An insect pest native to Asia that suddenly appeared this past summer in Pennsylvania has caught the attention of California entomologists.
They are warning of a possible new threat to the state’s grape growers, tree fruit producers and other farmers.
The brown marmorated stink bug (BMSB) was first sighted in North America in 1996 in tree fruit orchards in northeastern Pennsylvania, says Larry Hull, a Pennsylvania State University entomologist at the Fruit Research and Extension Center at Biglerville.
Although it has since been found in parts of New Jersey, Maryland, Virginia, and West Virginia, the insect had not caused any significant damage to tree fruit crops until this past season.
“Some growers in Maryland and northern Virginia had complained about damage from the insect in 2009,” Hull says. “But, 2010 was the first year when things really got out of hand.”
Some Pennsylvania peach growers lost as much as 50 percent to 60 percent of their crop to the insect, which feeds directly on the fruit. Damage to fruit may include water-soaked lesions and/or cat-facing, ranging from mild to severe.
Conditions in Pennsylvania this past season — an unusually early bloom and very dry, very warm weather — may have spawned a perfect storm, Hull says.
“All the forces came together to create very high BMSB populations, which caught everyone off guard. Whether or not that happens next year, we don’t know, but we’ll certainly be looking for the insect much earlier.”
In the meantime, scientists have launched a major research effort to determine the best ways to control the pest, including appropriate types of insecticides and timing of applications. Pyrethroids, for example, will kill BMSB on contact, but this group of chemicals also kills beneficial insects.
“Using pyrethroids to control BMSB would ruin everything we’ve worked for in terms of Integrated Pest Management over the past 40 years,” Hull says.
In addition to insecticide studies, the researchers are also trying to develop a pheromone specific to BMSB for use in trapping the insects to track populations. Monitoring movement of the insect is complicated by its very broad range of hosts.
It feeds on at least 250 different species of plants; in addition to grapes and tree fruits such as apples, cherries and pears, other hosts include corn, legumes, vegetable crops and landscape ornamentals.
In western states, BMSB has been found in tree fruit orchards in Oregon and, two years ago, in a cargo shipment at an airport in Southern California, says entomologist Walt Bentley, University of California Cooperative Extension IPM specialist.
He advises growers to take finds of unknown species of stinkbugs seriously and to quickly report them to county agriculture commissioners.
The concern about the possibility of BMSB spreading to California and the threat it poses to many of the state’s crops comes on the heels of ongoing efforts by grape growers to turn back the recent invasion of the European Grape Vine Mouth (EGVM).
To prevent a repeat of the problems that pest has caused, he’s calling on grape growers to be vigilant for any signs of BMSB.
“We missedEGVM for a few years and then it became established,” Bentley says. “BMSB has the potential to feed on grapes and, more significantly, to impart an off-flavor to wine if it falls into picking bins. We need to be aware of it before it gets here.”
The insect looks very similar to a number of stinkbugs found in California — including Brochymena. That’s why it’s important to know the identifying characteristics of BMSB, he says. Photos and more information about the insect is available on the UC IPM website:
Because BMSB moves among so many different hosts, migrating throughout the season, there can be considerable overlapping of generations.
“This makes control more difficult, especially if you’re not aware of the insect’s presence,” Bentley says. “You could control for one generation only to have a new group of BMSB move in a few weeks later.”