortunately, a potentially novel threat, parasitic mites in the genus, Tropilaelaps (Tropi mites), specifically T. mercedesae, may soon complicate the apicultural landscape heavily impacted by Varroa. It is unclear whether methods used to control Varroa mites may be effective against Tropi mites. In this study we investigated the efficacy of two applications of the biopesticide, formic acid, and a non-chemical treatment involving heat remediation technique for controlling populations of both Varroa and Tropi mites. Results revealed that both formic acid treatments immediately and substantially reduced mite populations, and worked to maintain very low levels of mites for three weeks post treatment. In contrast, the heat treatment more gradually reduced mite populations, and did not maintain mite populations at low levels, but rather a resurgence in mite numbers was observed two weeks post-treatment. The results gained from this study highlight the effectiveness of formic acid treatments against both Varroa and Tropi mites.

Technical Abstract: The western honey bee, Apis mellifera, faces a new threat from the spread of parasitic Tropilaelaps (Tropi) mites, specifically T. mercedesae, which adds additional complexity to an apicultural landscape heavily impacted by Varroa destructor. In this study conducted in central Thailand, we investigated the efficacy of two methods of applying formic acid and a thermal remediation technique in controlling Tropi mites and Varroa focusing our attention on the reproductive stage of the mites which is restricted to capped brood cells. Results revealed that both formic acid treatments (Formic Pro and liquid formic acid) demonstrated an immediate and substantial reduction in live Tropi and Varroa populations, maintaining near-zero levels for the 3 week duration of the study. In contrast, thermal remediation, employing heating pads, exhibited a more gradual decline, achieving an 85.42% reduction in Tropi mites and a 92.33% reduction in Varroa mites by week three. Notably, heat-treated colonies experienced an unexpected resurgence in mite populations during week two. The findings contribute valuable insights into potential strategies for mitigating the threat of Tropi mites and highlight the urgency of further research to safeguard global honey bee populations.