Exterminators keep getting calls for one reason or the other. Wood-eating insects, such as beetles, termites and carpenter ants, are constantly chewing up walls or infesting trees and causing them to break down. The fight against these insects usually involves harmful pesticides; But now, at least some of them can be eliminated by using a certain species of fungus.
Bark beetle infestations are the bane of spruce trees. Eurasian spruce bark beetle (IPS Typographus) The bark contains high amounts of phenolic compounds, organic molecules that often act as antioxidants and antimicrobials. They protect spruce bark from pathogenic fungi – and the beetles reap the benefits. Their bodies increase the antimicrobial power of these compounds by converting them into substances that are even more toxic to the fungus. This appears to make the beetles impervious to the fungus.
However, there is a way to overcome the beetles’ borrowed defenses. Led by biochemist Ruo Sun, a team of researchers at the Max Planck Institute for Chemical Ecology in Jena, Germany, found that certain strains of the fungus beauveria bassiana Are capable of infecting and killing insects.
“Herbivorous insects have long been known to accumulate plant defense metabolites from their diets as protection against their enemies,” they said in a study recently published in PNAS. “However, as shown here B. bassianaFungal pathogens are capable of inhibiting the toxicity of these dietary defenses and causing disease.
first line of defense
Climate change has recently caused an explosion in bark beetle populations in temperate forests. One species they feed on is Norway spruce. (Pica abies), Which forms organic phenolic compounds known as stilbenes and flavonoids. Stilbenes are hydrocarbons that act as secondary metabolites for plants, and flavonoids, which are polyphenols, are also secondary plant metabolites that are often antioxidants. Spruce combines both classes of compounds with sugars and relies on their antibacterial and antifungal activity.
When metabolized by beetles, spruce sugars are removed through hydrolysis, converting them into aglycones that are even more toxic to micro-invaders. Despite this, some fungi appear to be able to inactivate these compounds. Fungal insect pathogen strains B. bassiana Killing of some of these beetles has been documented in the wild.
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