The ‘super pest’ Colorado potato beetle has the genetic resources to avoid our attacks

The Colorado potato beetle has developed resistance to over 50 different types of insecticides, making the insect a “super pest” wreaking havoc on potatoes worldwide.

New research reveals that the beetle achieved this feat largely by tapping into a deep pool of diversity within its genome, which allowed different populations across the United States to rapidly develop resistance to almost anything. what the humans threw at him.

The pest’s rich diversity and existing arsenal of resistance genes will likely make it difficult to control in the future, no matter what new insecticides researchers develop. But the new understanding of the pest’s genomic resources could help scientists design management systems that control it.

“This beetle was one of the first to be attacked with chemicals in the modern era, and it has been very successful in evolving beyond those attacks,” says Sean Schoville, professor of entomology at the University of Wisconsin-Madison who led the new analysis. “For other insects we hope to control, there are lessons to be learned from studying this pest. What mechanisms does this insect use to get past these insecticides?”

Along with his collaborators at UW-Madison and other institutions, Schoville published his findings Jan. 19 in the journal Molecular biology and evolution.

Schoville’s team first sequenced the Colorado potato beetle’s genome in 2018. Since then, they’ve been probing the genome to figure out how the insect can overcome new insecticides as quickly as it does. To do this, they sequenced several dozen beetles from across the United States. These regional populations vary in what pesticides they are resistant to and where they come from, which can give clues to the evolutionary history of the pest.

Scientists found that these different regional groups were changing so rapidly because their parent populations already possessed the genetic resources to defeat insecticides.

“Genes that evolve are well known to be involved in insect resistance. But what’s interesting is that different populations change different parts of genes or different genes in the same way,” says Schoville. This similar, but not identical, pathway to resistance in different populations is known as repeated evolution.

This rapid evolution based on the wealth of existing genetic diversity is at odds with an older evolutionary model which assumed that rare mutations should appear slowly in a population. While new mutations are developing that may contribute to insecticide resistance, the Colorado potato beetle’s rapid response to new chemicals in different parts of the country can only be explained by its existing diversity.

The results are bad news for farmers and scientists hoping to reverse the trend of Colorado potato beetle attacks. It seems unlikely, says Schoville, that even a brand new insecticide can control the pest for long.

But armed with knowledge of how the Colorado potato beetle evaded our attacks, future research could help produce creative strategies to keep pace with this enemy.

“More sophisticated models could help us understand how different management techniques affect the evolution of the beetle. This could allow us to change our management style to slow it down,” says Schoville.

This work was supported in part by the US Department of Agriculture (grants 2015-67030-23495 and 58-5090-7-073) and two Hatch Awards (grants WIS02004 and VT-H02010).

Source of the story:

Material provided by The University of Wisconsin-Madison. Original written by Eric Hamilton. Note: Content may be edited for style and length.

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