[Invasive Pests] Stink Bugs: A Continuing Threat

The brown marmorated stink bug (BMSB), more commonly known as the stink bug, has quickly emerged as a significant pest throughout the United States and is believed to have been introduced from Asia. The BMSB was introduced into the Lehigh Valley region of Pennsylvania in the mid- to late-1990s, but most likely it existed before this time period, with the concentration of species thriving in the Mid-Atlantic region.

The BMSB belongs to the class Hemiptera, which easily can destroy fruit, plants and vegetable crops. As a member of the class of Hemiptera, this pest ranks among “true bugs,” which are estimated to include up to 80,000 species worldwide. True bugs undergo gradual metamorphosis and have piercing and sucking mouthparts. True bugs typically feed on fluids ranging from large tree plant roots, where they drain fluids, to other Hemiptera, such as bed bugs, which pierce the skin to extract blood from its host.

Infestations in homes and businesses are increasing. Crop damage to more than 300 different kinds of plants are slowly topping previous year-over-year estimates, which have continued to contribute to economic losses for many local, national and international food processors. Environmental factors, such as increased wet winters and soaring spring temperatures, have created naturally conducive conditions that ideally allow stink bugs to reproduce more rapidly year after year.

As the industry continues to seek new and innovative ways to control and eradicate this pest, it is important to remember that total and complete reliance on pesticide applications is insufficient in controlling any pest. We should instead implement an Integrated Pest Management (IPM) approach to address all pests, not just the BMSB. The basis of IPM is the implementation of a complementary and multi-disciplinary approach to solving pest problems. IPM methods include biological controls, cultural controls, physical controls and chemical controls.
 

Multiple approaches.

Many different and exciting approaches continue to be developed to control and eradicate the BMSB.

Biological controls. One major advance that may prove to be an effective biological approach is the importation of parasitic wasps (Trissolcus) from Asia, primarily Japan and China. Parasitic wasps have been used for fly control and recently have been utilized in addressing the BMSB in the United States. The parasitic wasp has been tested to track down BMSB eggs, then implant their smaller eggs within the stink bug eggs and, over time as the larvae develops, it ends up feeding on the stink bug eggs and emerges in their place. This is why in Asia, where the BMSB is prevalent, it has not been as large of a problem. In the United States, where the BMSB has no “true” natural predators, it has been nearly impossible to gain substantial biological control until recently. Other biological controls include the use of Tachnid flies, which are beneficial insects that feed on various insects, including the BMSB and other destructive and nuisance pests.

Cultural controls. Cultural controls have been in existence long before the development of synthetic pesticides, primarily pyrethroids. With the advent of synthetic pesticides, cultural controls became discontinued or discounted as ineffective. Cultural controls seek to prevent rather than to eliminate, but their validity should not be overlooked. One of the best cultural controls for the BMSB is to control weeds on a property through the use of herbicides during peak seasons. Aside from curtailing BMSBs this approach also will prevent the appearance of other invaders, such as rodents and ants.

On farms and other mass-producing facilities, the effective use of annual crop rotation can prove to be an effective method by starving pests out; additionally, crop rotation limits the ability of destructive pests (such as BMSBs) to establish themselves on an ongoing basis. Trap cropping, a method in which crops are planted to steer pests away from more valuable commodity crops, is another approach that can be implemented. Intercropping, as well, has proven to be an effective approach; it mixes various crops and the result is unattractive to BMSBs. From an operational and maintenance standpoint this approach can be difficult and all approaches mentioned can be tailored to the individual account. The most important biological control always is maintaining proper sanitation so that all areas can be inspected and especially so that harborages can be discovered.

Physical controls. Physical controls seek to physically remove the pest from a particular environment, whether that be a home or business. The smaller the scenario encountered when dealing with the BMSB, the more effective the physical control method becomes. On a large-scale, multi-faceted operation, physical controls can be utilized but are more effective for monitoring purposes than for eradication of an active infestation. Various traps have been devised in recent years that attract pests and simply trap them inside the device. The advantage of these traps is the pest’s presence can effectively be confirmed, but the negative aspect when dealing with the BMSB is they simply won’t go into the trap when another preferable harborage source exists. There is one major pitfall that occurs when an applicator or client relies solely on this product and/or overapplies pesticides: more BMSBs are attracted to the area, producing more damage to crops/vegetation.

On a smaller scale, in a residential setting, tactics such as sealing cracks and crevices around windows and doors, the removal of air conditioners and especially sealing around air conditioners, continues to remain an effective means of exclusionary pest control. The USDA has recently conducted a lot of research into the use of aggregate pheromones to aid in trapping for the BMSB. This research is parallel to past research completed on the use of aggregate pheromone devices that are currently in use by PCOs. As this research continues, the outlook for developing an effective aggregate pheromone device in combating the BMSB is promising.

Chemical controls. Chemical control methods can be effective but they do have limitations. Pesticide resistance is one major problem and, as such, the applicator needs to properly rotate products. At present time, pyrethroids and carbamates seem to be the two pesticide classes of choice for BMSBs. Pesticide rotation strategies continue to play a large role in achieving control since this will offset and/or delay resistance to pesticides. Labels and laws are updated regularly; therefore, it is extremely important to be aware of the label for each product that you are applying and also to monitor its efficacy. Elimination of the BMSB species may not be realistic in all instances, but an achievable and measurable degree of control can be accomplished through the implementation of effective rotation strategies combined with non-chemical approaches within the IPM scheme.
 

Increasing Public Awareness.

Increased public awareness of pesticide effects has increased the importance of our industry to continue to embrace non-chemical strategies that, in the long run, can satisfy client concerns while continuing to provide clients with ample control. Strategies such as starting an IPM program at the onset of an infestation will go a long way, as opposed to only using pesticides as a means of control. Education will help pest management professionals who have limited experience with this pest.
 

Outlook.

Continued monitoring and intervention by state and local municipalities in areas that have identified occurrences of BMSBs and have been identified as susceptible to frequent invasions of BMSBs is critical. With globalization and interstate commerce of plants and food products, the likelihood that this pest will begin to ubiquitously appear increases as does its impact. The outlook for this pest appears to be one of recurrence in already infested areas and the spread of BMSBs to new areas. Research on the use of predatory insects to manage this pest shows promise. In areas where control has been difficult, the use of predatory insects in combination with the safe application of pesticides may be the only approach that can achieve sustainable control.

The author is associate entomologist, food safety and service specialist, RK Environmental Services, Westwood, N.J., and can be reached via email at pstieglmayr@giemedia.com.