The brown marmorated stink bug (Halyomorpha halys) is an insect in the family Pentatomidae, native to China, Japan, Korea, and other Asian regions. In September 1998, it was collected in Allentown, Pennsylvania, where it is believed to have been accidentally introduced. The nymphs and adults of the brown marmorated stink bug feed on over 100 species of plants, including many agricultural crops, and by 2010–11 had become a season-long pest in orchards in the Eastern United States. In 2010, in the Mid-Atlantic United States, $37 million in apple crops were lost, and some stone fruit growers lost more than 90% of their crops. Since the 2010s, the bug has spread to countries such as Georgia and Turkey and caused extensive damage to hazelnut production. It is now established in many parts of North America and has recently become established in Europe and South America.
Description Adult brown marmorated stink bugs are approximately long and about as wide, forming the shield shape characteristic of bugs in the superfamily Pentatomoidea. They are generally dark brown when viewed from above, with a creamy white-brown underside. Individual coloration may vary, with some bugs being various shades of red, grey, light brown, copper, or black. The term "marmorated" means variegated or veined, like marble, which refers to the markings of this species, including alternating light-colored bands on the antennae and alternating dark bands on the thin outer edge of the abdomen. The legs are brown with faint white mottling or banding.
The nymph stages are black or very dark brown, with red integument between the sclerites. First instar nymphs have no white markings, but second through fifth instar nymphs have black antennae with a single white band. The legs of nymphs are black with varying amounts of white banding. Freshly molted individuals of all stages are pale white with red markings. Eggs are normally laid on the underside of leaves in masses of 28 eggs, and are light green when laid, gradually turning white.
As in all stink bugs, the glands that produce the defensive chemicals (the smell) are located on the underside of the thorax, between the first and second pair of legs.
Behavior
The stink bug can emit an odor through holes in its thorax as a defense mechanism against being eaten by predators. However, simply handling the bug, injuring it, or attempting to move it can trigger it to release the odor. The odor is due to trans-2-decenal and trans-2-octenal. The smell has been characterized as a "pungent odor that smells like cilantro".
Reports on human cases are rare; the stink bug's body fluids are toxic and irritating to human skin and eyes. One case of keratitis has been reported in Taiwan.
Mating During courtship, the male emits pheromones and vibrational signals to communicate with a female, who replies with her own vibrational signals, as in all stink bugs. The insects use the signals to recognize and locate each other. Vibrational signals of this species are noted for their low frequency, and one male signal type is much longer than any other previously described signals in stink bugs, although the significance of this is not yet clear.
Diet The brown marmorated stink bug is a sap-sucking insect (like all Hemiptera or "true bugs") that uses its proboscis to pierce the host plant to feed. This feeding results, in part, in the formation of dimpled or necrotic areas on the outer surface of fruits, leaf stippling, seed loss, and possible transmission of plant pathogens. It is an agricultural pest that can cause widespread damage to fruit and vegetable crops. In Japan, it is a pest to soybean and fruit crops. In the U.S., the brown marmorated stink bug feeds, beginning in late May or early June, on a wide range of fruits, vegetables, and other host plants, including peaches, apples, green beans, soybeans, cherries, raspberries, and pears.
In North America
The brown marmorated stink bug was accidentally introduced into the United States from China or Japan. It is believed to have hitched a ride as a stowaway in packing crates or on various types of machinery. The first documented specimen was collected in Allentown, Pennsylvania, in September 1998. Several Muhlenberg College students were reported to have seen these bugs as early as August of that same year. Between 2001 and 2010, 54 sightings were reported of these bugs at shipping ports in the United States. However, stink bugs are not listed as reportable, and no action is required to remove the insect. This allowed the insect to enter the United States relatively easily, as it can survive long periods in hot or cold conditions.
Other reports have the brown marmorated stink bug documented as early as 2000 in New Jersey from a blacklight trap run by the Rutgers Cooperative Extension Vegetable Integrated Pest Management program in Milford, New Jersey.
In 2002, in New Jersey, it was found on plant material in Stewartsville and was collected from blacklight traps in Phillipsburg and Little York. It was quickly documented and established in many counties in Pennsylvania, New Jersey, Delaware, Connecticut, and New York on the eastern coast of the United States.
By 2009, this agricultural pest had reached Maryland, West Virginia, Virginia, Tennessee, North Carolina, Kentucky, Ohio, Illinois, and Oregon. In 2010 it was found in Indiana, Michigan, Minnesota, and other states.
As of November 2011, it had spread to 34 U.S. states and by 2012 to 40, and showed an increase of 60% in total numbers over 2011.
Their populations have also spread to southern Ontario and Quebec, Canada. They have recently been found in southern British Columbia and southern Alberta.
Population increase
As of 2010, 17 states had been categorized as having established populations, and several other states along the eastern half of the United States were reported as having more than normal numbers of stink bugs. Stink bug populations rise because the climate in the United States is ideal for their reproduction. In optimal conditions, an adult stink bug can develop within 35 to 45 days after hatching.ARS. 2010b. Brown Marmorated Stink Bug: Research Updates. USDA-ARS, Kearneysville, WV. 6 pp. Female stink bugs can lay 400 eggs in their lifetimes. The bug can also produce at least one successful generation per year in all areas of the United States, no matter the climate. In warmer climates, multiple generations can occur annually, which can range from two generations in states such as Virginia to six generations in California, Arizona, Florida, Louisiana, Georgia, and Texas.
The addition of two more generations allowed the population to explode, leading to the establishment of several other populations in neighboring states. Currently, no environmental limiting factors are apparently slowing their distribution across North America. They are also extremely mobile insects, capable of moving from host to host without causing disruption in their reproductive processes. Currently, populations are estimated to continue to grow and spread to other states and provinces, especially during unusual periods of warm weather.
Agricultural effects
The brown marmorated stink bug is a serious agricultural pest that has been readily causing damage to crops across the Eastern United States. They feed on an array of plants, including apples, apricots, Asian pears, cherries, corn, grapes, lima beans, peaches, peppers, tomatoes, and soybeans. This makes them extremely versatile, as they do not require a specific plant on which to feed. To obtain their food, stink bugs use their stylets to pierce the plant tissue to extract the plant fluids.McPherson, J. E., and R. M. McPherson. 2000. Stink Bugs of Economic Importance in America North of Mexico, Boca Raton, FL. 253 pp. In doing so, the plant loses necessary fluids, which can lead to deformation of seeds, destruction of seeds, destruction of fruiting structures, delayed plant maturation, and increased vulnerability to harmful pathogens. While harvesting the plant's juices, the stink bug injects saliva into the plant, creating a dimpling of the fruit's surface and rotting of the material underneath.
The most common signs of stink bug damage are pitting and scarring of the fruit, leaf destruction, and a mealy texture to the harvested fruits and vegetables. Most times, the signs of stink bug damage make the plant unsuitable for sale in the market, as the insides are usually rotten. In field crops such as corn and soybeans, the damage may not be as evident as the damage seen in fruit plants. When stink bugs feed on corn, they go through the husk before eating the kernels, hiding the damage until the husks are removed during harvesting. The same damage is seen in soybeans, as the stink bug goes through the seed pods to acquire the juices of the seeds. One visual cue of stink bug damage to soybean crops is the "stay green" effect, where damaged soybean plants stay green late into the season, while other plants in the field die off normally. One can usually tell that a field of crops is infected because stink bugs are known for the "edge effect", in which they tend to infest crops from the edges of the field first, typically 30-40 ft.
Control Control of stink bugs is a priority of the United States Department of Agriculture, which has developed an artificial pheromone that can bait traps. Because the bugs insert their probosces below the surface of fruit and then feed, some insecticides are ineffective; in addition, the bugs are mobile, and a new population may fly in after the resident population has been killed, making permanent removal nearly impossible. With soybean infestations, spraying only the perimeter of a field may be the most effective method of preventing stink bugs from damaging the crops. However, even this method is limited, as new populations move back into the area, or the existing population simply moves to unaffected areas. Evidence also shows that stink bugs are developing resistance to pyrethroid insecticides, a common chemical used to combat infestations. Other insecticides currently in field trials that are showing promising results are oxamyl (96% mortality rate) and moribund (67% mortality rate). Many other commonly used insecticides are merely used to keep these insects out of fields, rather than actually killing them. The most successful method of protecting apples found thus far is the use of kaolin clay. , native predators such as wasps and birds were showing increased signs of feeding on the bugs as they adapted to the new food source. Managing this pest species is challenging because few effective pesticides are labeled for use against them.
Similarity in appearance to native species Easily confused with Brochymena and Euschistus, the best identification for adults is the white band on the antennae. It is similar in appearance to other native species of shield bug, including Acrosternum, Euschistus, and Podisus, except that several of the abdominal segments protrude from beneath the wings and are alternatively banded with black and white (visible along the edge of the bug even when wings are folded) and a white stripe or band on the next to last (fourth) antennal segment. The adult rice stink bug (Oebalus pugnax) is distinguishable from the brown marmorated stink bug by noting the straw color, the smaller size, and the elongated shape of the rice stink bug.
In Europe