Formic acid fumigator for controlling varroa mites in honey bee hives

Division of Plant and Soil Sciences, Agricultural Sciences Buildinng, West Virginia University, P.O. Box 6108, G-168, 26506-6108, Morgantown, WV, USA
International Journal of Acarology (Impact Factor: 0.95). 06/2006; 32(2). DOI: 10.1080/01647950608684452


The 50% formic acid fumigator (FAF) for varroa mite control was developed as part of a SARE grant (1999 to 2001). The fumigator was evaluated for five years on 123 colonies in five bee yards in Connecticut, Maryland and West Virginia. Treatments eliminated all mites on adult bees and 90 to 95% of mites in sealed brood cells. Very few brood or new young adult bees were injured by the treatment. The fumigator is a simple design and the overall cost of treatment is about $1.00 per hive or less. The 50% FAF was less toxic to bees compared to other treatments using 65%. 80% or 90 % formic acid (FA). The fumigator was applied for 18-24 hours, when ambient temperatures were between 10-30° C. In the USA, one treatment in mid-August to mid-September was effective and usually all that was required each year. The 50% FAF used with other essential oil treatments including salt-grease patties with wintergreen, feeding 1:1 syrup with Honey-B-Healthy7 (spearmint and lemongrass essential oils), and use of screened bottom boards together provide a synergistic effect to keep mite numbers at a relatively low level, as part of an integrated pest management (IPM) system.

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Available from: Jim Amrine, Dec 03, 2014
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    • "n 70% ethanol as voucher specimens . Counts of live and dead varroa mites , in all stages , were recorded ; mites that showed any movement of legs or tarsi were counted as live . We sampled capped drone cells since varroa mites are more abundant in drone brood ( Ellis and Baxdale , 1994 ; Martin , 1997 ) . Also , Van Engelsdorp ( 2005 ) , in his 4 Amrine et al . 2007 Table 1 . August 15 , 2006 treatments west of Cocoa , Florida . Ten hives treated with 90 ml 50% formic acid + 15 ml HBH . Mite counts were made from 100 capped drone cells per hive on August 16 , 2006 ."
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    ABSTRACT: We used the 50% formic acid fumigator to treat 51 honey bee colonies in Florida on April 2, August 16 and October 23, 2006 and January 2, 2007, to control varroa mites. Treatments consisted of 90 to 110 ml of 50% formic acid mixed with 15 ml of Honey-B-Healthy™ essential oil concentrate to prevent queen losses. The fumigator was applied during daylight hours to each hive, screened bottoms were covered, openings taped over, and the entrance reduced to 3/8" by 3 1/2" (0.95 cm x 8.9 cm) and removed the next day after from 17 to 23.3 hours. Average mortality of varroa mites in capped drone cells was 93% (92.8% to 98.8%) (after adjustment for Abbott's correction for control mortality). Capped drone cells in old black comb had the lowest mortalities (66% to 84%): less of the 50% formic acid vapor was able to penetrate the thicker cappings.
    Full-text · Article · Jun 2007 · International Journal of Acarology
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    ABSTRACT: Controlling populations of varroa mites is crucial for the survival of the beekeeping industry. Many treatments exist, and all are designed to kill mites on adult bees. Because the majority of mites are found under capped brood, most treatments are designed to deliver active ingredients over an extended period to control mites on adult bees, as developing bees and mites emerge. In this study, a 17-h application of 50% formic acid effectively killed mites in capped worker brood and on adult bees without harming queens or uncapped brood. Neither acetic acid nor a combined treatment of formic and acetic acids applied to the West Virginia formic acid fumigator was as effective as formic acid alone in controlling varroa mites. In addition, none of the treatments tested in late summer had an effect on the late-season prevalence of deformed wing virus. The short-term formic acid treatment killed > 60% of varroa mites in capped worker brood; thus, it is a promising tool for beekeepers, especially when such treatments are necessary during the nectar flow.
    Full-text · Article · Apr 2008 · Journal of Economic Entomology
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    ABSTRACT: With the recent decline of honey bees, Apis mellifera (L.) (Hymenoptera: Apidae), there is a need for alternative or supplemental crop pollinators, such as Osmia cornifrons (Radoszkowski) (Hymenoptera: Megachilidae). However, O. cornifrons propagation could be impeded by a cleptoparasitic mite, Chaetodactylus krombeini Baker. We investigated the effects of formic acid and wintergreen oil on mortality of C. krombeini hypopi and O. cornifrons adults by determining the lethal concentration of each compound on each species. On average, >4.8 and >1.8 h were required to cause mortality in O. cornifrons adults when <2,473.5 ppm of formic acid and wintergreen oil was applied as a fumigant, respectively. When the two chemicals were directly applied to the exoskeleton of O. cornifrons adults, 353.4 ppm of wintergreen oil caused bee mortality within 10 min; however, no mortality was found with any formic acid application attempted. Mortality of C. krombeini hypopi occurred 5 and 10 min after application of >176.7 ppm of formic acid and wintergreen oil, respectively. Estimates of LC50 for C. krombeini hypopi treated with formic acid and wintergreen oil were 54.3 and 271.3 ppm, respectively. This study showed that C. krombeini could be controlled effectively without inducing O. cornifrons adult mortality based on concentration and duration of fumigation.
    Full-text · Article · Dec 2009 · Journal of Economic Entomology
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