Stink bugs are insects known for their shield-shaped bodies and foul odor when disturbed. While many native stink bug species exist, public concern regarding their environmental impact often centers on invasive species, particularly the brown marmorated stink bug (BMSB). This particular species has garnered significant attention due to its widespread presence and the harm it inflicts on various ecosystems.
Damage to Agriculture
Invasive stink bugs, notably the brown marmorated stink bug, harm agricultural crops. Both adult and immature stages of these insects possess piercing-sucking mouthparts, which they use to penetrate plant tissues and extract plant fluids. This feeding activity leads to visible damage symptoms on fruits, vegetables, and field crops.
On fruits like apples, peaches, and pears, feeding can result in dimpling, discoloration, pitting, and scarring on the surface. In peaches, this damage can lead to a distortion known as “catfacing.” This physical damage makes the produce unmarketable.
In field crops such as corn and soybeans, the damage might not be immediately apparent. In corn, stink bugs feed through the husk, causing kernels to shrivel. For soybeans, they pierce the pods and suck juices from the seeds, leading to flattened pods and a visual symptom called the “stay green” effect, where injured plants remain green longer than healthy ones. This feeding also opens entry points for diseases.
Crop loss and reduced quality result in significant financial burdens for farmers. In some regions, like the mid-Atlantic United States, the brown marmorated stink bug has caused millions of dollars in losses to fruit producers. Their feeding often exhibits an “edge effect,” with higher populations and damage concentrated along field margins.
Impact on Native Ecosystems
Beyond commercial agriculture, invasive stink bugs also affect broader native ecosystems. They feed on a wide variety of non-cultivated plants and trees, with the brown marmorated stink bug alone documented to feed on over 170 host species in North America. This extensive host range includes ornamental plants, shade trees, and wild plants.
The presence of these generalist herbivores can lead to competition with native insects for plant resources. While direct evidence of widespread displacement of native insect populations is still being studied, the sheer numbers and broad diet of invasive stink bugs can strain resource availability within a local ecosystem. This competition could indirectly affect the balance of existing insect communities.
A significant ecological concern is the disruption of local food webs. In their introduced environments, invasive stink bugs often lack the natural predators or parasites that control their populations in their native ranges. This absence allows their numbers to proliferate unchecked, potentially impacting predator-prey dynamics and the overall biodiversity of the ecosystem. Native predators may also find these insects unpalatable due to the defensive compounds they release.
Traits of an Invasive Species
Certain characteristics contribute to why specific stink bugs become environmentally harmful, like the brown marmorated stink bug (BMSB). This insect is native to East Asia, including countries like China, Japan, and Korea. Its introduction to new regions, such as the United States in the mid-1990s, is largely attributed to accidental “hitchhiking” on international cargo, including shipping containers, vehicles, and other goods.
Once introduced, the BMSB’s biological traits enable its rapid establishment and widespread dispersion. It exhibits a high reproductive rate, with females capable of laying up to 400 eggs over several weeks, and in some regions, multiple generations can occur within a single year. This prolific breeding quickly escalates population numbers.
Another contributing factor is its remarkably broad host range, allowing it to feed on over 100 to 170 different plant species, encompassing a wide array of fruits, vegetables, and ornamental plants. This adaptability means the BMSB can thrive in diverse environments, from agricultural fields to suburban gardens and wild areas. The absence of natural predators and parasites that typically regulate its populations in its native habitat further accelerates its spread and impact in invaded regions.
Adult BMSB also seek shelter indoors during colder months, which, while a nuisance to homeowners, inadvertently facilitates their spread to new geographic areas as they are transported with human belongings. These combined traits allow the brown marmorated stink bug to rapidly establish, disperse widely, and exert significant environmental pressure through their feeding habits and unchecked population growth.