Shannon Brandon, Zhang Rui, Marsh Lucas, Johnson Reed M
Department of Entomology, The Ohio State University, Wooster, Ohio, United States of America.
Department of Statistics, The Ohio State University, Columbus, Ohio, United States of America.
PLoS One. 2025 Jun 17;20(6):e0320037. doi: 10.1371/journal.pone.0320037. eCollection 2025.
Beekeepers must manage Varroa destructor mites to maintain colony health. Large-scale beekeepers often use chemical treatments (miticides) to manage this pest. Miticide resistance drives a need for compounds with alternative modes of toxic action that can be used in rotation as part of a Varroa management plan. This research aimed to determine the efficacy of oxalic acid, clove oil, and fenpyroximate when delivered in glycerin soaked in strips and combined with a range of bee-safe adjuvants. Adjuvants are a group of compounds used in plant pesticide applications to increase the spreading and penetration of a pesticide. Laboratory cage trials tested a miticidal active ingredient (oxalic acid, clove oil, or fenpyroximate) and an adjuvant (Ecostep BC-12®, Ecostep SE-11®, Ecostep AE-13®, Ecostep CE-13®, or Silwet L-7500®) in glycerin-soaked strips. Field trials evaluated the best performing active ingredient-adjuvant combination from cage trials, oxalic acid combined with Ecostep BC-12® adjuvant in glycerin-soaked strips. Neither glycerin control, oxalic acid alone, or oxalic acid with adjuvant caused a significant change in Varroa per 100 bees in field trial year 1, when starting Varroa levels were high (average 11.8 Varroa per 100 bees across all treatment groups). In year 2, when starting Varroa levels were low (average 0.58 Varroa per 100 bees across all treatment groups), Varroa per 100 bees increased 2.6-fold for the glycerin control and 2.8-fold for oxalic acid alone, while a 29% reduction was observed in the oxalic acid with adjuvant treatment. Additionally, mite drop data indicated increased speed for the miticidal effect when an adjuvant is included with oxalic acid. This research informs formulation chemistries for oxalic acid and other miticides to help beekeepers maintain healthy hives.
养蜂人必须管控狄斯瓦螨以维持蜂群健康。大规模养蜂人通常使用化学处理方法（杀螨剂）来对付这种害虫。杀螨剂抗性促使人们需要具有替代毒性作用模式的化合物，以便作为狄斯瓦螨管理计划的一部分轮流使用。本研究旨在确定草酸、丁香油和唑螨酯在浸于甘油中的条带中递送并与一系列对蜜蜂安全的助剂结合时的功效。助剂是用于植物农药应用中的一组化合物，可增加农药的扩散和渗透。实验室笼养试验在浸于甘油中的条带中测试了一种杀螨活性成分（草酸、丁香油或唑螨酯）和一种助剂（Ecostep BC - 12®、Ecostep SE - 11®、Ecostep AE - 13®、Ecostep CE - 13®或Silwet L - 7500®）。田间试验评估了笼养试验中表现最佳的活性成分 - 助剂组合，即浸于甘油中的条带中的草酸与Ecostep BC - 12®助剂组合。在田间试验的第1年，当起始狄斯瓦螨水平较高时（所有处理组每100只蜜蜂平均有11.8只狄斯瓦螨），甘油对照、单独的草酸或含助剂的草酸均未导致每100只蜜蜂中的狄斯瓦螨数量发生显著变化。在第2年，当起始狄斯瓦螨水平较低时（所有处理组每100只蜜蜂平均有0.58只狄斯瓦螨），甘油对照的每100只蜜蜂中的狄斯瓦螨数量增加了2.6倍，单独草酸处理增加了2.8倍，而含助剂的草酸处理则减少了29%。此外，螨掉落数据表明，草酸与助剂一起使用时杀螨效果的速度加快。本研究为草酸和其他杀螨剂的配方化学提供了信息，以帮助养蜂人维持健康的蜂群。
