Susceptibility of Melipona scutellaris Latreille, 1811 (Hymenoptera: Apidae) to Beauveria bassiana (Bals.) Vuill

Entomopathogenic fungi are frequently used as an alternative method for insect pest control. However, only a few studies have focused on the effect of these fungi on bees and on the selectivity of fungi to beneficial organisms in agroecosystems. The objective of the present study was to assess the susceptibility of worker bees of the species Melipona scutellaris (locally known as "urucu") to the isolate (Biofungi 1) of the entomopathogenic fungus Beauveria bassiana. The experiment was carried through indirect contact between the fungal suspension and newly-emerged bees and topical application of the fungal suspension on the back of newly-emerged bees. The sampling design was completely randomized and comprised five treatments, which included four different concentrations of the fungus: 1 x 10 super(5), 1 x 10 super(6), 1 x 10 super(7), 1 x 10 super(8) conidia/ml, and a control composed of distilled water. Each treatment had five replicates. The mortality data were subjected to an analysis of variance and a probit regression analysis, which provided an estimate of the lethal dose to 50% of the population (LD sub(50)). The adjustment of the curves to the model was tested with a chi-squared test and differences between curves were tested with a test for parallelism. Beauveria bassiana was virulent to urucu bees, killing the bees at the lowest dose used. These findings may help minimize the impact of this entomopathogen and, therefore, contribute to the maintenance of natural populations of these insects.