A new study by Brazilian biologists suggests that the effect of pesticides on bees could be worse than previously thought. Even when used at a level considered nonlethal, an insecticide curtailed the lives of bees by up to 50%. The researchers also found that a fungicide deemed safe for bees altered the behavior of workers and made them lethargic, potentially jeopardizing the survival of the entire colony.
The results of the study are published in Scientific Reports, an online journal owned by Springer Nature. The principal investigator was Elaine Cristina Mathias da Silva Zacarin, a professor at the Federal University of São Carlos (UFSCar) in Sorocaba, São Paulo State, Brazil. Researchers affiliated with São Paulo State University (UNESP) and the University of São Paulo’s Luiz de Queiroz College of Agriculture (ESALQ-USP) also took part in the study.
The São Paulo Research Foundation – FAPESP supported the research under the aegis of the Thematic Project “Bee-agriculture interactions: perspectives on sustainable use“, for which the principal investigator is Osmar Malaspina, a professor at UNESP in Rio Claro campus. Funding was also provided by the Brazilian government via CAPES, the higher education research council, and by the Sorocaba Beekeepers’ Cooperative (COAPIS).
It is a well-known fact that several bee species are disappearing worldwide. The phenomenon has been observed since 2000 in Europe and the United States and since at least 2005 in Brazil.
In Rio Grande do Sul, Brazil’s southernmost state, the loss of some 5,000 colonies, corresponding to 400 million bees, was reported between December 2018 and January 2019.
One of the most widely affected species is Apis mellifera, the Western honeybee, which is of European origin and the source of most commercially available honey.
Hundreds of wild native Brazilian species may also be affected in the natural environment. The economic impact is estimated to be huge, as most agricultural crops depend on pollination by bees. All kinds of edible fruit are just one clear example.
The reason for this sudden mass disappearance is also well known: it is the indiscriminate and improper application of agrochemicals, such as insecticides, fungicides, herbicides and acaricides. Bees are contaminated when out of the hive and bring the toxic chemicals back with them on their return. Inside the nest, the chemicals are ingested by larvae, shortening their lives and impairing the functioning of the entire colony.
“Soybean, corn and sugarcane monocultures in Brazil depend on the intensive use of insecticide. Bee colonies are contaminated, for example, if farmers fail to comply with the recommended minimum safety margin of 250 m between a crop and the surrounding forest…