Effect of entomopathogenic fungus-formulated bioinsecticides on stingless bees (Hymenoptera: Apidae: Meliponini) in the laboratory

Stingless bees are of environmental and economic importance because they pollinate plants of agricultural and native interest. During foraging, bees can come into contact with synthetic insecticides, resulting in lethal and sublethal effects. Biological control using entomopathogenic fungi (EF) is an alternative to the use of synthetic insecticides. However, despite promising results in pest control, gaps in the activity of EF on nontarget organisms, such as stingless bees, have not been completely recognized. Thus, this work aimed to evaluate the effects of three bioinsecticides formulated from Beauveria bassiana (Boveril(& REG;)WP), Metarhizium anisopliae (Metarril(& REG;)WP), and Cordyceps fumosorosea (Octane(& REG;)SC) on Melipona quadrifasciata, Plebeia droryana, and Scaptotrigona bipunctata (Hymenoptera: Apidae). Direct contact with the concentration of 10(7) conidia.mL(-1) indicated a differentiated tolerance between bee species, as well as significant differences in mortality caused by these bioinsecticides. Melipona quadrifasciata showed the lowest tolerance to bioinsecticides, while S. bipunctata had the lowest mortality. According to the classification proposed by the International Organization for Biological Control, the Boveril(& REG;)WP and Metarril(& REG;)WP bioinsecticides were characterized as harmless to moderately harmful. Octane(& REG;)SC caused mortality between 74.7 and 95% and was thus characterized as harmful to all three studied species. Although these bioinsecticides are selective for nontarget organisms, it is evident that the toxicity for stingless bees is dependent on the EF species used. Thus, its use must be carried out according to criteria that minimize damage to bees, effectively resulting in the development of sustainable agriculture.

Automated summary

Stingless bees are important for pollination, but they can be affected by synthetic insecticides. This study evaluated the effects of three bioinsecticides on different stingless bee species. The results showed variation in tolerance and mortality among the bee species. The bioinsecticides were classified as harmless to moderately harmful, but Octane(& REG;)SC was found to be harmful to all three species. It is important to use these bioinsecticides with criteria that minimize harm to bees and promote sustainable agriculture.