Toxicological assessments of lethal and sublethal effects caused by exposure to agrochemicals in stingless bees (APIDAE, Meliponini)
Authors:   , Botina Jojoa Lorena Lisbetd 
Published: February 2024

Brazil has a wide diversity of species of stingless bees of the tribe Meliponini, with 244 described species. In the last decade, after a reported decline in bees’ colonies, stingless bees have been used as a study model in toxicological assessments in the tropical regions. These assessments consider mainly the risks associated with exposure to agrochemicals, which can affect the health of these essential pollinators and consequently compromise their ecosystem services. The present study aimed (a) to review the literature considering the toxicological assessments of agrochemicals in stingless bees in Brazil, (b) to provide a big picture considering the scenario and the trends of research on bees and their interaction with agrochemicals in the last 76 years, including species, methods of exposure and tested agrochemicals, (c) to provide adapted protocols for carrying out toxicological assessments in stingless bees; and (d) to assess the lethal and sublethal effects of larval exposure on the stingless bee Partamona helleri to different agrochemicals. Data from the literature review and meta-analysis (implementing artificial intelligence) underwent identification, screening, eligibility and inclusion phases, and toxicological assessments with agrochemicals were analyzed according to exposure via and development stage. The number of studies considering the exposure of stingless bees to agrochemicals, particularly insecticides, has increased over the last decade. However, these studies cover only 2.9% of the stingless bee species in Brazil. Toxicological assessments of agrochemicals on pollinators mainly comprise the order Hymenoptera (Apidae), on emphasis Apis mellifera. The group of insecticides, especially neonicotinoids, were the most studied in bees and the main route of exposure used was acute and under laboratory conditions. The protocols described here were successfully validated, exhibiting a high survival rate between 80 – 100% of the control treatment via chronic exposure in larvae and via acute exposure in adults, respectively, which is necessary to satisfy regulatory authorities. The survival rate of larvae orally treated with three agrochemicals was affected, according to dose and type of compound, and the recommended field doses of copper sulfate (CuSO4), and spinosad were highly toxic, unlike glyphosate. Locomotion was altered in adults derived from treated larvae, and the gut microbiota composition did not change by agrochemical. It can conclude that the systematic reviews, the description of the methods of toxicological assessments and exposure to agrochemicals assessing the possible lethal and sublethal effects on stingless bees described here can improve the knowledge regarding the role that agrochemicals play in the decline of stingless bees, as well as point out the gaps that need to be filled. In this way, the data obtained provide a comprehensive overview of the risks that these pollinators may be suffering because of human activities. Keywords: Behavior. Gut microbiota. Risk assessment. Systematic review. Wild bees.