Bark beetles use the smell of fungus to pick the best trees to infest

Fungus-infected trees give off a foul odor, which attracts bark beetles.Bark beetles can burrow through bark and devastate entire forests

To spider wetzel

Bark beetles may use receptors on their antennae to detect and feast on fungus-infected trees.

Eurasian spruce bark beetle (the printer itself) – found in Europe, Asia and parts of Africa – burrows into the bark of Norway spruce (red spruce) where they feed and reproduce. By doing so, thousands of pine-nut-sized insects can kill vast swaths of forest.

Researchers already knew that bark beetles prefer to attack trees weakened by certain fungi. This is because fungi offer benefits that protect insects from nasty microbes and parasites, and may supplement a beetle’s diet. “They bring down giant trees en masse,” says Jonathan Gerschenson of the Max Planck Institute for Chemical Ecology in Germany.

However, it was not known how the beetles sensed infected hosts. Gershenzon and his Dineshkumar Kandasamy at Lund University in Sweden explored this by identifying compounds released from infected spruce trees. Grosmania penicillataThey found that fungi produce two major compounds, camphor and thujanol.

The researchers then examined the beetle’s anatomy and found odor-detecting neurons in its antennae that could detect camphor and thujanol.When they gave insects a choice between being healthy or not G. penicillataWhen spruce bark was infected in the laboratory, all beetles were attracted to the infested wood. The presence of compounds produced by the fungi not only attracted the beetles, but also drove them to tunnel into the bark.

Insects were not attracted to wood if the bark of the tree was infected with a type of fungus that produced a variety of compounds that were not beneficial to the beetles. …and avoid or ignore what is not good for them,” says Kandasamy.

Jiri Hulcr of the University of Florida says a more thorough investigation of which fungi produce chemicals that are attractive to beetles could have strengthened this research. “I can’t say that… G. penicillata is particularly special. It may be a natural function of members of the microbial soup growing in dead wood. “

Researchers are optimistic that identifying compounds that attract bark beetles could lead to more effective feeding efforts. Researchers are now using a cocktail of enticing pheromones to lure beetles en masse into traps, but this method “has not been very successful in developmental cycles that began in the last decade,” says Gershenzon. say. He hopes that adding these fungus-related compounds to the trap will increase its effectiveness.

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