We love a solid biological control, don’t we? Something natural taking care of something natural, no chemicals needed. A team of researchers from several Midwestern universities is delving into biocontrols to handle Japanese beetles – and reporting some success.

More specifically, Emily Lavely (Michigan State Extension); Erica Hotchkiss, Yoshiko Nomura, Reilly Ford, Julianna Wilson, Rufus Isaacs and David Smitley (Michigan State University); Cary Rivard (Kansas State University); Suzanne Slack (Iowa State University); Robert Wright (University of Nebraska); and Patrick Byers (University of Missouri Extension) are cooperating to consider the biological control of Japanese beetle in the North Central region with the host-specific pathogen Ovavesicula popilliae.

The invasive Japanese beetles can cause significant damage to the leaves and fruit of fruit crops such as apples, cherries, blueberries, grapes and raspberries. Right now, insecticide applications are often needed to protect these crops and harvestable fruit from adult beetle damage.

The research team’s goal is to reduce crop injury due to Japanese beetle damage and minimize pesticide applications using O. popilliae, a fungal pathogen that infects both Japanese beetle larvae and adults. There’s promise here, as Japanese beetle populations declined by 75% over a 20-year period after the introduction of O. popilliae at some southern Michigan golf courses. Both beetle damage and insecticide use declined after the microsporidian was introduced in these areas.

In their 2023 project, Japanese beetles were collected to determine where O. popilliae is present in the North Central region and to identify sites where infected adult beetles could be collected for introduction to sites with high beetle damage.

The spread of O. popilliae has been slow and deliberate where Japanese beetle pressure is high.

Beetles were collected in western and northern Michigan and at sites in Kansas, Iowa, Nebraska and Missouri. In Michigan, Japanese beetles were collected at 48 sites. In Kansas, Iowa, Nebraska and Missouri, beetles were collected at six to 10 different sites. A total of 50 adult beetles were collected at each site. Researchers then identified either the presence or absence of O. popilliae in the beetles from each site.

This project had fruitful results. Collection sites for future introductions of O. popilliae-infected beetles were identified in Michigan (along much of its western border), in Iowa (statewide), in Kansas (the eastern half) and in Nebraska (in the northeast). (More good news: O. popilliae was already established at all the collection sites in southern Missouri.)

The introduction of O. popilliae was recommended by the research team for areas where it is not currently being detected in Michigan, Nebraska, Iowa and Kansas, as a proactive measure.

Want to see if this biocontrol can help you? You can request support for the introduction of O. popilliae-infected Japanese beetles on your operation by contacting Emily Lavely, MSU Extension tree fruit educator, at lavelyem@msu.edu.

This information was courtesy of a poster presentation at the most recent Great Lakes Expo.

by Courtney Llewellyn