IPM for the Brown Marmorated Stink Bug: Part 1
Original article appeared in the IPM Practitioner (vol. 34, no. 3). This online version was produced in partnership between the Bio-Integral Resource Center and the Northeastern IPM Center.
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| The black pyramid trap, shown here, can be used to monitor brown marmorated stink bug populations. Bugs are attracted by aggregation pheromones at the top of the pyramid. (Courtesy B. Butler) |
By William Quarles
The brown marmorated stink bug (BMSB), Halyomorpha halys, is an invasive species native to China, Japan, and Korea. It was first noticed in Pennsylvania in the late 1990s and was established in Pennsylvania by 2001. Genetic analysis shows the initial U.S. introduction likely came from Beijing, China, possibly from shipping containers. Populations are growing exponentially, and it spreads by hitchhiking on shipping containers and vehicles. Adults can fly, which aids local dispersal (Hoebeke and Carter 2003; Nielsen et al. 2013; Lee et al. 2013; Xu et al. 2014).
From the original introduction, the pest has now spread in 13 years to 41 states and Canada (Lee et al. 2013; StopBMSB.org 2014). It appeared in Oregon in 2004, and has been in California since 2005. Large breeding populations have established near Los Angeles and Sacramento (Hoddle 2013; StopBMSB.org 2014; Ingels and Varela 2014).
H. halys will eat almost anything. It attacks more than 170 different plant species, and prefers to eat many of the same foods as humans, especially beans, garden vegetables, and tree fruit. It is a threat to commercial agriculture, landscape ornamentals, and backyard gardens. It is also a structural pest, as large populations invade houses, trying to overwinter (StopBMSB.org 2014; Lee et al. 2013; Inkley 2012).
More than $37 million damage was done to apples in the mid-Atlantic states in 2010. Growers reacted by a four fold increase in pesticide applications. Pesticides disrupted IPM programs and led to secondary outbreaks of mites, aphids, and scales in orchards (Leskey et al. 2012a).
Most pyrethroids had limited effectiveness, as about one-third of the bugs recovered after knockdown. As a result, growers turned to endosulfan, methomyl, and neonicotinoids. Though more effective, these pesticides have environmental problems, including toxicity to bees (Leskey et al. 2012b; Funayama 2012; Quarles 2014a).
This article outlines an IPM program that will help control the brown marmorated stink bug (BMSB), while sparing beneficial insects and bees.
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| Adult, H. halys |
Why More Successful than Native Stink Bugs
We have many species of native stink bugs in the U.S. These have always been rather low level pests. The invasive H. halys is more successful due to lack of specific natural enemies, reproduction in large numbers, wide host range, resistance to cold weather, effective overwintering strategies, and increased survival due to global warming (Lee et al. 2013). At crop sites throughout the mid-Atlantic states, H. halys is now the predominant stink bug pest (Nielsen and Hamilton 2009ab).
Though there is some predation, our native parasitoids have not yet adapted to the pest. Reproduction is prolific, as one female can lay an average of 240 eggs per generation. H. halys overwinters as adults, emerging in spring to start feeding when temperatures exceed 17 °C (63 °F). Long daylight hours, warm temperatures, and food lead to sexual maturation within about two weeks. In the Northeast there is one breeding generation a year, but two generations have been seen in West Virginia, and five generations a year are possible in tropical climates (Leskey et al. 2012a; Lee et al. 2013).
Survive Cold Weather
H. halys is more cold resistant than most stink bug species now living in the U.S. For example, mean winter temperatures of 4 °C (39.2 °F) will kill 81% of the southern green stink bug, Nezara viridula, but only 31% of H. halys (Kiritani 2006). U.S. spring populations of H. halys in 2014 were not reduced by the unusually cold winter of 2013 (StopBMSB.org 2014).
H. halys has effective overwintering strategies. Most U.S. stink bugs overwinter in weeds and crop debris. So crop sanitation and weed removal can discourage overwintering populations. But H. halys overwinters with a forest theme. It chooses leaf litter, crawls underneath tree bark, and can hide in wooded areas that make it more difficult to intercept. And hordes of H. halys invade structures to spend the winter in comfort (Lee et al. 2013).
Increased Survival from Global Warming
Global warming is contributing to the increase and spread of many pests. Pest ranges are spreading, and early springs increase the number of generations a year (Quarles 2007; IPCC 2013). Global warming may have contributed to increase and spread of H. halys. Temperatures in Japan and the U.S. have increased by nearly 1 °C (1.8 °F) over the last 100 years. When mean winter temperatures are averaging about 4 °C (39.2 °F), every 1 °C (1.8 °F) increase can increase winter survival rates of H. halys by about 16.5% (Kiritani 2006; 2007).
Stink Bug Damage
Adult bugs are about the size of a dime (see Box A), but they are way more than ten cents worth of trouble. H. halys sucks plant juices through a feeding stylet. Injection of saliva can cause enzymatic damage, brown spots, surface depression, and mealy consistency in apples. Individual kernels of sweet corn are destroyed. Bean pods are scarred and deformed. Grape berries are destroyed, and wine may be tainted. Though most damage is to fruit trees, greater than 20% damage has been seen in pepper, tomato, eggplant and okra (Leskey et al. 2012a). Damage to soybean includes deformed seeds, delayed maturity and reduced yields (Nielsen et al. 2011). H. halys can also vector diseases such as Paulownia witches’ broom (Lee et al. 2013).
In the Northeast, adults of H. halys feed on apples both early and late in the season. Eggs are laid on apple, nymphs hatch, then walk away from apples to another host. After nymphs develop into winter adults in July and August, they fly back to feed on apples. Damage to apples at harvest can exceed 25% in New Jersey and more than 70% in Pennsylvania. Pears and peaches are also damaged (Nielsen and Hamilton 2009b; Leskey et al. 2012b).
In the Northeast, adults are first found in late April on ornamentals such as princess tree, Paulownia tomentosa, and crop hosts such as apple and pear. Egg laying starts at the end of May, and this coincides with the first appearance of adults in blacklight traps (see Monitoring below). Egg masses are seen by mid-June. Preferred hosts in July are viburnum and ash. Peak appearance in blacklight traps is in August, showing late season movement of fall adults to feeding sources (Nielsen and Hamilton 2009a). Pheromone traps also show peak populations in August (Weber et al. 2014).
H. halys feeds through bark on trees and ornamentals, leaving weeping holes of exudates. Martinson et al. (2013) found two-thirds of trees surveyed in Maryland had H. halys present, and about 15% of trees had exudates from feeding injuries. Native hymenoptera such as paper wasps, yellowjackets and ants feed on the injuries. This feeding can be viewed as good for native species, or if there are a lot of problems with yellowjackets, ants, and wasps as structural pests, a bad thing.
What Makes a Stink Bug Stink?
H. halys invades structures, and one of the problems is the odor produced. Stink bugs produce odorous secretions, probably to deter predators (Aldrich 1988; Millar 2005). The defensive secretions vary with each species, but often contain unsaturated aldehydes (Borges and Aldrich 1992; Noge et al. 2012). The major stink chemical of H. halys is (E)-2-decenal. It can be detected in concentrations of 0.3 micrograms per liter (Baldwin et al. 2014).
Stink bug defensive secretions can actually attract enemies such as spiders and parasitoids (Aldrich and Barros 1995; Mattiacci et al. 1993). As well as defensive secretions, stink bugs produce aggregation pheromones, and these may or may not have a noticeable odor (Weber et al. 2014). Aggregation pheromones are commercially available (see Resources), and are especially useful for monitoring and for attract and kill formulations (see Box B).
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