MSU Extension Invasive Species

We have learned a lot about BMSB since it was first detected in Pennsylvania in 1998. We know, for instance, that it first becomes a nuisance pest in homes when it seeks shelter in the fall for overwintering. We know that it has a long list of plants on which it will feed, including a number of ornamental plants that are commonly found in Michigan landscapes. We know that it eventually became a serious economic pest in mid-Atlantic orchards, disrupting the current set of pest management practices known as IPM, and that it has become the most important pest close to harvest in apple, pear, peach and nectarine orchards in that region. We have been waiting on pins and needles for it to arrive and wreak havoc in Michigan, but we also have been doing our best to prepare for its arrival.

In mid-late 2018, populations of brown marmorated stink bug (BMSB) increased to a level at which they can now be considered both a nuisance pest in homes throughout the state (see map) and a crop pest of concern in southern Michigan orchards. This article contains a brief summary of some of the activities that Michigan State University researchers and Extension personnel have been undertaking to try to get ahead of this invasive stink bug.

Monitoring population expansion and growth in Michigan orchards

For the last five seasons, my lab has been responsible for coordinating efforts to track BMSB in fruit production areas in Michigan. We have been using traps baited with a combo lure meant to induce BMSB to aggregate and then be captured. With this data have been able to look at trends in population growth and expansion, and at the local level, providing grower cooperators data for their orchard block that could be used to trigger control measures.

What these efforts have shown is that every year the number of BMSB caught in traps continues to grow – particularly in southern Michigan. Through our efforts, there is much more awareness among tree fruit growers about this pest, more scouting is being done on farms, and more control measures are being implemented where BMSB are detected. It is too early to say how bad the damage will be this season, but already we have seen and heard of damage from this pest in orchards where BMSB numbers have been high and expect to see more in apples come out of controlled atmosphere (CA) storage.

Developing attract and kill strategies 

The problem with this pest is that both nymphs and adults feed on the fruiting structures of a wide variety of plants, especially woody plants, and their coloration allows them to be camouflaged against tree bark, making them hard to detect when scouting. John Pote, a post-doc in Dr. Larry Gut’s lab, working in conjunction with a national team effort to develop IPM strategies for this pest through a USDA NIFA funded grant, has been working on possible attract and kill methods for managing the pest in orchards. One of those methods is the so-called “ghost trap” – insecticide-treated netting draped over a post and baited with the combo lure. He will be reporting on these results during one of the apple sessions at the upcoming Great Lakes EXPO in December. 

Screening for parasitoids and other natural enemies

Over the 2017-18 winter, we learned that a very tiny parasitoid wasp called the Samurai Wasp, Trissolcus japonicus, that attacks and kills BMSB eggs and is native to the same part of the world as BMSB, was detected in nearby Ohio. So, as part of the BMSB monitoring network in southern Michigan, we added yellow sticky cards to try to detect them here. At the time of this writing we still have a number of cards to examine under the microscope, searching for possible suspects that are only 2 millimeters long. If we can confirm it is already here in Michigan, that will allow work to begin for actively rearing this wasp to try to increase biocontrol.

In the meantime, Dr. Marianna Szucs is working on screening for native parasitoids that may attack BMSB. She has been setting out BMSB egg masses in areas of high BMSB abundance to attract parasitism and then rearing out whatever has attacked the eggs, back in the lab. Her goal is to identify some of the main native parasitoids that have the potential to contribute to BSMB population suppression and to determine whether their efficiency for finding and killing BMSB eggs might be improved through selection in the lab.

For more information on managing BMSB in Michigan orchards, you can download this free PDF: https://www.canr.msu.edu/ipm/uploads/files/bmsb/MichiganBMSBMngtGuideTreeFruitJuly2018.pdf

Juliana Wilson is a tree fruit integrator with MSU’s Department of Entomology. She can be reached at jkwilson@msu.edu.

Originally ran in Michigan Farmer Magazine.