PESTICIDAL PESTS | They discover a new species of worm that can protect crops without pesticides

The pesticides are used in the agriculture to control weeds, insect infestation and diseases. There are many different types of pesticides and each one is used to combat specific pests. But The use of pesticides is not harmless: they can cause serious damage to the environment, flora, fauna and humans..

The main long-term effects of pesticides can be grouped into: those that directly affect the exposed individual, such as sterility, aplastic anemia, cancer and various disorders; and those that are observed in his descendants, as teratogenesis, mutagenesis, alterations of the immune system or nervous system.

For this reason, scientists have been researching for decades methods that help avoid the use of pesticides. These methods to control pests, diseases and weeds include: biologicalwhich consist of use living organisms in order to control populations of another organism.

Entomopathogenic nematode worms parasitize insects and they have been used for a long time in biological control programs against insect pests in agriculture. The nematodes of the Steinernema family, discovered a century ago, They are not harmful to humans or other mammals.

Some nematode species have a wide host range, such as Steinernema carpocapsaewhich can infect about 200 insects, while others have a specific host range, such as Steinernema scapterisciwhich is adapted to infect insects only within the order Orthoptera.

UCR nematologist Adler Dillman and his colleagues in their laboratory. Stan Lim/UCR

In laboratory tests, nematodes can have a guest range wider than normal that does not transfer to the field. However, species that are in a natural environment are well adapted to those environmental conditions and are effective against existing pests.

Biological control agents

Scientists at the University of California Riverside (UCR) have discovered a new species of wormwhich they have called Steinernema also, which also infects and kills insects. With the particularity that These small worms could control crop pests in hot and humid places where other beneficial nematodes cannot currently thrive.

The guest range of steinernema adamsi has not yet been explored, so future studies should focus on that aspect to identify potential hosts and thus improve effectiveness in biological control.

One thing is clear: steinernema adamsi kill insects. The researchers confirmed this by putting some of these nematodes in containers with moths. “They were killed in two days with a very low dose of worms,” ​​Dillman recalls. As they are members of a genus that can infect hundreds of insects, researchers are confident that it will be “very beneficial”, whether it is a parasite specialist either generalist.

In the future, researchers hope to discover the unique properties of this nematode. “We still don’t know if it can resist heat, ultraviolet light or dryness. Nor do we know the variety of insects it is capable of infecting,” says Dillman.

Specimens of the new species of nematode. Adler Dillman/UCR

The discovery of this new species has important implications for the development of effective biological control agents in Thailand and in areas with similar weather conditions.

“Although there are more than 100 species of Steinernema, we are always looking for new species because each one has unique characteristics. Some might be better in certain climates or with certain insects,” says nematologist Adler Dillman, whose laboratory made the discovery.

“Our work contributes to our understanding of the diversity and evolution of entomopathogenic nematodes,” say the authors of the study, which has just been published in the Journal of Parasitology.

Almost invisible to the naked eye

The discovery was serendipitous: Dillman’s lab had requested samples of Steinernema, and DNA analysis revealed that they were not the species they had requested. “Genetically, they were unlike anything that had ever been described,” Dillman explains.

The worms of the newly discovered species are almost invisible to the naked eye, about half the width of a human hair and just under a millimeter long. “Several thousand in a flask looks like powdery water,” notes Dillman.

The discoverers have named the new species steinernema adamsi in honor of the American biologist Byron Adams, chairman of the Department of Biology at Brigham Young University. “Adams has helped refine our understanding of nematode species and their important role in soil ecology and nutrient recycling,” says Dillman. “I thought it was a fitting tribute to him,” she adds.

Adams, who is currently researching nematodes in Antarctica, is honored that such a “cool” species bears his name in scientific literature. Even more so because The biology of this animal is “absolutely fascinating”he comments.

“Apart from its obvious applications to alleviate human suffering caused by insects and pests, it also has much to teach us about the ecological and evolutionary processes involved in the complex relationships between parasites, pathogens, their hosts and their environmental microbiomes,” he notes.

“It’s exciting because Discovery adds another ‘insecticide’ that could teach us interesting new biology. They also come from a warm, humid climate, which could make them a good insect parasite in environments where currently commercially available orchard nematodes have not been able to flourish,” Dillman concludes.

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