Vurroa jacobsoni control by feeding honey bees with organic cupric salts

For three years, about 1,500 hives were surveyed for varroa mites following feeding tests using cupric gluconate and cupric lactate in sucrose syrup. Three to five litres per hive of 0 to 2.8g of copper metal per litre of sucrose syrup were given in spring and/or summer. Bee and mite mortalities were recorded up to four years without significant toxicity being noted for honeybees. By contrast, up to 91% of the mites were killed in a dose-dependent manner by gluconate. Lactate was markedly less active than the gluconate, although it also prevented reinfestations. Cupric gluconate in sugar syrup was as attractive, if not moreso, than pure sucrose, and the copper concentrations in honey at harvest were unchanged. Efficacy of treatments was not brood dependent. Cupric organic salts therefore provide a safe way for preventing the infestation of hives and the development of the mite