Progress 10/01/06 to 09/30/11
Outputs
OUTPUTS: Project 1. Brown marmorated stink bug (BMSB) efficacy trials in soybean. Three replicated field experiments were conducted in Orange Co. to determine the efficacy of selected insecticides against BMSB. Treatments were broadcast using a backpack sprayer in August; sweep net samples were used to count adults and nymphs at multiple days after treatment. Plant samples were taken at maturity to determine the extent of BMSB injury to seed. Project 2. Statewide survey and cage studies to evaluate the presence and impact of BMSB in soybean. A statewide survey of soybean fields was conducted to determine the presence and range of BMSB. Scouts sampled fields in 42 counties throughout Virginia from August 2 to October 10, 2011, making 240 field visits. A series of field cages were used to determine impact of BMSB feeding on soybean seed and pods. Different numbers of late instar nymphs and adults (0, 2, 4, or 8 per row ft) were introduced at both the R4 and R6 soybean growth stages. Insects were eliminated from cages after two weeks. Plants were allowed to mature. At harvest, seed number, seed weight and seed quality factors were determined. Project 3. Cage studies to determine the impact of BMSB on cotton. BMSB and green stink bug adults were released in large (6 x 6-ft) cages in August, allowed to feed for 7 days, then were eliminated. Bolls from row 1 were removed on day 8, grouped by size, and were examined for warts and stains. Bolls from row 2 were allowed to mature and were hand-harvested, weighed, ginned, and submitted for lint analysis (AFIS). Two small (20 x 12-cm) cage studies were also performed where stink bugs were confined to individual cotton bolls. One test evaluated adults, the other nymphs. There were three infestation levels (untreated, BMSB adult or nymph, and green stink bug adult or nymph) and three boll diameters (1.8, 2.8, and 3.2 cm) from first or second sympodial positions. A single caged boll was considered an experimental unit; each treatment was repeated 28 times. PARTICIPANTS: Jessica Samler, David Owens, and Amanda Koppel, Virginia Tech, Dept. of Entomology (graduate students); Katherine Kamminga, Virginia Tech, Dept. of Entomology (postdoc); Galen Dively, Univ. of Maryland, Dept. of Entomology; Joanne Whalen, Univ. of Delaware, Dept. of Entomology and Wildlife Ecology, Jack Bacheler, Dept. of Entomology, North Carolina State University TARGET AUDIENCES: Growers, extension agents, independent crop consultants, university specialists and scientists PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Project 1. In trial 1, all rates of Vydate L, Lannate LV, and Cobalt Advanced evaluated were efficacious against BMSB at 1, 6, and 13 days after treatment (DAT). By 22 DAT, very few BMSB remained in the untreated control. Similar results were seen in adjacent trial 2 with Belay (with and without Kaiso 24WG and Baythroid XL), Baythroid XL, Orthene 97, Endigo ZC, Brigade 2EC, and CMT 4586. The initial BMSB population was highest in trial 3, which included the same products as trial 2. At 2 and 7 DAT, all products had significantly lower total BMSB counts than the untreated control, but 3 of 9 treatments had lost effectiveness by 16 DAT. Project 2. BMSB was first found on August 2 at growth stage R3 (beginning pod) soybean in Orange and Fauquier Counties in low numbers (less than 1 per 15 sweeps). It was also found at R2 (full flower) in Fauquier County on August 9. The highest number of BMSB recorded was 15 per 15 sweeps. This was likely a false low based on our observation that this species tends to drop when approached, thereby reducing the potential catch in the sweep net. Project 3. Large cage studies indicated that BMSB adults caused more injury than green stink bug adults to bolls with diameters of 3.8 cm and greater. From the small cage study, we learned that BMSB adults caused significantly more internal warts than green stink bug adults when isolated on 2.8 and 3.2-cm diameter bolls. Green stink bug adults caused more warts and minor stains on 1.8-cm diameter bolls. These findings are important because boll damage thresholds have considered large bolls to be safe from stink bug feeding, but this may not be the case when BMSB are present.
Publications
- Koppel A., D. Herbert, T. Kuhar, S. Malone, G. Arrington. 2011. Efficacy of selected insecticides against eggs of Euschistus servus (Say) and Acrosternum hilare (Say) (Hemiptera: Pentatomidae) and the egg parasitoid, Telenomus podisi Ashmead (Hymenoptera: Scelionidae. J. Econ. Entomol. 104: 137-142.
- Bacheler J., D. Herbert, J. Greene, P. Roberts, M. Toews. 2011. Concept to delivery: a pocket-size scouting decision aid for stink bug scouting ion the southeast. Proc. Beltwide Cotton Confs. P. 1093.
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Progress 10/01/09 to 09/30/10
Outputs
OUTPUTS: Project 1. Stink bug egg chorion studies: Previous efficacy studies found that many insecticides used by growers could be having an adverse effect on egg parasitoids (Telenomus podisi) developing in the eggs of the brown stink bug (Euschistus servus), while unhatched stink bugs experienced lower levels of mortality. One plausible explanation for this was that insecticides might enter parasitized eggs more readily via oviposition wounds. Parasitized E. servus eggs, as well as nonparasitized stink bug (Acrosternum hilare, E. servus, Murgantia histrionica, and Podisus maculiventris) eggs, were examined using electron microscopy. Egg response to perforation by a tungsten probe served as a control. Project 2. New thresholds and decision tools for managing stink bug in cotton: Cotton entomologists in the southeastern states (VA, NC, SC, GA, AL) collaborated to develop new thresholds and scouting systems to improve stink bug management practices in cotton. Replicated field experiments were conducted to determine economic levels of stink bug induced boll damage that change with crop maturation. The relationship of external stink bug feeding symptoms to internal boll damage was also determined. New field scouting procedures were developed and vetted with selected independent crop consultants. New scouting tools were developed. Project 3. Statewide survey and cage studies to evaluate the presence and impact of the brown marmorated stink bug (BMSB) in soybean: A statewide survey of soybean fields was conducted to determine the presence and range of the new invasive pest, the BMSB. Forty soybean fields in 24 counties throughout Virginia were monitored from August 2 to September 23, 2010. A series of field cages was used to determine impact of stink bug feeding on soybean seed and pods. Different numbers of late instar nymphs (0, 1, 2, or 4 per 0.91 row m) were introduced at both the R4 and R6 soybean growth stages. Insects were eliminated from cages after two weeks. Plants were allowed to mature. At harvest, seed number, seed weight and seed quality factors were determined. PARTICIPANTS: Amanda Koppel and David Owens, Virginia Tech, Dept. of Entomology (graduate students), E. W. Westbrook, Virginia State Univ., Jack Bacheler, North Carolina State Univ., Dept. of Entomology, Jeremy Greene, Clemson Univ., Dept. of Entomology, Phillip Roberts, Univ. of Georgia, Dept. of Entomology, Galen Dively, Univ. of Maryland, Dept. of Entomology, Eric Blinka, Monsanto Co. TARGET AUDIENCES: Growers, extension agents, independent crop consultants, university specialists and scientists PROJECT MODIFICATIONS: none
Impacts
Project 1. Microscopy images depicted the chorion surface as characterized by a matrix of ridges and micropylar processes in a ring around the margin of the operculum. Observations of oviposition sites showed a scab formed where the ovipositor penetrated the chorion, and at sites penetrated by the probe. These formations appeared to be the result of fluids from inside the egg leaking out, drying, and hardening after oviposition or probe perforation, suggesting that the response was not due to substances secreted by the parasitoid. Further, no open wounds or holes were seen to increase the possibility of insecticides entering parasitized eggs. Project 2. A pocket-size scouting decision aid was developed that provides the new dynamic threshold, i.e., changes with crop maturity, recommended sampling procedures, and sizing holes to assist users in selecting the correct sized bolls for sampling. Copies of the guide were distributed to cotton growers, independent crop consultants and growers throughout the southeast region. Project 3. BMSB was first found on R1 growth stage soybean in Culpeper County on August 3, and was also detected in Accomack, Augusta, Caroline, Clarke, Gloucester, Loudoun, Middlesex, Northampton, Rockingham, Stafford, and Westmoreland, for a total of 12 counties. When present, the mean number of stink bugs per 15 standard sweep net sweeps ranged from 1 to 12. Field cage data (seed number, weight and quality) are still being analyzed.
Publications
- Bacheler, J., D.A. Herbert, J. Greene, P. Roberts and E. Blinka. 2010. Scouting for stink bug damage in southeast cotton: description and use of a pocket scouting decision aid. Virginia Coop. Ext. Publ. 3005-1445.
- Koppel, A., D.A. Herbert and E.W. Westbrook. 2010. Using microscopy to assess chorion structural integrity and parasitoid oviposition sites on stink bug (Hemiptera: Pentatomidae) eggs. Microscopy Microanalysis. doi: 10.1017/S1431927610093906
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Progress 10/01/08 to 09/30/09
Outputs
OUTPUTS: Laboratory bioassays and field trials were conducted to evaluate the efficacy of selected organophosphate, pyrethroid, and neonicotinoid insecticides, as well as a chitin inhibitor, novaluron, against two common stink bug pests in Virginia, the green stink bug, Acrosternum hilare (Say), and the brown stink bug, Euschistus servus (Say). Additional experiments were conducted to evaluate the toxicity, feeding preference, repellency, and field efficacy associated with the organic insecticides azadirachtin, pyrethrins, and spinosad. Laboratory toxicity bioassays were conducted using treated green bean pods. The conventional pyrethroid lamda-cyhalothrin was included for comparison. A regression model was developed to predict the fight activity of A. hilare using data on the number of adults collected in a single black light trap located in Painter, VA, in the 18-yr period from 1990 to 2007. Eighteen initial weather variables, including cumulative precipitation over different time periods, mean monthly precipitation and days-below-freezing from January to April, and mean monthly temperatures from December to April were tested in developing the regression model. PARTICIPANTS: Katherine Kamminga, Louisiana State Univwersity, Department of Entomology; Tom Kuhar, Virginia Tech, Department of Entomology, ESAREC; Amanda Koppel, Virginia Tech, Department of Entomology, TAREC; Sean Malone, Virginia Tech, Department of Entomology, TAREC; Carlyle Brewster, Virginia Tech, Department of Entomology, Blacksburg, Virginia; Jeremy Greene, Clemson University, Department of Entomology, Soils and Plant Sciences TARGET AUDIENCES: Growers, Crop Consultants, Extension Agents, Researchers PROJECT MODIFICATIONS: This project is progressing well with plans to complete two additional extension publications and one scientific journal article before the end of the next reporting period.
Impacts
Green bean dip bioassays revealed differences in insecticide susceptibility between the two species. A. hilare adults were highly susceptible to all pyrethroids tested, the organophosphates except acephate, and the neonicotinoids except acetamiprid. A. hilare nymphs were also susceptible to all pyrethroids tested. In general, the neonicotinoids, dinotefuran and clothianidin, were toxic to A. hilare, whereas thiamethoxam and acetamiprid were toxic to E. servus. In field trials in soybean, the neonicotinoids, dinotefuran, imidacloprid, and thiamethoxam were efficacious and, in general, performed comparably to the organophosphates and pyrethroids. These results indicate that neonicotinoid insecticides offer an alternative to growers for managing stink bugs that may fit with integrated pest management programs where conservation of natural enemies is a consideration. In the trials with organic insecticides, A. hilare adults and nymphs were most susceptible to lamda-cyhalothrin and to pyrethrins-spinosad tank mixes. E. servus adults were susceptible to lamda-cyhalothrin, spinosad, and all tank mixes, whereas E. servus nymphs were susceptible to lamda-cyhalothrin only. Feeding preference tests using insecticide-treated tomatoes and counting the number of feeding stylet sheaths on fruit after 24 hours showed that tomatoes treated with either azadirachtin, pyrethrins, or tank mixes had fewer numbers of stylet sheaths than the control, whereas treatment with spinosad alone did not. In filter paper repellency tests, both E. servus and A. hilare were repelled by pyrethrins and exhibited no response to azadirachtin. E. servus was attracted to spinosad in comparison with a water-treated control; however, A. hilare displayed no response. In field efficacy trials, each of the organic insecticides reduced the number of stink bugs in soybean, for up to 2 days after treatment; however, none of the insecticides reduced stink bug damage to fruit in tomatoes even after multiple applications. With the black light trap catch data, mixed (backward and forward) stepwise regression analysis showed that a two-variable model using days-below-freezing from January to April and mean monthly precipitation from January to April was adequate for predicting the seasonal mean weekly number of A. hilare adults in the trap. Validation of the model using five independent black light trap data sets resulted in a strong correlation (r = 0.98) between observed and predicted mean weekly number of A. hilare adults caught in traps. Three peaks in fights of A. hilare adults were observed when mean trap catch was plotted over time for the 18-yr period. Peaks occurred at 319, 892, and 1,331 Degree Days from 1 January. Based on known developmental rates, the first peak was attributed to overwintered adults, the second to first-generation adults, and the third to a second generation of adults. This research suggests that A. hilare undergoes two complete generations in Virginia. Cumulative trap catch estimated from the 18-yr mean trap catch showed that 10, 50, and 90 percent of the total seasonal catch should occur by 153, 501, and 1,066 Degree Days.
Publications
- Kamminga, K.L., Herbert, D.A., Jr., Kuhar, T.P., Malone, S., and Doughty, H. 2009. Toxicity, feeding preference, and repellency associated with selected organic insecticides against Acrosternum hilare and Euschistus servus (Hemiptera: Pentatomidae). J. Econ. Entomol. 102: 1915-1921.
- Kamminga, K.L., Herbert, D.A., Jr., Kuhar, T.P., Malone, S., and Koppel, A. 2009. Efficacy of insecticides against Acrosternum hilare and Euschistus servus (Hemiptera: Pentatomidae) in Virginia and North Carolina. J. Entomol. Sci. 44: 1-10.
- O'Berry, N., Faircloth, J., Jones, M., Herbert, D.A., Jr., Abaye, A.O., McKemie, T., and Brownie, C. 2009. Differential responses of cotton cultivars when applying mepiquat pentaborate. Agron. J. 101: 25-31.
- Toews, M.D., Blinka, E.L., Van Duyn, J.W., Herbert, D.A., Jr., Bacheler, J.S., Roberts, P.M., and Greene, J.K. 2009. Fidelity of external boll feeding lesions to internal damage for assessing stink bug damage in cotton. J. Econ. Entomol. 102: 1344-1351.
- Herbert, D.A., Jr., Blinka, E., Bacheler, J., Van Duyn, J., Greene, J., Toews, M., Roberts, P., and Smith, R. 2009. Managing Stink Bugs in Cotton: Research in the Southeast Region. VCE Publ. 444-390.
- Kamminga, K., Herbert, D.A., Jr., Malone, S., Kuhar, T.P., and Greene, J. 2009. Field Guide to Stink Bugs of Agricultural Importance in the Upper Southern Region and Mid-Atlantic States. VCE Publ. 444-356.
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Progress 10/01/07 to 09/30/08
Outputs
OUTPUTS: Three objectives were addressed relating to improve management of stink bug pest species. Laboratory bioassays and field trials were conducted to evaluate the toxicity of selected conventional and organic insecticides against Acrosternum hilare (the green stink bug) and Euschistus servus (the brown stink bug) nymphs and adults. With organics, additional studies were conducted to evaluate non-lethal effects, like feeding preference and repellency. And finally, work was completed to assess the potential of using black lights to aid in predicting populations of A. hilare adults. Only the blacklight project will be reported. A climate-based model to predict abundance of Acrosternum hilare (Say) adults was developed using weekly blacklight trap catch data from 1990-2007. Eighteen initial weather parameters including cumulative precipitation over different time periods, days below freezing, and average monthly temperatures from December to July were tested. PARTICIPANTS: Katherine Kamminga, PhD student, Department of Entomology, Virginia Tech; Thomas Kuhar, Department of Entomology, Virginia Tech; Carlyle Brewster, Department of Entomology, Virginia Tech; Randy Huckaba, Dow AgroSciences; Virginia Agricultural Council TARGET AUDIENCES: growers, agricultural extension agents, crop consultants, ag industry PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Least squares regression showed that two parameters were the most predictive, mean monthly precipitation from December to March and number of days below freezing, and resulted in a significant model [y = 1.13 + 0.017 (days below freezing) - 0.107 (mean monthly precipitation December to March)] (F=6.27; DF=2, 14; P=0.014). The model was validated by correlating five independent data sets (the observed) to predicted weekly trap catch. The correlation was significant with an R-square of 0.96 (F=74.36; DF=1,3; P=0.003). Mean trap catch over the 18 years, plotted over time, showed three distinct annual peaks. To evaluate these patterns, degree days (DD) were calculated using the modified sine wave method. The peaks occurred at 195, 768, and 1206 DD from the biofix (sustained trap catch). In accordance with known developmental rates, the first peak was attributed to overwintered adults, the second to first generation adults, and the third to second generation adults. Cumulative trap catch estimated from the 18-year mean showed that 10, 50, and 90 percent of the total seasonal catch should occur by 153, 501, and 1066 DD, respectively. In summary, results of this work indicate that weather data are useful in predicting A. hilare activity and relative abundance at black light traps. Information using cumulative trap catch and calculated degree days could be useful in helping design and implement field scouting programs, and to help determine periods of highest risk as well as when programs can begin to relax monitoring efforts. The results of this work have also provided fairly clear evidence that A. hilare undergoes two complete and a partial third generation in Virginia.
Publications
- No publications reported this period
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Progress 10/01/06 to 09/30/07
Outputs
OUTPUTS: The first objectives were to determine the species composition of stink bugs attacking crops in eastern Virginia, and to compare insect sampling techniques. A survey of stink bug species was conducted in commercial soybean and cotton fields in 21 eastern Virginia counties. Fields were sampled bimonthly from early June through September using two techniques, a 38 centimeter diameter sweep net (25 sweeps/sample) and a 0.91 meter long beat sheet (1.82 row-meters/sample). On each field visit, 20 samples were taken with each technique in a Z-shaped pattern across the field. Plant growth stage was recorded and all stink bug adults and nymphs were counted, collected and identified to species. The second objective was to evaluate blacklight traps for monitoring stink bug populations. Nine standard 15-watt blacklight traps located adjacent to cotton, soybean, and/or tomato fields in six eastern Virginia counties were monitored from early June through September. Catch data collected
from 1990 to 2006 from a single trap located at the Virginia Tech Eastern Shore Agricultural Research and Extension Center in Painter, VA were also evaluated. Mean monthly temperatures and rainfall totals from December to July and total days below freezing for each year were analyzed against total stink bug trap catch using the stepwise forward predictor model.
PARTICIPANTS: Katherine Kamminga, PhD student, Department of Entomology, Virginia Tech Amanda Koppel, PhD student, Department of Entomology, Virginia Tech Thomas Kuhar, Associate Professor, Department of Entomology, Virginia Tech Sean Malone, Research Specialist, Tidewater AREC, Virginia Tech
TARGET AUDIENCES: Virginia Cooperative Extension Ag Agents Soybean, cotton and tomato growers in Virginia and the mid-Atlantic Agribusiness Private crop consultants Ag-related Agencies (e.g., VA Dept Ag and Consumer Services, VA Dept Conservation and Recreation)
Impacts
The stepwise forward predictor model showed that the combination of seven environmental parameters (one, the average temperature for December; two, the average temperature for March; three, the average temperature for April; four, the average temperature for June; five, the average total precipitation for December; six, the average total precipitation for May; and seven, the average total precipitation for June) were highly related to total number of Acrosternum hilare adults captured in blacklights (P = 0.0004, Rsquare = 0.91). This indicates that these weather factors may be useful for predicting relative pest pressure by this important stink bug pest species. Trap catch data for 2007 and 2008 will be used to validate this model. In the stink bug species survey, a total of 1,524 stink bug adults and nymphs were collected and identified. Seven species were identified including Euschistus servus, E. tristigmus, E. variolarius, A. hilare, Thyanta custator accera,
Oebalus pugnax, and Podisus maculiventris. The two most common species were A. hilare, the green stink bug with 437 adults and 547 nymphs, and E. servus, the brown stink bug with 314 adults and 141 nymphs. More stink bugs were caught in soybean than cotton for all species recorded (P = 0.0004). In cotton, the beat sheet was more effective than the sweep net in sampling E. servus (mean = 0.0442 and 0.0125 per beat sheet and sweep net sample, respectively). Both techniques were equally effective in sampling A. hilare (mean = 0.0308 and 0.0313 per beat sheet and sweep net sample, respectively). In soybean, the sweep net was more effective than the beat sheet in sampling both species (mean = 0.1524 vs. 0.2340 E. servus per sample using beat sheet and sweep net, respectively, and mean = 0.0668 vs. 0.3519 A. hilare using the respective techniques. Plans are underway to develop three deliverables from this research. Results of the stink bug species survey have provided important information
as to which species are attacking Virginia crops and the relative abundance of each. This is a necessary first step to developing pest management programs. The comparison of insect sampling techniques (sweep net and beat sheet) provided critical information for developing recommendations for growers. Both the species identification and sampling information will be delivered to clientele via winter production meetings, and via extension publications. Second will be a predictor of potential risk to stink bug infestations for local soybean, cotton and tomato growers based on blacklight trap catch numbers and the weather patterns identified as being highly related to trap catch. These predictions can be posted to clientele via the existing delivery system, the Virginia Ag Pest Advisory, which posts weekly pest alerts and updates during the growing season in emails to about 400 recipients across the Mid-Atlantic States. A final goal is to develop a hand-held photo guide for distinguishing
stink bug pest species with high quality color images of eggs, nymphs, adults and images of typical stink injury to crops.
Publications
- Blinka, E.L., J.W. Van Duyn, D. A. Herbert, Jr., S. Malone, P.M. Roberts, J.R. Bradley, and J. Bacheler. 2007. Associations of external bug-induced boll damage with internal damage, lint yield and quality. Proc. Beltwide Cotton Confs. 1129-1134.
- Herbert, D.A., Jr., and S. Malone. 2007. Insect Pest Management in Virginia Cotton, Peanut and Soybean 2006. Virginia Cooperative Extension Publ. 444-380.
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