By Peter Jentsch
The brown marmorated stink bug [BMSB, Halyomorpha halys (Stål)], has been slow to establish along the Niagara Escarpment, Lake Erie, Finger Lakes and Long Island grape growing regions. However, it has become a permanent resident in the agricultural borders of New York's Hudson Valley. So too, as an urban pest, it has become an unwelcome invader into homes this fall, as many homeowners can attest.
"This past summer was the worst for stinkbugs--hanging out on my townhouse and getting inside the house," said a Poughkeepsie member of the 'BMSB Citizen Science Project.' "Last year was mild with only 25 or so, but I probably captured 150 stink bugs this year."
This project has helped track the spread of the BMSB across the state and has documented a population explosion in the lower to mid-Hudson Valley region in 2012.
The expanding presence of the insect across the state and the increasing number of this species in the urban environment is one measure of the brown marmorated stink bug's success as an invasive pest. The increasing presence of BMSB in orchards and vineyards, reproducing and feeding on fruit, is a definitive sign that the insect is becoming a threat to agriculture in the region. We have crossed an ecological threshold this season with the insect's status having grown from that of an incidental homeowner nuisance to an economically damaging agricultural pest.
Specifically, a number of apple and vegetable growers experienced their first real economic losses from BMSB this season. In Ulster and Orange counties, losses exceeding 21% injury from stink bug feeding was recorded in late season apple varieties and fall harvested organic peppers.
Although BMSB do congregate in homes and structures in high numbers during the winter, they are primarily forest dwellers known to feed on over 133 plant species. The thousands of woodland acres sweeping along the Appalachian, Catskill and Adirondack Mountain ranges through the mid-Atlantic and New England states are hospitable overwintering sites for these insects. Population increases and subsequent damage to fruit are a function of the type and density of food resources provided by native and invasive deciduous trees.
The majority of Hudson Valley vineyards are bordered, at least in part, by deciduous trees comprised of indigenous sugar maple and American ash as well as introduced species including 'Tree of Heaven', Ailanthus altissima, Paulownia and Catalpa. These species can support very high populations of the insect on seed pods that provide both food and shelter. Both the brown marmorated and the native green stink bug, Chinavia halaris (Say), live in these woodlands and begin their movement into vineyard along the wooded edge.
The agricultural-woodland edge is where our attention must then be focused to manage the stink bug complex. Trapping along the vineyard will give you information on the insect presence, however, we have observed over the past three years that insect captures in traps along this edge do not correlate to insect feeding on fruit. They tend to be quite elusive, and much of their feeding activity occurs in the evening. Once insects are found in the traps, diligent scouting of fruit should begin along the vineyard edge.
Management should begin at the onset of migration of BMSB into the vineyard. Applications of insecticides can then be focused along rows of vines closest to woods during earliest periods of migration, with weekly scouting of berries to determine management needs. As there are no established economic thresholds for this insect, low BMSB numbers in agricultural commodities have equated to high damage levels and should be treated with a conservative threshold in mind.
As very few insecticides are effective against the BMSB, it is critical that materials be selected from data available from bioassay studies and field efficacy trials made against the insect. Work done by USDA-ARS in West Virginia, Penn State and Virginia Tech have demonstrated strong efficacy using the pyrethroids bifenthrin (Brigade), fenpropathrin (Danitol); the chloronicotinyl group of insecticides including dinotefuran (Venom), clothianidin (Belay), and to a lesser degree thiamethoxam (Actara). The combination of these two groups provide additional or synergistic efficacy that include pyrethroid combinations of bifenthrin + acetamiprid (Assail), pre-mix formulations of thiamethoxam and λ-cyhalothrin (Endigo ZC), thiamethoxam and chlorantraniliprole (Voliam Flexi), imidacloprid and β-cyfluthrin (Leverage 360), while methomyl (Lannate) and endosulfan (Thionex) are very effective against the BMSB when used alone. It should be noted that many of these materials are rate dependent and should be used at higher labeled rates. Presentations made on BMSB topics since 2011, including efficacy studies, are available on the IPM web site.
Fortunately for viticulturists, grape is not a preferred host for BMSB reproduction, however, the significance of the damage they may cause should not be underestimated. For instance, in the mid-Atlantic grape growing regions of Virginia and Maryland, nymph and adult feeding on berries has been observed and implicated in injury that gives access to rot pathogens such as Botrytis. Often the BMSB feeding will open an initial wound that is further fed upon by secondary insect pests such as multicolored Asian lady beetle, Japanese and June beetles, wasps and bees. Their presence during harvest has also caused delays in sorting, and insects in harvested lugs can lead to contamination of the juice during crush, tainting juice with distasteful aromatic aldehydes from which their name is derived. As they move into the tasting room in the fall they are something of a nuisance, crawling about on tables and walls, unpredictably flying into lights – very uncultured behavior, indeed.
To conclude, the insect is likely to be the greatest threat where vineyards border a woodland as is typical in the Hudson Valley, and to a lesser extent, the Finger Lakes regions. Pheromone lures set along the vineyard perimeter will alert you to the arrival of BMSB, while border scouting of fruit and vines will provide early detection of feeding injury. Employing a conservative threshold of BMSB on the vine will optimize management to reduce the potential for late season injury from berry wounds and increased rot. It is possible that Hudson Valley grape growers will see the BMSB quite early in the 2013 growing season now that it has developed agriculturally damaging population levels. For vineyards in northern, central and western New York, it's unlikely that BMSB will be a pest of concern next season.
For More Information: Stop BSMB: Biology, ecology, and management of brown marmorated stink bug in specialty crops. Website of the USDA Specialty Crops Research Initiative Project on BSMB.
Peter Jentsch is senior extension associate with the department of entomology, based at the Cornell Hudson Valley Laboratory in Highland, NY.