Beauveria bassiana pathogenicity to the citrus rust mite Phyllocoptruta oleivora.

The pathogenicity of Beauveria bassiana to one of the major pests of citrus crops, Phyllocoptruta oleivora, was assessed by inoculating mites with different concentrations of conidia (1×106, 5×106, 1×107, 5×107 and 1×108). Treated mites were kept at controlled conditions (25 ± 0.5°C, 12 h photoperiod and 98% relative humidity) and mite survivorship was evaluated daily. Mortality was found to increase in time and was dependent on the conidia concentration, with values ranging from 24 to 91% for the lowest and highest conidia concentration, respectively. The calculated LC50 on the fifth day was 4.23×106 conidia/ml. Mean lethal time was 3.98, 9.79, 3.09 and 2.74 days for 5×106, 1×107, 5×107 and 1×108 conidia/ml, respectively. Conidia were found to adhere all over the mite body surface, especially at the anal region, where vegetative mycelium was found entering the mite body. We noticed the formation of small crystals inside the mite’s body that were produced during colonization of the body cavity by the fungus. This is the first report of B. bassiana pathogenicity for this species.