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

Abstract

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®WP), Metarhizium anisopliae (Metarril®WP), and Cordyceps fumosorosea (Octane®SC) on Melipona quadrifasciata, Plebeia droryana, and Scaptotrigona bipunctata (Hymenoptera: Apidae). Direct contact with the concentration of 107 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®WP and Metarril®WP bioinsecticides were characterized as harmless to moderately harmful. Octane®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.