Brown marmorated stink bugs (BMSB) are invasive insects considered an agricultural pest and structural nuisance. The goal of this research was to evaluate the effectiveness of physical exclusion in preventing indoor populations of BMSB. Over a 15-month period, a total of only eight overwintering pests were intercepted. Low trap counts, combined with results from resident surveys, suggest that basic observational research is needed to better understand BMSB behavior around structures and to enhance overwintering pest management.
Background and justification
The brown marmorated stink bug (BMSB) is an invasive insect from Asia that was accidentally introduced to the United States near Allentown, Pennsylvania. Since its discovery in the 1990s, BMSB has expanded its range to 41 U.S. states and Canada. It feeds on over 100 different host plants, causing physical damage and economic losses. For example, in 2010, the apple industry reported losses totaling $37 million from BMSB (Leskey et al. 2012).
For urban pest professionals, BMSB are a problem when adults enter buildings as overwintering pests. The prevailing theory is that BMSB orient toward broad vertical surfaces in the fall when temperatures, daylight or host plant quality decrease. BMSB then seek dark crevices, using their antennae to detect pheromones and locate other stink bugs at close range (Toyama et al. 2006; 2011). Insects remain hidden until warm temperatures cause them to explore outside of their harborage. On warm winter afternoons, bugs indoors may be attracted to the light of windows during the day and artificial lights at night, such as reading lamps and electronics. This brings BMSB into close contact with homeowners and causes distress. In the spring, when temperature and day length increase, overwintered BMSB return outdoors to feed and reproduce.
Management of BMSB, both in agricultural and urban areas, has relied on insecticide applications to kill all life stages, and is particularly effective against nymphs and overwintered adults (Leskey et al. 2013). However, many products currently employed to control BMSB have reduced efficacy as residues against adult insects, while label changes to pyrethroids limit how these products can be applied by urban pest professionals.
Physical exclusion is often promoted as a practice to reduce pest numbers indoors. Sealing cracks and crevices around doors, windows, utility access points, chimneys, siding and fascia have been promoted in extension bulletins and technical guides for BMSB (Day et al. 2011). Despite its purported efficacy, however, to date there have been no scientific evaluations of pest exclusion. Therefore, the goal of this project was to scientifically evaluate the use of physical exclusion to prevent indoor invasion of BMSB.
Materials and methods
This research took place at a condominium complex in Hartsdale, New York where residents identified BMSB populations as problematic in recent years. Within the complex, two to four individual units (condominiums) are joined to form a block, providing an ideal design to test exclusion for a pair of units: one, a treatment that received pest exclusion and the other, a control that did not. Eleven pairs and one triplet of units enrolled in the study for a total of 23 condominiums.
In July 2015, window and doorframes on treatment units were inspected for gaps around flanges (Figure 1). A readily available clear silicone-based sealant was used to seal gaps where exclusion efforts had not been complete or the material had failed. This did not include window weep holes, which allow water drainage (Figure 2). Sealant was examined in July 2016 to verify that gaps remained closed.
SilenTraps and GLOStiks were operated from August-November 2015, March-May 2016 and September-November 2016, which correspond to periods of BMSB activity around buildings. When devices were in operation, they were serviced once per month to replace batteries on GLOStiks, SilenTrap glue boards and GLOStik tubes as needed. In addition, residents were asked to keep track of the number of BMSB they observed during the year.
A preliminary survey was administered to residents in June 2015 for baseline information about BMSB activity within their unit, with a final survey administered in November 2016.