Brazilian, US researchers develop use of fungus to control pasture ticks

By Leonardo Gottems, Reporter for AgroPages

A team of researchers from Brazil and the United States (US) developed a method for controlling the tick, Rhipicephalus microplus, through an innovative strategy, which is a fungus applied to pastures.

For the first time, dry granular formulations of the fungus, Metarhizium robertsii, were applied to the soil to suppress the parasite, which attacks cattle in Brazil.

The strategy achieved a relative effectiveness of at least 64.8% during the wetter season, reducing the need to use chemical acaricides on animals. The idea was based on the fact that 95% of the tick population is located on pastures, not on animals.

The innovative approach was developed by researchers from Embrapa, the Federal University of Goiás (UFG), the Federal Rural University of Rio de Janeiro (UFRRJ) and the American company, Jaronski Mycological Consulting. Their results were recently published in the journal, Scientific Reports, of the Nature Group.

Éverton Kort Kamp Fernandes from UFG explained that biological control using entomopathogenic fungi has been widely explored in agriculture for controlling arthropod-pests. “In this sense, the application of the bioproduct can be planned in two distinct and complementary ways, which are directly on the infested animal or on the pasture, or both, effectively controlling ticks at various stages of development,” he said.

Alan Marciano from UFRRJ stated, “The use of these formulations, combined with other control strategies, will help producers ensure less infested animals and reduce the pressure of tick resistance to chemical acaricides, enabling the production of quality milk and meat from healthier animals free of uncontrolled infestations.”

The study also detected the persistence of the fungus in the soil and the fungal colonization of the roots of grasses cultivated in pastures, ensuring long-lasting results with a reduced need for new applications. The researchers also noted that the fungus could be incorporated in the maintenance and formation of pastures, depending on future studies.

Brazil has the largest number of commercial cattle herds in the world, totaling more than 200 million heads, and the tick is the main pathogen vector in these animals. According to a study published in the Brazilian Journal of Veterinary Parasitology, which provided data on the total number of animals at risk from parasites in the country, the cattle tick is responsible for economic losses of some US$3.2 billion per year.

Over time, an increase in pest resistance to chemical acaricides was observed. The ticks are also a vector for pathogens and their parasitism causes anemia as they feed on blood. In addition, they damage the scalp of cattle, predisposing the animals to secondary infections and myiasis, therefore, causing stress and reducing productivity.