BYLINE: Russ Nelson
Japanese beetles cause approximately $450 million in damages every year to private lawns and golf courses alone. Now a UAH researcher at The University of Alabama in Huntsville (UAH), a part of The University of Alabama System, has won a $94,986 United States Department of Agriculture (USDA) grant to help combat this invasive pest. Dr. Carrie Deans is an integrative biologist in the Department of Science at UAH who aims to meet this challenge by investigating the effectiveness of potential biocontrol agents, such as microsporidian parasites. The study is slated to run through June 2026.
A microsporidian pathogen is a fungal parasite that is studied across multiple biological levels, from its highly reduced genome and cellular structure, to its interactions with hosts and the role they play within ecosystems. The project will document the distribution of Ovavesicula popilliae, a microsporidian pathogen that infects grubs and can reduce grub survival and adult fecundity by 50%, as well as the Winsome fly, Istocheta aldrichi, which parasitizes adult Japanese beetles.
“I worked on a similar project as a postdoc at the University of Minnesota, where we surveyed for the same pathogen,” Deans says. “Its distribution isn’t well known outside of Michigan and the northeast. So, when I started as an assistant professor here, I wanted to carry out a similar survey in Alabama.”
That survey is already underway to measure the infection rate of O. popilliae and the parasitism rate of I. aldrichi in adult Japanese beetle populations across different land-use sites throughout Northern Alabama. In addition, the effort calls for forming a stakeholder network and advisory board comprised of representatives from city park boards, golf course superintendents and commodity groups to assist with establishing sampling sites, soliciting feedback, disseminating findings and promoting a Winsome Fly Citizen Science Project to further track I. aldrichi parasitism throughout the state.
The Japanese beetle is well-established throughout most of the eastern and central United States and has also spread to certain areas and portions of states west of the Mississippi River, including Arkansas, Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, Oklahoma and South Dakota.
There is little to no data on these biocontrol agents in Alabama, and their development is essential to providing affordable, targeted, long-term control. The mode of action for how pathogens work to combat these pests, however, is not well understood.
“Neither the Japanese beetle nor O. popilliae are culturable in the lab, so it is difficult to run controlled experiments,” the researcher notes. “However, given that the O. poplilia colonizes and reproduces in the hindgut of the insect, its effects are most likely caused by limiting nutrient reabsorption or disrupting osmoregulation (water and electrolyte balance).”
Japanese beetle adults are highly mobile and can feed on over 300 different plant hosts, including agricultural crops, ornamentals and fruits. The damage caused includes “skeletonized” leaves, leaving a lace-like pattern on the affected plant, as well as harming flowers and fruits. The larvae (grubs) primarily feed on the roots of grasses, causing significant damage to lawns, pastures and golf courses.
“There is federal quarantine to prevent its expansion westward,” Deans explains. “It is quite a common pest of ornamentals, like roses, and some specialty crops, including grape, raspberry, blueberry, apple and soybeans. It isn’t particularly problematic in Alabama versus other states, but developing biocontrol for this pest is important, because it shares habitat with other pollinator species, such as bees.”
This means that using insecticides on Japanese beetles, especially in urban areas, can negatively affect pollinators and other beneficial insects, Deans reports. “Biocontrol agents, on the other hand, are very targeted and reduce the likelihood of these non-target effects.”
As for the future of her research, Deans says, “I have submitted a grant to do another year of surveying, both at sites we surveyed this year and additional sites throughout Central Alabama. There may be some opportunities to set up field trials for this pathogen, but first, we need to figure out if it is already present here. We would also like to measure gene expression in infected grubs/adults to try and better understand the mode of action for the pathogen.”
AloJapan.com