In July 2023, more than 100 million bees were found dead in the state of Mato Grosso, Brazil. It is also estimated that c. 600 beehives, containing a total of 170,000–200,000 bees, were poisoned in apiaries in the cities of Sorriso, Sinop and Ipiranga do Norte. The results of analyses carried out by the Institute of Agricultural Defence of Mato Grosso indicate that the pesticide Fipronil was the cause.

The use of this broad-spectrum insecticide is allowed in Brazil, but aerial spraying of it has been prohibited since 2012 by the Brazilian Environmental Licensing Agency (IBAMA). The toxicity of this product for bees and its illegal application by aerial spraying, with the action of wind amplifying the impacts, are the main causes of the high mortality. The farmer responsible was fined BRL 225,000 (c. USD 47,000).

Bees are essential for pollinating both agricultural crops and native plants. Four threatened bee species were found to have been affected by the misuse of the pesticide. However, the impact on bee assemblages is likely to have been even greater given that a single study recently recorded the presence of 134 species in areas of native habitat and adjacent soybean crops across agricultural landscapes in Mato Grosso (Ferreira et al., 2022, Agriculture, Ecosystems and Environment, 338, 15, 108084).

In addition to the environmental impacts on fauna and flora, beekeepers will lose significant income. Pollination services for food in Brazil have been valued at USD 45 billion annually (Giannini et al., 2015, Journal of Economic Entomology, 108, 3, 849). There is a need for new guidelines and regulations for the use of pesticides in Brazil, as in the last 4 years more than 2,000 substances have been approved for use in agriculture and industry. In addition, Brazil needs to strengthen the inspection process for the commercialization and use of pesticides, especially in Mato Grosso, an important state for agricultural production that encompasses three megadiverse biomes: the Pantanal, Cerrado and Amazonia.