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THE ASIAN LONG-HORNED beetle, Asian gypsy moth, Sirex noctilio wood wasp and emerald ash borer may possess names that sound like bad-guy characters in the next X-Men cinematic installment, but these real-world villains have caused billions of dollars of crop and tree damage over the course of the past decade — not to mention the overall negative environmental impact posed by insects invading Michigan from other states and countries.
Add to this list of insect evildoers the Brown Marmorated stink bug. The name “stink bug” may make readers laugh at first, but there’s more at stake in Michigan than an insect with a funny name that emits foul odors when you squash it.
During the winter months, the bug seeks to escape the cold by taking up residence in households, but when the weather turns warm and fields, orchards, nurseries and gardens once again become productive, they turn into destructive eating machines. The Michigan Department of Agriculture says stink bugs relish fruit trees, ornamental plants and field crops the same way a certain cartoon cat craves lasagna.
Adult stink bugs grow to an average of 17 millimeters long. The stinkers are shield-shaped and feature shades of brown coloring on their top and bottom. “They are the typical ‘shield’ shape of other stink bugs, almost as wide as they are long,” said Jennifer Holton, public information officer for the Michigan Department of Agriculture and Rural Development.
“(They) superficially resemble several common species of stink bug native to Michigan,” Holton added. “Some of these native species are plant-feeding agricultural pests, while others are considered beneficial because they prey on other insects,” she said.
“To distinguish them from other stink bugs, look for lighter bands on the antennae and darker bands on the membranous, overlapping part at the rear of the front pair of wings,” Holton said. “They have patches of coppery or bluish-metallic colored punctures — small rounded depressions — on the head and pronotum[1]. The name ‘stink bug’ refers to the scent glands located on the dorsal surface of the abdomen and the underside of the thorax.”
Native to East Asian countries, the first stink bugs were detected in the United States about 10 years ago, said Holton. She says stink bug specimens were initially identified in Pennsylvania. They have since spread to “most states on the East Coast” and Michigan, and their presence also has been discovered in California and Oregon.
Females lay eggs throughout their adult lives. The female lays approximately 28 eggs, totalling around 240 eggs in her lifetime.
According to Dr. Anne Nielsen, research associate in organic pest management at Michigan State University, stink bugs more than likely bummed rides on freight ships from American coastal ports, and made their way to current locations by stowing away on trucks and cars. “We believe stink bugs came from Asia through such international shipping ports as Port Elizabeth in New Jersey,” Nielsen said. “From there, they traveled in shipping containers to Allentown, Pa. They’re exceptionally good hitchhikers.”
Nielsen says although specimens have only been spotted in the state since the beginning of this year, “We’ve seen damage that indicates it’s been in Michigan for a while.”
The first actual Michigan sightings of this nasty critter occurred in Eaton and Berrien counties in the southwest portion of the state in January 2011. In March, additional stink bugs were found in Ingham and Genesee counties. Michigan State University entomologists, however, predict the stink bug population will spread widely throughout the Great Lakes region over the next few years.
In her study, “Invasive Forest Pests: Trend and Impacts,” Dr. Deborah G. McCullough of MSU’s departments of entomology and forestry, wrote: “More than 450 non-native insect species that feed on forest trees are established in the United States, and the accumulation rate was relatively steady between 1860 and 2006. Slightly less than 15 percent of the insect species … have caused reportable damage. Sap feeding insects such as scales, aphids, and adelgids dominated the complete list of non-native insects, while foliage feeders were most abundant in the list of damaging pests.”
Nielsen says the BMSB is native to semi-tropical climates, but adds the bugs’ “over-winter survivalist behavior allows them to survive in Michigan.”
The BMSB rides out the winter by hunkering down in houses, where it presents no health or property damage issues. “The best method for controlling BMSB indoors is by sealing entry points like cracks around window and door trim, exhaust vents, air conditioners, ceiling fixtures,” said Holton. “Once they’ve gained entry, vacuuming live and dead bugs is the best option. Pesticide treatments are not recommended because they will not prevent additional invasions,” she said.
While acknowledging the presence of bugs in a person’s home might be annoying, Dr. Chris DiFonzo, a field crops entomologist at MSU, and Nielsen agree the real threat stink bugs pose is the damage they can do to Michigan agriculture.
Holton emphasizes that BMSB is unlike the emerald ash borer and Dutch elm disease, which decimated millions of Michigan trees. The ash borer insect and elm disease attacked and killed trees, she notes, but BMSB “attacks the fruit of the plant or tree and not the tree itself.” “However, it will be a very serious pest for producers of agricultural crops and nurseries.”
BMSBs feed on fruit fluids by puncturing the plants’ tissues with their stylet — the needle-sharp extension the bug uses to break through the fruit’s surface. This puncturing and sucking process produces dimples, deformities or scars, known as “cat-facing,” on the fruit’s skin and can make the product unmarketable.
Nielsen places stink bug damage to tree fruit in the Mid-Atlantic States in the $37 million range, but emphasizes that the greater diversity of crops in Michigan poses a much greater risk.
“BMSB has a very wide host range unlike many pests which only feed on specific plant material,” said Holton. “Because of its wide host range and the damage resulting from its feeding, BMSB has the potential to have a great impact on agricultural crops, particularly those that are not normally treated for insect pests during the growing season.”
Holton says the BMSB could be “devastating for a variety of fruits, vegetables, field crops and ornamental plants. Potentially impacted crops in Michigan include apples, peaches, corn, cherries and others,” she said. “It has also been reported on many ornamental plants, weeds, soybeans and beans for human consumption.”
Ken Nye, Michigan Farm Bureau spokesman, says his organization has been taking an active role with MSU researchers and the Michigan Department of Agriculture and Rural Development, as well as with the U.S. Department of Agriculture.
“We’ve been working with MSU’s farm extension program to disseminate information to growers,” Nye said. “The perception is that a large number of farm commodities are threatened by damage by the stink bug.”
Nye added: “We are letting growers know what control methods are going to work, and the many different resources we’re bringing to bear — from biological controls growers can utilize to monitoring weather patterns that might help us determine a scientifically timed process based on the bug’s growth cycle and at what point the bug can be dealt with most effectively.”
Holton says early detection and rapid response programs are “crucial for dealing successfully with exotic pests which threaten the state’s agricultural interests and impact our natural resources and environment.”
She adds that while detection of BMSB is not good news, “the fact that it’s been detected early provides us the opportunity for outreach to the affected communities and to dial-up control strategy recommendations — including applying for emergency use pesticide registrations, if necessary.”
Holton also said the department will be working in concert with MSU to “identify possible controls for both agricultural and home use,” she said. “For ag-based use, other states such as Maryland and Pennsylvania have had some success with pyrethrum-based compounds.”
Nielsen said the best defense against the BMSB is to slow it from spreading. “We’re working out a rapid response protocol that will use USDA-approved insecticides as well as control and monitoring techniques.”
The good news, according to Nielsen, is that agricultural pesticides already in use have proven effective in trials conducted by MSU, and controlling or eradicating the pest won’t require entirely new chemical compounds.
DiFonzo also says the BMSB population can be managed using what she calls “off-the-shelf” agricultural chemicals.
If that’s the case, perhaps Michigan can remove the stink bug threat and enjoy the sweet smell of success.
Michigan Department of Agriculture and Rural Development: https://www.michigan.gov/mda/0,1607,7-125-1572_28248-250475--,00.html
“Qualitative Analysis of the Pest Risk Potential of the Brown Marmorated Stink Bug (BMSB), Halyomorpha halys (Stål), in the United States,” United States Department of Agriculture Animal and Plant Health Inspection Service, Plant Protection and Quarantine, October 2010: https://www.michigan.gov/documents/mda /BMSB_Pest_Risk_Potential_-_USDA_APHIS_Nov_2011_344862_7.pdf
[1] The pronotum is one of three portions of the stink bug’s thorax, which bears the first set of legs. The pronotum’s exoskeleton is what gives the bug its shield-like shape.
