FEEDING MENTHOL TO HONEYBEES (HYMENOPTERA: APIDAE): ENTRY AND PERSISTENCE IN HAEMOLYMPH WITHOUT CAUSING MORTALITY

Tracheal mites, Acarapis woodi (Rennie) (Acari: Tarsonemidae), are important parasites of honeybees, Apis mellifera L. (Morse and Flottum 1997). They enter the prothoracic tracheae and feed through the walls on haemolymph. Currently, these mites are controlled by applying 50 g of menthol crystals in a perforated bag per hive when ambient temperatures are 15°C or more. Even then, it takes 2 weeks for the menthol to perfuse the hive (Herbert et al. 1988; Wilson et al. 1990). In cold climates, sublimation of menthol is too slow to be effective in controlling mites, especially in spring and fall when control is most needed (Scott-Dupree and Otis 1992).Because menthol fumes enter the bees' trachea and kill the mites therein, it may be possible to kill the mites with menthol that is delivered to them via the haemolymph. Therefore, finding if menthol could become systemic when ingested by bees and it could kill tracheal mites by that route, an ingestible menthol medicament for the bees would hold potential for mite control (Kevan and Kevan 1997).