Ambrosia beetles are being studied in two different countries, in two different contexts and by two different teams of Michigan State University researchers. 

In the tropical forests of the Philippines, Dr. Anthony Cognato and a team of MSU entomologists investigate the variety of bark and ambrosia beetles. In Michigan, the MSU Tree Fruit Entomology Lab’s conducts research about the invasive ambrosia beetles species in Michigan apple orchards.

The combined efforts help the lab identify stressed trees by monitoring beetle habits, said Heather Leach, a research technician at the tree fruit entomology lab.

Cognato, who has researched this beetle subfamily for 30 years, strives to document the biodiversity of arthropods around the world. 

There are around 4000 species of these beetles and two thirds live in tropical areas like the forests of the Philippines, Cognato said, and ambrosia and bark beetles have little to no information recorded. 

Cognato first takes beetle DNA samples to create a family tree to help build a foundation for future applied research. His work also aims to understand the role ambrosia and bark beetles play outside of their natural habitat. 

“Some of them are important economic pests," Cognato said.

In the Midwest, ambrosia beetles have a tendency to burrow into apple trees, but they do not harm them — although they do leave a physical mark much to farmers’ dismay. At least 30 ambrosia beetle species have been introduced into United States in the past 50 years.

“They bore into wood and create fungal galleries, so they themselves don't eat the wood, but they deposit a fungus that basically grows onto the wood and then they eat that fungus," Leach said. "So they sort of farm whatever tree is their host."

The insects burrow into the apple trees when the tree shows signs of stress, such as being flooded, dehydrated, overheated or facing other adverse situations. While the holes from the burrows aren’t aesthetically pleasing, they do show when an orchard isn't thriving.