Mites in hives increase the survival of bees – 05/11/2023 – Science

Mites found in stingless bee colonies favored the survival of up to 69% of larvae and 87% of young individuals of these insects in the presence of thiamethoxam, an insecticide widely used in Brazil and banned in the European Union, although exported here by European countries .

The results are from a study supported by FAPESP and published in the Scientific Reports magazine by researchers from the State of São Paulo (Unesp) and Federal of São Carlos (UFSCar) universities.

In trials where there was no exposure to insecticides, survival was up to 96% when mites were present and between 24% and 63% without mites. In general, the study points out that the presence of small arachnids of the species Proctotydaeus (Neotydeolus) alveariispecialists in stingless bee hives, increases larval survival by about two times (2.3 times without the insecticide and 1.9 times with the substance).

The conclusions pave the way for the creation of biological solutions to prevent the death of bees, in addition to contributing to future tests to measure the effect of pesticides on stingless species.

“In the beginning, we didn’t even know if the mites were good or bad for the bees. There were no studies about it. Now, we have shown that they help the bees both by eating fungi, which would probably overgrow and suffocate them, and by serving as food for the bees. larvae”, explains Annelise Rosa-Fontana, who carried out the work during her postdoctoral studies at Unesp’s Institute of Biosciences (IB), in Rio Claro, with a grant from Fapesp.

“When the mites were present, both in the tests with and without insecticides, we could also observe that the bees developed better. The heads and bodies were significantly larger than in situations without mites”, says Adna Dorigo, who shares with Rosa- Fontana was the first author of the work, part of his master’s and doctorate at IB-Unesp.

When they reach the end of their life cycle, it is likely that the mites serve as a source of protein for the larvae. In the last days of the larval stage, the researchers noticed that there were no more mites in the in vitro tests, only eggs. Which suggests that the adults are eaten by bee larvae.

Before they are found in bee colonies Scaptotrigona postica, the analyzed mites had been registered in colonies of other stingless bees. Described in 1985, the species is totally dependent on this environment, just as other mites can specialize in the most different niches (read more here).

risk protocols

The analyzed bees have been studied to be included in insecticide toxicity tests in the Neotropical region, which includes Brazil. These tests are mandatory for the approval of the use of substances in agriculture by Ibama (Brazilian Institute for the Environment and Renewable Natural Resources).

The tests currently carried out, however, have as a model species the Apis mellifera, European bee introduced in the country. The Brazilian territory, however, is home to around 3,000 native species of bees, around 300 of which are stingless.

Bees are important pollinators for both native plants and agriculture and may die or be unable to return to the nest when exposed to pesticides (read more at: agencia.fapesp.br/39896 and agencia.fapesp.br/38636).

Understanding the relationship between different crops, pesticides and these insects is the theme of the project “Bee-agriculture interactions: prospects for sustainable use”, funded by FAPESP and coordinated by Osmar Malaspina, professor at IB-Unesp.

The project also has among its main researchers Roberta Nocelli, a professor at the Center for Agricultural Sciences (CCA) at UFSCar and co-author of the work published now, one of many achievements within the scope of the project.

“Our laboratory plays a fundamental role in establishing risk protocols that can support public policies. Bees are essential for ecosystems and for agricultural activity, which is why everyone’s focus must be on the conservation of these insects”, says Malaspina , who coordinated the study.

For the researcher, the work also contributes to thinking about solutions based on nature. Products generated from the research could either be distributed free of charge to meliponicultores, honey producers from the creation of stingless bees, or developed into small innovative companies.

All this without counting the training of specialized human resources. Rosa-Fontana is currently a researcher at the Complutense University of Madrid. In February, she was awarded funding from the European Marie Sklodowska-Curie Actions Postdoctoral Fellowship program, one of the most competitive and most prestigious in the world.

The award consists of an aid of 172 thousand euros (R$ 934.1 thousand) to be applied in his research on molecular tools in risk assessment of pesticides in European bees.

Dorigo, in turn, as soon as she finished her doctorate at IB-Unesp, she was hired by the company Eurofins Agroscience Services, one of the largest in the world in carrying out toxicological studies for the evaluation of pesticides. Currently, she is a researcher and acts as director of studies, where she continues to carry out research in the area.

The article Fungivorous mites enhance the survivalship and development of stingless bees even when exposed to pesticides is available here.