Microencapsulated medicines for beneficial insects

Few veterinary medicines are used for treating invertebrate micro-livestock. We made and tested a specially designed microcapsulated medicament that disguised, antifeedant properties of active ingredients and were of appropriate, ingestable sizes to enter the alimentary tracts where the active ingredient was liberated. Menthol is a fumigant used to suppress populations of parasitic tracheal mites in honeybee hives. Mentholated microcapsules, similar in size to pollen, were designed to deliver and liberate menthol into the bees' ventriculus (mid-gut) where it would be transported to the hemolymph (blood) and circulated. MEM (menthol doubly-microencapsulated with zein and stearic acid) was fed in sugar-candy patties to honeybees without the menthol having its usual anti-feedant and irritant effects. In the laboratory, honeybees fed MEM ad libitum in sugar candy patties at menthol concentrations of 5 to 40 mg/g for two days showed about 40% higher mite mortality than did controls (fed sugar candy patty alone). In a commercially operated apiary, feeding a dose of 40 and 80 mg/g MEM in candy patties to colonies 4 times over 1.5 months, kept tracheal mite prevalence significantly below that in controls for at least 4 months. Our technology probably has wider applicability for disease treatment in micro-livestock used directly for food or fiber, and possibly in biocontrol.