Application Methods for Bacillus thuringiensis Used to Control Larvae of the Greater Wax Moth (Lepidoptera: Pyralidae) on Stored Beeswax Combs

Abstract

Various methods for the application of Certan (Sandoz, San Diego, Calif.), a commercial formulation of Bacillus thuringiensis Berliner for control of the greater wax moth, Galleria mellonella (L.), were tested on beeswax combs. A viable B. thuringiensis spore assay was used to assess Certan distribution and deposition following treatment. A hand-held airless paint sprayer and a conventional machine sprayer proved satisfactory for applying Certan, although both required individual handling of each frame of comb to be treated. A dip treatment gave adequate B. thuringiensis coverage but was not deemed practical for use by beekeepers. Aerosol treatment did not give satisfactory deposition rates. Cold fogging of many frames at once within two enclosures gave uneven distribution but adequate deposition of B. thuringiensis spores. Thermal fogging within enclosures of two sizes resulted in uniform distribution and sufficient deposition under various conditions of fogging suspension volume and B. thuringiensis concentration. The use of an inert carrier in thermal fogger suspensions was essential for good coverage. Thus three methods (handheld airless spray, conventional spray, and thermal fog) proved successful and can be used by beekeepers. The method of choice will depend on the number of frames requiring treatment, the cost of labor required to treat them, and equipment costs.