Halyomorpha halys, also known as the brown marmorated stink bug (BMSB), is an insect in the family Pentatomidae that is native to China, Japan, the Koreas, and Taiwan. It was accidentally introduced into the United States, with the first specimen being collected in September 1998. The brown marmorated stink bug is an agricultural pest and by 2010-11 had become a season-long pest in U.S. orchards. It has recently established itself also in Europe and South America.
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Description
The adults are approximately 1.7 centimetres (0.67 in) long and about as wide, forming the shield shape characteristic of other stink bugs. They are various shades of brown on both the top and undersides, with gray, off-white, black, copper, and bluish markings. The term marmorated means variegated or veined like marble. Markings unique to this species include alternating light 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 stink glands are located on the underside of the thorax, between the first and second pair of legs, and on the dorsal surface of the abdomen.
Behavior
The brown marmorated stink bug is a sucking insect (like all Hemiptera or "true bugs") that uses its proboscis to pierce the host plant in order 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.
The brown marmorated stink bug is more likely to invade homes in the fall than others in the family. The bug survives the winter as an adult by entering houses and structures when autumn evenings become colder, often in the thousands. In one home more than 26,000 stinkbugs were found overwintering. Adults can live from several months to a year. They will enter under siding, into soffits, around window and door frames, chimneys, or any space which has openings big enough to fit through. Once inside the house, they will go into a state of hibernation. They wait for winter to pass, but often the warmth inside the house causes them to become active, and they may fly clumsily around light fixtures. Two important vectors of this pest are the landscape ornamentals Tree of Heaven and Princess Tree.
The odor from the stink bug is due to trans-2-decenal and trans-2-Octenal. The smell has been characterized as a "pungent odor that smells like coriander." The stink bug's ability to emit an odor through holes in its abdomen is a defense mechanism meant to prevent it from being eaten by birds and lizards. However, simply handling the bug, injuring it, or attempting to move it can trigger it to release the odor.
During courtship, the male emits pheromones and vibrational signals to communicate with a female, which 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.
In the United States
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 there were fifty-four reported sightings of BMSB at shipping ports in the United States. However, stink bugs are listed as non-reportable, meaning that they do not need to be reported and there is no action required to remove the insect. This allowed the insect to enter the United States relatively easily as they are able to survive long periods of time in hot or cold conditions.
Other reports have the brown marmorated stink bug recovered as early as 2000 in New Jersey from a black light trap run by the Rutgers Cooperative Extension (RCE) Vegetable Integrated Pest Management program in Milford, New Jersey. In 2002, it was again collected in New Jersey from black light traps located in Phillipsburg and Little York and was found on plant material in Stewartsville. 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 this pest was found in additional states including 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.
Population increase
As of 2010, seventeen states had been categorized as having established BMSB 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 will develop within 35 to 45 days after hatching. Female stink bugs are capable of laying four hundred eggs in their lifetime. BMSB is also capable of producing 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 states such as California, Arizona, Florida, Louisiana, 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 there does not appear to be any environmental limiting factors that are slowing their distribution across the United States. They also are extremely mobile insects capable of moving from host to host without causing disruption in their reproductive processes. Currently it is estimated that BMSB populations will continue to grow and spread to other states, 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 a wide 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 to feed on. To obtain their food, stink bugs use their stylets to pierce the plant tissue to extract the plant fluids. 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. In most cases the signs of stink bug damage makes the plant unsuitable for sale in the market as the insides are usually rotten. In field crops such as corn and soy beans 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 soy beans, 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 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 thirty to forty feet from the edge of the field. Farmers or individuals who suspect having stink bugs in their crops should contact their respective State Department of Agriculture for information on how to manage the infestation and possible ways to prevent future incidences.
Control
Control of stink bugs is a priority of the Department of Agriculture which has developed an artificial pheromone which can be used to bait traps. Because the bugs insert their proboscis 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. In the case of soybean infestations research shows that spraying only the perimeter of a field may be the most effective method of preventing stinkbugs 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. There is also evidence that stink bugs are developing a 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 the 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. As of 2012, native predators such as wasps and birds were showing increased signs of feeding on the bugs as they adapt to the new food source. Managing this pest species is challenging because there are currently few effective pesticides that are labeled for use against them. Researchers are looking into ways to effectively control this species but many more experiments are needed to develop a consistent pesticide.
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 (4th) 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.
Predators
In China, Trissolcus japonicus, a parasitoid wasp species in the family Scelionidae, is a primary predator. This species is not currently present in the U.S., but is undergoing study for possible introduction. The major problem with this idea is the possibility that japonicus will also become an invasive species with no native predators. Before introducing the Chinese wasp, scientists are trying to find natural predators of the stink bug already present in the United States. To do so they have studied other species of parasitoid wasps native to the United States. They found that several other species of the parasitoid wasps attacked stink bug eggs in Virginia soybean fields. Researchers have also experimented with different spider species as well as the Wheel bug. Several spider species attacked both the eggs as well as live stink bugs. Pill bugs eat stinkbug eggs. The Wheel bug, however, was the most voracious predator and attacked the eggs as well as stink bugs more consistently. Scientists are hoping that other animals such as birds will eventually begin preying on stink bugs as populations continue to rise.
Life cycle
Source of the article : Wikipedia
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