In the heart of Brazil’s soybean fields, a silent war rages. The enemy? The nefarious stink bug, Euschistus heros, a pest that wreaks havoc on crops and costs farmers millions. But a new ally has emerged in this battle: a group of fungi from the Metarhizium family, which show promising potential to control these pesky invaders.
Aline Nunes-Silva, a researcher from the Department of Entomology and Acarology at the Escola Superior de Agricultura ‘Luiz de Queiroz’, University of São Paulo (ESALQ-USP), has been leading the charge against these stink bugs. Her latest study, published in the journal Biological Control (Control Biologicalo in English), explores the use of Metarhizium species as a biological control agent, offering a sustainable and eco-friendly solution to this agricultural menace.
The stink bug, E. heros, is no ordinary pest. It’s one of the most destructive species in soybean cultivation, causing significant yield losses. Traditional chemical pesticides have proven ineffective and environmentally harmful, driving the need for alternative solutions. This is where Metarhizium comes in.
Nunes-Silva and her team evaluated the susceptibility of E. heros to 15 different isolates of Metarhizium. The results were striking. Isolates of M. pingshaense, M. humberi, and M. robertsii showed a mortality rate of over 95% in just 8 days. “The high susceptibility of E. heros to these Metarhizium species is a significant finding,” Nunes-Silva explained. “It opens up new avenues for biological control of this pest.”
But the potential of these fungi doesn’t stop at high mortality rates. The study also found that certain isolates, like ESALQ 4395 and ESALQ 3364, have a high aerial conidia yield, similar to commercial isolates. This means they can be produced in large quantities, making them a viable option for large-scale agricultural use.
The average lethal concentration of these isolates was found to be around 5.1×105 conidia/mL for adult insects. Interestingly, the study did not observe age-dependent mortality, with adults showing more pronounced mortality than immature insects. This could be a game-changer for farmers, as adult stink bugs are often the most damaging.
The research also challenges the notion that stink bugs are resistant to entomopathogenic fungi due to the fungistatic and fungicidal action of their alarm pheromone. “Our data demonstrates that E. heros is highly susceptible to Metarhizium,” Nunes-Silva stated. “This is particularly true for species that are not commercially explored in Brazil, like M. humberi, M. pingshaense, and M. robertsii.”
So, what does this mean for the future of pest control? The potential is immense. These Metarhizium species could revolutionize the way we control stink bugs, offering a sustainable and effective alternative to chemical pesticides. This could lead to increased crop yields, reduced environmental impact, and significant cost savings for farmers.
Moreover, the success of these fungi in controlling stink bugs could pave the way for their use against other pests. The agricultural industry is always on the lookout for new, sustainable solutions, and Metarhizium could be the answer.
As Nunes-Silva puts it, “The future of pest control is biological. And Metarhizium is at the forefront of this revolution.” With further research and development, these fungi could shape the future of agriculture, making our farms more sustainable and our food more secure. The battle against the stink bug is far from over, but with allies like Metarhizium, farmers have a fighting chance.