Sustainable practices for the management of the invasive brown marmorated stink bug, Halyomorpha halys (Stal), on vegetables

Sustainable practices for the management of the invasive brown marmorated stink bug, Halyomorpha halys (Stal), on vegetables

Summary

Field experiments were conducted on two Virginia farms in 2012 and 2013 to determine if brown marmorated stink bug (BMSB) populations could be maintained below economically-damaging levels in bell peppers through implementation of a trap crop. In 2012, there were no differences in BMSB densities on peppers bordered by a row of trap plants of either sunflower or corn compared to control peppers. In 2013, higher numbers of BMSB were observed on control peppers compared to either of the trap crop treatments. There was no effect of trap crop treatment on stink bug damage to pepper fruit in either year. Stink bug damage averaged 30-40% and 20-25% in 2012 and 2013, respectively, regardless of treatment. Also in both years, BMSB parasitism levels from native stink bug egg parasitoids were assessed in southwest Virginia to determine the potential biological control impact on this invasive pest. Egg parasitism levels averaged from 6 to 17% across three years of sampling BMSB eggs in trees and on agricultural crops. In addition, a pyrethroid-incorporated polyethylene mosquito netting was explored as a control tool for protecting vegetables against BMSB. Fresh netting as well as netting that had aged in the field for one year were toxic to BMSB, killing nymphs and adults after constant exposure to the screen for 2 hrs.

• BMSB on sunflower
• BMSB feeding injury on bell pepper
• Bell peppers completely destroyed by BMSB feeding damage
• BMSB on ear of corn

Objectives/Performance Targets

Objective 1: Evaluate the potential of a trap crop of sweet corn and sunflower trap crops to reduce the numbers of BMSB in the primary crop, bell peppers.

In 2013, our goal was to conduct the trap crop experiment again in order to add an additional year of data. 
Pepper plots will be planted in early June on at Kentalnd Farm, near Blacksburg, VA.  Stink bugs will be sampled weekly by conducting timed visual counts on plots.

Objective 2.  To assess natural egg parasitism levels of BMSB in Virginia. 
In 2013, we added a third year to a survey of natural egg parasitism levels of BMSB in western Virginia. 
Over 1,000 eggs will be collected and assessed.
 
Objective 3. Evaluating the potential of new technology to reduce stink bug damage on high value vegetables.
PermaNet 2.0 (Vestergaard –Frandsen) is a polyethylene bed net that has deltamethrin infused into the plastic, which enables it to be slowly released providing long-lasting (up to five years) control of mosquitoes in order to prevent malaria in developing countries. It may be feasible for these nets to be used during the hot, dry season for alternative ways to help control insect pests in crops. This project was designed to evaluate the efficacy of PermaNet 2.0 at controlling brown marmorated stink bug and other agricultural pests.
In 2013, a bioassay will be performed to assess the longevity (or residual efficacy) of Long-lasting insecticidal mosquito screening obtained from Vestergaard-Frandsen Inc. (Sweden) to control BMSB.

Accomplishments/Milestones

Trap cropping

In 2012 and 2013, experimental plots were planted on two farms in southwest Virginia to determine if BMSB populations could be maintained below economically-damaging levels in bell peppers through implementation of a trap crop. The plots were 50 ft by 4 rows. Three replicates were used in 2012 and four replicates in 2013. The control treatment was planted as 4 rows of bell peppers each 20 ft long. Treatments two and three implemented a potential trap crop strategy: one with sunflowers and one with sweet corn. For these treatments, the middle 2 rows of each block consisted of bell peppers while the outer one row on each side was comprised of the trap crop.

Twenty-five peppers per row per plot (50 total) were harvested and assessed for stink bug damage several times during the season. Also, stink bug densities were sampled weekly by counting total stink bugs on 10 plants per row (20 plants/plot).

No statistical difference was discerned in either cumulative numbers of stink bug nymphs and adults over the season (Fig 1), or stink bug-damaged peppers at harvest (Fig 2).

Virginia Tech: BMSB Egg Parasitism Data from Vegetables and Wild trees in southwest Virginia

Thomas Kuhar and Katherine Kamminga (Virginia Tech)

Three-minute visual surveys were conducted weekly from May through September on wild hosts (mostly trees bordering farms) as well as agricultural commodities in western Virginia during the 2011, 2012, and 2013 growing seasons. All stink bug species and life stages were counted and recorded.

Only data from naturally-occurring BMSB eggs were collected. During the survey, all egg masses were collected and number of eggs as well as hatched, unhatched, or parasitized were recorded. Unhatched eggs were brought back to the laboratory and maintained in a growth chamber at 60-80% RH, 27 ± 2°C, and a photoperiod of 16:8 h (L:D) until hatch. Any emerged parasitoids were collected and stored in 70% alcohol. Species identification of parasitoids was confirmed by Christine Diekhoff – USDA-ARS Beneficial Insect Laboratory in Newark, DE.

Egg parasitism numbers were recorded for all egg masses (hatched and unhatched eggs) for 2011, 2012, and 2013. In 2011, a total of 2675 BMSB eggs were found with 203 (7.6%) parasitized and successful emergence of 131 parasitoids. In 2012, 3172 eggs were found with 204 (6.4%) eggs parasitized and successful emergence of 38 parasitoids. In 2013, 1210 eggs were found with 203 (16.8%) parasitized. Based on the emergence and identification of 272 parasitoids, the primary species attacking BMSB in Virginia were Anastatus reduvii and several species of Trissolcus including T. euschisti, T. thyanta, T. edessae, T. brochymenae and Telenomus podisi.

Efficacy of deltamethrin-incorporated mosquito netting for control of BMSB and other agricultural pests

 Lab Study

In the fall of 2011, baseline efficacy studies were conducted using Permanet 2.0 against brown marmorated stink bug (BMSB) adults and striped cucumber beetle. A 50 ft x 6 ft roll of black and white netting was supplied by Vestergaard-Frandsen. The net was cut into 9 cm discs and placed into Petri dishes along with five adult BMSB per dish. This study had four treatments. They were an untreated control, a black treated screen, a white treated screen and an untreated screen. Each treatment was replicated five times. The first test was conducted on 13 September.

From that date, each screen was placed outside in Blacksburg, VA where it was exposed to ambient conditions. Additional experiments were conducted on BMSB adults at 14, 18, 25 and 32 days after exposure (DAE) to the ambient weather. The efficacy of screening after exposure to the natural elements for one year was assessed in 2013. 

Field Studies

In 2012, we conducted a series of field experiments to evaluate efficacy Permanet used as a row cover. Each experiment had three treatments including: 1) Permanet screens, 2) untreated screens, and 3) no screens as a control. Each treatment was replicated five times. Portable row cover frames were built using PVC pipe and were 1.5m long and 0.6m wide. Row covers were randomly placed in an asparagus patch at Kentland Farm, Blacksburg, VA, on 24 April 2012 to evaluate efficacy for controlling asparagus beetles. However, I quickly discovered that using screen to control insect pests in asparagus was not feasible because of the speed of growth and rapid harvest time of the spears.

Eggplant was planted on raised beds with 0.3 m spacing on 4 June. Permanet row covers were placed over five plants per plot on 24 June and the numbers of live flea beetles per plot was recorded on 25 and 28 Jun. These data are summarized in Figure 1.

Muskmelons planted on 4 June were evaluated with the screens being moved from the eggplant and placed over 4 melon plants on 28 June in a completely randomized design. Thirty minutes after the screens were placed; the first evaluation was conducted by counting the number of live and dead cucumber beetles.   The counts were conducted again on 29 June in the same way. On 30 June, an unprecedented storm known as a “Derecho” moved through Kentland Farm and destroyed the row cover frames and the screens. They were rebuilt on 8 July and placed back on the melons and counts were conducted on 9 July.   At this point, the melon plants had become too large to continue to use this set up. These data are shown in Figure 2.

The experiment was also set up in Glenvar, VA to evaluate efficacy against brown marmorated stink bug in peppers. This location had a known infestation of BMSB in 2011; however, we were unable to locate any BMSB on any of the treatments in the tomatoes on any evaluation date. 

• Fig. 2. Stink bug damage to pepper fruit with various trap crop strategies employed.
• Fig. 1. BMSB densities on peppers with two potential trap crop strategies.

Impacts and Contributions/Outcomes

Our attempts to manipulate the behavior of BMSB in a trap crop approach using two preferred host plants, sunflower and corn, were not successful in reducing damage to the cash crop pepper.  A different trap crop design employing a potential push-pull strategy where bugs are lured to the trap crop and repelled from the cash crop may have potential for future studies.  Use of newly synthesized aggregation pheromones of BMSB might also enhance this pest management strategy in the future. 

Baseline assessments of BMSB egg parasitism levels in Virginia will be useful to analyze potential changes in parasitism over time. 

The use of long-lasting insecticidal screening as a crop cover could be a potential strategy, where growers do not want to spray insecticides on crop plants, and have devastating pest pressure from insects.  In our studies, insecticidal screening provided much better insect control than untreated polyethylene row covers.

Outputs: 

Publications and presentations:

Kuhar, T. 2012. Peer-reviewed Webcast. “Pest Threat of the Invasive Brown Marmorated Stink Bug to Tomatoes in the U.S.”. Focus on Tomatoes Webcast, Plant Management Network, International, June 2012. http://www.plantmanagementnetwork.org/edcenter/seminars/Tomato/bmsb/

International IPM Symposium – Memphis, TN, March 2012. Pest threat of the invasive brown marmorated stink bug to vegetable crops in the U.S; T.   Kuhar, Galen P. Dively, Joanne Whalen, George C. Hamilton, Gerald Brust, and Katherine L. Kamminga

Kamminga, K., and T. Kuhar. 2012. Understanding the seasonality of the brown marmorated stink bug in Virginia. Annual Meeting of the Entomological Society of America, Nov 11-14, Knoxville, TN.

Kuhar, T.P, J.D. Aigner, and C.R. Philips. 2013. Management of brown marmorated stink bug in vegetable crops. Oral presentation: Georgia Entomological Society Annual Meeting, April 10-12; Dawsonville, GA.

Kuhar, T. P. and T. Leskey. Brown marmorated stink bug radio interview with Tom Graham Senior Producer, Virginia Insight. WMRA – NPR Affiliate in northernVirginia, May 1, 2013 – Previous broadcasts posted at http://www.wmra.org/programs/virginia-insight

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