Managing Brown Marmorated Stink Bug in Michigan Orchards

Managing Brown Marmorated Stink Bug in Michigan Orchards Julianna Wilson 1, Larry Gut 1, Michael Haas 2, Matthew Grieshop 1, Kristin Poley 1, William Shane 3 1. Department of Entomology, 2. Trevor Nichols Research Center, 3. Southwest Michigan Research and Extension Center MICHIGAN STATE UNIVERSITY Last updated December 2016 KEY POINTS: Adult BMSB hibernate in manmade structures, woodlots, and other places outdoors; it is a nuisance pest in many MI homes. First suspected commercial fruit damage in the state by BMSB was in southwest MI beginning in 2014. BMSB produces one generation per season in Michigan. Each BMSB female lays eggs in clusters on leaves of one of many different host plants. Adults and nymphs cause fruit damage when they feed, but the damage only becomes apparent weeks later or after fruit are brought out of storage. Peaches are attractive at any stage when fruit is present; apples become attractive mid-season. Use on-farm monitoring to assess BMSB populations and when to begin management. Fruit can be protected from damage with effective registered insecticides. Target insecticide applications at the tops of trees and orchard edges. DISTRIBUTION, BIOLOGY, KEY CHARACTERISTICS Distribution of BMSB in Michigan Brown marmorated stink bug (BMSB), Halyomorpha halys, is a tree-loving pest native to Asia. It was first detected in the U.S. mainland in Pennsylvania in 1996. By 2006, it was causing major damage to apple and peach crops in the mid- Atlantic region. The first Michigan detection was in Berrien County in 2010, followed several years later by reports of suspected BMSB fruit damage. Nuisance reports from several thousand Michigan residents as of Spring 2016 indicate that BMSB populations are well-established in the southern Lower Peninsula. All together BMSB has been reported in 55 Michigan Counties, including two counties in the Upper Peninsula. Key features for identification Adult BMSB have several key features to help distinguish them from native brown stink bugs (Fig. 1). Adults are ½ inch long by 5/8 inch wide, with a banded pattern along the margin of their abdomen and banding on their antennae and legs; they also have smooth shoulders rather than toothed like some of our native species. Eggs are greenish-white in color and laid in a cluster of up to 28 eggs on a leaf of a preferred host. There are five nymphal stages. The first nymphal stage is black and red. The other four nymphal stages are brown like the adult (Fig. 2). Fig. 1. Key identifying features of brown marmorated stink bug adults include a banded pattern along the abdomen and antennae with smooth, rounded shoulders. Biology and lifecycle BMSB adults emerge from overwintering sites (e.g. woodlots, manmade structures) in response to a day length of 13.5 hours, which is late April in Michigan (Table 1). Egg laying begins after 135 degree days (DD = base 57.2 F) have accumulated, around the end of May. Females lay clusters of up to 28 greenish-white eggs on the undersides of leaves of preferred host plants, and between 10-20 egg clusters in their lifetime. Feeding and development continue through five nymphal stages before molting into the adult stage in late July or early August. High densities of BMSB and the potential for damage become more likely at this time. The summer generation continues to feed before moving to overwintering sites beginning in early September through November. The adult produces an attractant, called an aggregation pheromone, which attracts other adults to the same location. This is why clusters of adults can be found gathering on buildings. One generation is thought to occur in Michigan (Fig. 2).

2 MANAGING BROWN MARMORATED STINK BUG IN MICHIGAN ORCHARDS BMSB Lifecycle as it Relates to Michigan Orchards Peaches are vulnerable to feeding damage as early as June by winter emerging adults and early instar nymphs Overwintered adults break diapause in late April to lay eggs on a variety of wild and crop hosts Later instar nymphs and summer adults move from peaches and other crops to apples beginning in early-august Feeding in apples by nymphs and adults principally occurs in August and September As temperatures drop, summer adults take shelter for winter in woodlots and manmade structures Fig. 2. Life cycle of the brown marmorated stink bug and its overwintering behavior as it relates to orchards. Adults overwinter in manmade structures then emerge in late April to find suitable host plants (green part of lifecycle). Clusters of eggs are laid on suitable wild and crop host plants beginning at the end of May. When population levels are high near preferred crops, nymphs and adults will move into orchards and cause damage when they feed on fruit, but the damage will not be apparent until weeks later. Orange indicates when peaches and nectarines are vulnerable to damage in June and July. Red indicates when apples are vulnerable to damage in August and September. Elements of this illustration courtesy of the Nielsen Fruit Lab, Rutgers University. Table 1. Estimated dates when brown marmorated stink bug (BMSB) life stages are expected to appear during the season. The model is based on using a 13.5-hour day as the biofix for BMSB emerging from overwintering, 135 degree days (DD base 57.2 F) until egg laying begins, and then another 964 DD (base 57.2 F) for those eggs to develop into adults. 1 st overwintered New (summer) generation Event -> Egg laying begins adult expected adults expected Environmental cue -> 13.5 hr day 135 DD* (base 57.2 F) 1103 DD* (base 57.2 F) Benton Harbor 27-Apr 27-May Various nymph stages 28-Jul Romeo 26-Apr 27-May present from end of May 3-Aug Fennville 26-Apr 27-May through mid-august 7-Aug Sparta 25-Apr 27-May 13-Aug Hart 25-Apr 28-May 13-Aug Traverse City 23-Apr 29-May 13-Aug *Degree days were calculated by selecting individual Enviro-weather (https://mawn.geo.msu.edu/) stations and creating custom reports using the Baskerville-Emin method starting with the date when day length reached 13.5 hours in a given area in 2016.

MANAGING BROWN MARMORATED STINK BUG IN MICHIGAN ORCHARDS 3 Host plant preferences The list of plants on which BSMB will feed is long, including many wild, agricultural, and ornamental plants. Preferred hosts are non-native ornamental trees and shrubs that bear seed pods or fruit, but they will also feed on and damage herbaceous fruiting plants. BMSB move in and out of different crops over the course of a season, therefore, it is useful to know whether other high risk crops and ornamentals are near your orchards when considering where to focus monitoring efforts. Table 2 shows how tree fruit and nuts compare with other specialty crops grown in Michigan in terms of relative risk of damage by BMSB. Woodlands are thought to be important overwintering sites and as a non-crop food source. Table 2. Relative risk of damage by brown marmorated stinks bugs to Michigan specialty crops, field crops, and ornamentals. Risk Level Tree Fruit & Nuts Berries & Grapes Vegetables Field crops Ornamentals High apple, hazelnut, nectarine, peach 1, pear (Asian and European) grape 2 beans (green, pole, snap), edamame, eggplant, okra, pepper, sweet corn, Swiss chard, tomato dry beans, field corn, soybeans, sunflowers bee-bee tree, black cherry, catalpa, crab apple, English holly (female), Japanese pagoda tree, multiflora rose 4, Peking lilac tree, redbud, tree of heaven 4, wild raspberry 4 Moderate apricot, cherry 2 Low (sweet and tart), plum, walnut blackberry, blueberry 2,3, raspberry cranberry, strawberry asparagus, broccoli, cauliflower, collard, cucumber, horseradish, lima bean, tomatillo carrot, garlic, kohlrabi, leeks, lettuce, onion, potato, spinach, sweet potato, turnip winter wheat 5 black walnut, flowering dogwood, littleleaf linden, maples, serviceberry blackgum, ginkgo, Japanese maple, kousa dogwood 1 Additional risk potential due to bark feeding. 2 Potential risk of taint/contamination. 3 Considered moderate to high risk. 4 Considered to be a particularly attractive and important host plant. 5 Considered to be a population source more than a crop damaged by BMSB. BMSB in orchards When BMSB are abundant, most tree fruit grown in Michigan should be considered at moderate to high risk from BMSB feeding damage. In the high-risk group are apple, nectarine, peach, and pear. In the moderate risk group are apricot and cherry. As populations continue to increase in Michigan, damage to stone fruit and apples is expected to increase with nymphs appearing in June and mixed populations of nymphs and adults peaking in August and September. BMSB nymphs and adults can both cause damage in fruit and vegetable crops, but the damage will not be detected until weeks or even months later especially in the case of fruit that is stored before being sold. Keep records of where damaged fruit occurred on your farm those will be the orchards to monitor closely. Fruit damage in peaches and nectarines Peaches, nectarines, and apricots are vulnerable to damage soon after fruit set until harvest. In these crops, BMSB monitoring should start after shuck-split. Soon after bloom, damaged fruit are likely to drop. Midseason feeding damage will produce cat-facing injury, weeks after the feeding has occurred, which is typical of plant bugs (Fig. 3, left). Late season damage will look more like water-soaked depressions in the fruit (Fig. 3, right), but again, damage will go unnoticed until weeks after the feeding has occurred. Photo: Utah State University Photo: Doug Pfeiffer, Virginia Cooperative Extension Fig. 3. Mid-season feeding by stink bugs causes cat-facing injury in peaches and nectarines (left); injury from stink bug feeding at a later stage will appear as water-soaked lesions (right).

4 MANAGING BROWN MARMORATED STINK BUG IN MICHIGAN ORCHARDS Fruit damage in apples Photo: Doug Pfeiffer, Virginia Cooperative Extension fruit is likely to abort. Damage occurring later in the season may be confused with bitter pit Photo: Amy Irish-Brown, MSU Extension Fig. 4. Injury to apple may be confused with bitter pit except that it will appear anywhere on the apple vs. on the calyx end where bitter pit typically appears (above left). When fruit is cut, flesh will be corky (upper right); later season injury can go unnoticed until fruit is taken out of storage. Apple and pear fruitlets may be injured as early as late May where populations are very high, but the majority of damage in these crops is expected in August and September, with damage becoming apparent weeks after feeding has occurred. Similar to stone fruit, if damage occurs soon after bloom, damaged Photo: William Shane on the surface, but when the fruit is sliced, the interior will be corky (Fig. 4, left). If damage occurs 1-2 weeks before harvest, apples may show no visible signs of injury (Fig. 4, right), but will develop brown and necrotic areas in the flesh during post-harvest storage. TRAPPING FOR NYMPHS & ADULTS While BMSB are fairly easy to identify and distinguish from native stink bugs, they can be highly cryptic in orchards. They prefer the tops of trees and their coloring exactly matches tree trunks. Traps are easy to deploy and check, but the area of influence for a single baited trap appears to be relatively small, and not terribly efficient. Therefore, it is important to place them near the crop, and if using a Rescue brand trap, make sure that the fins of the trap touch the trunk or post so that nymphs are able to crawl up into it (Fig. 5). It adds to the reliability of the information to combine trapping with other sampling methods such as jarring of upper branches of fruit trees over beating trays in orchard edges close to woodlots. Traps are used in mid-atlantic orchards to provide a threshold for taking management action, but their recommended threshold needs to be tested under Michigan conditions. For now, traps may be useful in determining whether BMSB are in the vicinity. Several different kinds of traps are available commercially (Fig. 5), but all tend to have a pyramid shape with fins that need to either touch the ground or tree trunk so that nymphs can walk up into them. Lures are attractive to both nymphs and adults. Several commercial lures are available, but all of them appear to have a relatively limited range of attraction. In other words, BMSB need to be in the vicinity in order to pick up on the scent. Each lure type should be changed according to the labeling, but generally on a 3-4 week interval. Photo: Julianna Wilson Photo: Michael Haas Fig. 5. Examples of traps used to monitor for BMSB. Both the pyramid trap on the left and the Rescue brand trap on the right need to be baited with a lure that is attractive to nymphs and adults. The fins of the Rescue trap must touch the trunk or trellis post to which it is attached for the nymphs to be able to crawl up into it. Traps are most useful when placed in orchard margins that are adjacent to woodland or river and stream habitats. It is recommended that a line of 3-4 traps be placed along the orchard margin in orchards that are at highest risk of infestation. Traps should be checked, at minimum, once per week.

MANAGING BROWN MARMORATED STINK BUG IN MICHIGAN ORCHARDS 5 BMSB CONTROL As BMSB populations continue to increase in Michigan, growers are strongly encouraged to scout for BMSB. An effective management program entails: 1) Knowing where preferred host plants are located in relation to vulnerable orchards, 2) Scouting and/or trapping for BMSB in orchard margins, 3) Keeping good records of which orchards show signs of damage at harvest or post-harvest, and 4) Using the best application timing and method for insecticides effective against BMSB that are registered for use in your crop. Pesticide registrations and recommendations will change as we learn how to better manage this pest, and growers can remain informed through the MSU BMSB website, local Extension Educators, and the MSU Extension News for Agriculture (www.msue.anr.msu.edu/topic/info/fruit). Chemical control. BMSB management is a new consideration for Michigan s tree fruit producers. The good news is that many of the insecticides currently registered for use against other common tree fruit pests will also provide good protection against BMSB. Commercially available materials from the pyrethroid, neonicitinoid and carbamate chemical classes should be effective against both BMSB nymphs and adults. Tables 3 and 4 list materials registered for use in Michigan peach and apple orchards that would be effective against BMSB. Always follow the specific label restrictions for the target crop, being aware of the pre-harvest interval (PHI), re-entry interval (REI), other pests that may be present, and potential impacts on existing IPM programs (see the Michigan Fruit Management Guide E- 154 for more details). Fig. 6. Good coverage is essential to protecting tree fruit from BMSB feeding damage. Expect to use high spray volumes, full cover applications, and returning with an application of a different effective insecticide after a rainfall event. The target market may also play a role in the decision process for selecting a particular material if the target market s maximum residue limit (MRL) is set lower than the U.S. tolerance. When used according to the label, detectable residues for most of the materials listed in Tables 3 and 4 should not exceed export tolerances for Michigan apple markets. For more information, please consult the Apple MRL charts available online (http://tinyurl.com/applemrlchart) or the free online decision support tool for selecting pesticides close to harvest in cherry and apple (http://mrl.msu.edu/). There is only one OMRI approved product Azadirachtin that shows some activity against BMSB in peach, but is not recommended for use in apple due to the potential for phytotoxicity damage after the pink stage. Aza-Direct has a 0-day PHI in stone fruit and may be used without MRL concerns because it is a biological. Managing BMSB in APPLES. Orchards adjacent to woodlots and next to peach orchards are considered to be at highest risk of invasion. Scout for BMSB in apple using limb-jarring of upper limbs over a beating tray to determine whether BMSB are present in a given orchard. Keep track of where damaged apples were found from the previous season these are the orchards that you will want to pay especially close attention for potential management the following year. Timed to occur with second generation codling moth, orchards that are at risk of BMSB damage should receive a full cover of an insecticide that works on both codling moth and BMSB, making sure that the tops of the trees are well covered. Monitor with pheromone-baited traps to help determine population pressure. This will also help to determine whether followup applications every 7 days with a perimeter spray until harvest are needed. Use traps as described above to monitor areas of concern on your farm and continue a BMSB management program when the threshold has been met, which is 10 BMSB nymphs or adults captured per trap in a single week.

6 MANAGING BROWN MARMORATED STINK BUG IN MICHIGAN ORCHARDS Managing BMSB in PEACHES and NECTARINES. Begin monitoring for BMSB in peaches in mid to late May, especially along wooded edges. In high-risk orchards or where damaging populations are found, weekly border sprays on 5-10 acre plots (crop border plus first full row) have been shown to be an effective strategy in New Jersey. Dispersal to peaches can be initially monitored using baited traps placed at the edges (see details on traps on page 6). Initiating sprays when BMSB are first detected has not been evaluated but might be an appropriate timing. Peaches on the interior should be monitored for injury or bug presence. If BMSB is detected on the interior a full block spray should be done. Potential for biological control of BMSB. Biological control could help suppress BMSB populations in Michigan, but it is not expected to be a stand-alone tactic for controlling BMSB. Common predators found in Michigan orchards that will feed on BMSB eggs include spiders, lady beetle adults and larvae, minute pirate bugs, lacewing larvae, crickets, and grasshoppers. There are also predators that will feed on BMSB nymphs and adults, including spiders, assassin bugs, and predatory wasps. Parasitoids small, non-stinging wasps that lay their eggs inside the eggs of their host have a greater potential to help suppress BMSB populations over the long-term. Although several native parasitoids have been collected in low numbers from BMSB egg clusters in Michigan orchards, it is a parasitoid native to the same part of Asia as BMSB that holds the most promise. This parasitoid has been in quarantine for evaluation before being released in North America, but in the meantime has found its way to North America and is now found in several US states where BMSB is well established. Nearly all natural enemies benefit from access to nectar-producing flowers in orchard margins. Areas maintained as pollinator habitat (Fig. 7) provide food and refuge from in-orchard pest management for natural enemies of brown marmorated stink bugs and other pests as well. Fig. 7. An example of a wildflower planting maintained for pollinators and other beneficial insects.

MANAGING BROWN MARMORATED STINK BUG IN MICHIGAN ORCHARDS 7 Effective insecticides for controlling BMSB in orchards. Table 3. Insecticides that are effective against stink bugs in Michigan PEACHES. Trade Name Active Ingredient Class PHI (days) Relative efficacy against BMSB Max rate per acre Actara thiamethoxam neonicotinoid 14 E 4.5-5.5 oz Admire Pro imidacloprid neonicotinoid 0 G 2.8 oz Assail 30 SG acetamiprid neonicotinoid 7 G 8 oz Aza-Direct* Azadirachtin botanical 0 G 1-2 pints; 3.5 pints under heavy pest pressure Belay 2.13 SC clothianidin neonicotinoid 21 G 6 oz Danitol 2.4 EC fenpropathrin pyrethroid 3 E 21.3 oz Endigo ZC lambda-cyhalothrin & thiamethoxam pyrethroid & neonicotinoid 14 E 5-5.5 fl oz Lannate 90 SP methomyl carbamate 4 E 2 lbs Leverage 360 SE imidacloprid & beta-cyfluthrin neonicotinoid & pyrethroid 7 E 2.8 oz Pounce 25 WG permethrin pyrethroid 14 E 6.4-16 oz Scorpion 35 SL** dinotefuran neonicotinoid 3 E 5.25-7 oz Voliam Xpress 112 SC lambda-cyhalothrin & pyrethroid & diamide 14 G 6-12 oz chlorantraniliprole Warrior II 2CS lambda-cyhalothrin pyrethroid 14 E 1.28-2.56 fl oz Table 4. Insecticides that are effective against stink bugs in Michigan APPLES. Trade Name Active Ingredient Class PHI (days) Relative efficacy against BMSB Rate per acre Actara thiamethoxam neonicotinoid 14 E 4.5-5.5 oz Admire Pro imidacloprid neonicotinoid 7 G 2.8 oz Assail 30 SG acetamiprid neonicotinoid 7 G 2.5 oz Belay 2.13 SC clothianidin neonicotinoid 7 G 6-12 oz Danitol 2.4 EC fenpropathrin pyrethroid 14 E 16-21.3 oz Endigo ZC lambda-cyhalothrin & thiamethoxam pyrethroid & neonicotinoid 35 E 5-6 oz Lannate 90 SP methomyl carbamate 14 E 1 lb Leverage 360 SE imidacloprid & beta-cyfluthrin neonicotinoid & pyrethroid 7 E 2.8 oz Voliam Xpress lambda-cyhalothrin & chlorantraniliprole pyrethroid & diamide 21 G 6-12 fl oz Warrior II 2CS lambda-cyhalothrin pyrethroid 21 E 1.28-2.56 fl oz Notes: Aza-Direct is also labeled for use on apple and pear, but not after the pink stage as it can result in phytotoxicity; tank mixing with oil-based products will also cause plant injury. For more information, please refer to the specimen label for each material (http://www.cdms.net/label-database). See also the 2016 Michigan Fruit Management Guide E-0154. Although products listed in these tables are labeled for use in these crops, not all have BMSB listed on the label. * OMRI registered product. ** There is a supplemental label for use of Scorpion on peach and nectarine.

8 MANAGING BROWN MARMORATED STINK BUG IN MICHIGAN ORCHARDS For more information MSU Integrated Pest Management BMSB Resource page: http://www.ipm.msu.edu/invasive_species/brown_marmorated_stink_bug MSU Extension News for Agriculture Fruit & Nut page: http://msue.anr.msu.edu/topic/info/fruit Michigan Fruit Management Guide: Bulletin E0154 http://shop.msu.edu/product_p/bulletin-e0154.htm Pesticide Label Database: http://www.cdms.net/label-database Michigan Apple & Cherry MRL Tool: http://mrl.msu.edu Complete list of BMSB non-crop host plants: http://www.stopbmsb.org/where-is-bmsb/host-plants Acknowledgements We thank Anne Nielsen for providing graphics for Figure and updated details about BMSB biology. Michigan Apple Committee supports part of Dr. Wilson s position as Tree Fruit Integrator. MSU is an affirmative-action, equal-opportunity employer, committed to achieving excellence through a diverse workforce and inclusive culture that encourages all people to reach their full potential. Michigan State University Extension programs and materials are open to all without regard to race, color, national origin, gender, gender identity, religion, age, height, weight, disability, political beliefs, sexual orientation, marital status, family status or veteran status. Issued in furtherance of MSU Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Ray Hammerschmidt, Interim Director, MSU Extension, East Lansing, MI 48824. This information is for educational purposes only. Reference to commercial products or trade names does not imply endorsement by MSU Extension or bias against those not mentioned.