Submitted to: American Bee Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 13, 2000
Publication Date: N/A
Interpretive Summary: Synthetic chemical pesticides have been used for approximately 10 years to control the varroa mite, a serious pest of honey bees. Each synthetic pesticide has had problems associated with its use, from resistance to human toxicity concerns. We therefore initiated the present study to check the anti-varroa activity of natural "liquid smoke" compounds. Both compounds were effective in causing varroa mites to drop infested adult honey bees directly exposed to either compound. Application of these materials in a bee operation would probably require complete coverage of adults within the hive. Such a requirement would probably make these compounds more suitable for the small beekeepers, due to the high amount of labor that would be needed.
The varroa mite, Varroa jacobsoni Oud., is the most serious ectoparasitic pest affecting honey bees, Apis mellifera L., on a worldwide basis. In the present study, we investigated the activity of two preparations of smoke extract, both an experimental and a commercial preperation. In the first bioassay, which tested the activity of volatiles in dislodging varroa from infested adult bees, the experimental preparation caused significantly mor varroa drop than the corresponding control; the volatiles from the commercial preperation did not cause significantly more varroa drop than the corresponding control; the volatiles from the commercial preparation did not cause significant varroa drop. In the second bioassay, which measured varroa drop from infested bees sprayed directly with aqueous solutions of both smoke types, significant varroa drop was caused by direct contact to both the commercial and experimental samples. Analysis of both preparations by gas chromatography/mass spectrometry (GC/MS) revealed both preparations contained the phenolic compound 2, 6-dimethoxyphenol. Bioassay of direct exposure by this compound showed significant contact activity in causing varroa to dislodge from adult honey bees.