Progress 09/01/13 to 08/31/16
Outputs
Target Audience:University scientists, USDA employees, graduate and undergraduate students, vegetable growers Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?A postdoctoral scientist, Laura Ingwell, was trained in areas related to extension entomology and agriculture. These include attending theLocal Food Summit (2016) in Indianapolis. This included participationin discussions around food availability, security and the Farm to School program. Also, networkingwith local growers, food hubs and community gardeners. Two other workshops were attended for professional training on campus at Purdue University:Building an Effective Extension Program (2016),Working with Print and Television Media (2016) How have the results been disseminated to communities of interest?For each year of this project we have presented the data from this work in talks to scientific audiences at professional conferences. These include the Entomological Society of America (2014: Portland, OR; 2015: Minneapolis, MN; 2015: North Central Branch, Cleveland, OH; 2016: Orlando, FL). In addition, we have given extension talks to vegetable growers at the Indiana Horticultural Congress on high tunnel biocontrol in each of the past two years (Indianapolis, IN, Jan. 2015 and 2016). Dissemination to growers was also accomplished via 4 extension publications on using predators and parasitoids in high tunnels and participation in field days where growers and other groups visited experimental high tunnels at the Throckmorton-Meigs research farm in Lafayette, IN in 2014 and 2015. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Despite stagnant growth in many U.S. agricultural sectors, the last decade has witnessed an explosive rise in demand for locally grown produce. This trend is driven by increasing public awareness of the lack of transparency along the food supply chain linking farm-to-fork, including both the source of and production methods used to grow food. Unfortunately, cold weather constrains crop production for much of the year, except in southernmost U.S. states, preventing the vast majority of growers from meeting demand and thereby limiting farm profitability. One of the leading solutions to this dilemma of seasonality in temperate climates is to employ high tunnels, a form of protected agriculture that aids in season extension by creating a more favorable microclimate using trapped solar heat. Our research was designed to test the utility of biocontrol in high tunnel systems where insecticide applications are more challenging. We identified the specific predators that work better in tunnel systems for managing aphids and other greenhouse pests. We also determined effects of different management styles on predator retention for use by diversified vegetable growers. Objective #1: Quantify the impacts of high tunnel screening, semiochemicals, and flowering plant availability on predator dispersal and pest consumption. We conducted a two-year experiment in 6 high tunnels at Purdue's Meigs horticultural research farm. Two of these tunnels were controls with open sides; two had screening on the sides and end walls to retain released predators; and two included a flowering plant + volatile attractant treatment, also in an attempt to reduce emigration of enemies released. For the screen treatments, a fine mesh screen with a pore size of 0.18 mm2 (100% polyolefin, LS EcoNet 4040; Svensson, Dist. By Hummert Int'l, St. Louis, MO) was used to cover all of the ventilation openings in the tunnels. The mesh size was chosen to exclude aphids and whiteflies while retaining the smallest predator included in our study. This screen is not thrips-proof; the mesh size required would reduce airflow to unacceptable levels and lead to plant damage. We tested four different predators as augmentative releases in succession. These included lady beetles (Hippodamia convergens), lacewings (Chrysoperla carnea), minute pirate bug (Orius insidiosus), and spined solider bugs (Podisus maculiventris). These species were chosen because, collectively, they attack a wide-range of pest taxa that we expected to encounter on crops; namely caterpillars, aphids, thrips, and mites. Stink bugs tend to predominantly feed on caterpillars, whereas pirate bugs, lady beetles, and lacewings are major consumers of the remaining greenhouse pests. Predators were purchased from commercial insectaries (Rincon-Vitova Insectaries, Ventura, CA USA; International Greenhouse Company, Danville, IL USA; Beneficial Insectary Inc., Redding, CA USA). Release rates for each predator were as follow: stink bugs at 23-30 per tunnel (limited availability), pirate bugs at five per plant, lady beetles at 10 per plant, lacewings at 50 or 100 per tunnel (approx. 1 per 2 plants or 1 per plant). Species were released sequentially to minimize the likelihood of intraguild predation among beneficials. All were in the adult stage upon release and predators were counted daily and recaptured using D-vac sampling after a one week period. Also, habitat use was tracked by determine relative use of different crops (tomato, cucumber, and cut flowers--zinnia and gomphrena). We found that overall lady beetles and soldier bugs performed poorly in high tunnels. These two species either emigrated rapidly or died in these environments before the completion of the one week survey; however, lacewings and pirate bugs were recaptured at a comparatively higher rate. Further, lacewings oviposited eggs on crops and thus seemed capable of establishing a population in these environment. This was not observed for the other predators. Surprisingly, tunnel screening had only minor benefits for retaining predators and only in lady bugs and soldier bugs. Because tunnels elevated the summer temperatures we suspect that predator survival was lower in these treatments over longer timescales. A larger mesh size may be more appropriate for predator retention without major increases in temperature or humidity. The combination of induced plant volatiles and flowering plants significantly increased the abundance of pirate bugs across both years and appears to be an effective strategy for this group. Relative crop use varied considerably across the four predators. Notably, lacewings placed eggs primarily on lower leaves of tomato plants and tended to avoid upper leaves. This is very important for growers to know because lower leaves are typically pruned and removed from tunnels as the trellised crop grows vertically. As a result, pruning may reduce the efficacy of lacewings as a biocontrol agent. Also, lacewing oviposition was highly sensitive to temperature fluctuations and this caused them to have a lower fecundity in the screened tunnels where temperature was considerably higher than open tunnels. Objective #2: Evaluate the consequences of predator retention treatments for pest population dynamics, pollination, and crop yield. We evaluated aphids, mites, and caterpillars as pests consumed by our released predators. Also, we tracked tomato and cucumber yield in tunnels via daily harvesting during the fruiting periods. Interestingly, we found extremely large aphid and mite outbreaks in screened tunnels during both years. This was unexpected considering that screens were intended to retain released predators. We suspect that screens exclude colonization by naturally occurring enemies that may do a far better job in suppressing pests than commercially reared ones. This should be evaluated more carefully in the future. It is also notable that cucumber beetles--both striped and spotted--were major pests that severely reduced cucumber yield. By late in the summer many of the plants were infected with bacterial wilt transmitted by the beetles. However, screening was extremely effective in preventing beetles from entering tunnels and thus cucumber yield was far higher in screened tunnels compared with either of the two open treatments. Tomato yield was comparable in the control and flower/volatile treatments, but considerably lower in the screened tunnels. We suspect that this was caused by two factors. First, screening resulted in very large aphid and mite outbreaks that likely reduced yield. Second, screening caused temperature spikes that likely led to fruit abortion, lowering productivity.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Ingwell, L.L., Foster, R., and I. Kaplan. 2015. Biological control in high tunnel agriculture: An effective pest management tool? Entomological Society of America Annual Meeting, Minneapolis, MN. November 15-18, 2015
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
Ingwell, L.L. 2016. Aphid management in winter green production in high tunnels. Vegetable Crops Hotline. Issue 622. Retrieved from https://vegcropshotline.org/article/aphid-management-in-winter-green-production-in-high-tunnels/
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
Ingwell, L.L. 2016. Considerations and suppliers for biological control. Vegetable Crops Hotline. Issue 616. Retrieved from https://vegcropshotline.org/article/considerations-and-suppliers-for-biological-control/
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
Ingwell, L.L. and R.E. Foster. 2016. Augmentation biological control in high tunnels. Vegetable Crops Hotline. Issue 615. Retrieved from https://vegcropshotline.org/article/augmentation-biological-control-in-high-tunnels/
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
R.E. Foster and L.L. Ingwell. 2016. Aphids in high tunnels. Vegetable Crops Hotline. Issue 614. Retrieved from https://vegcropshotline.org/article/aphids-in-high-tunnels/
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Progress 09/01/14 to 08/31/15
Outputs
Target Audience:Vegetable growers, university and USDA scientists Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?One postdoctoral scientist was trained under this project, as well as 3 undergraduate students, 2 from Purdue University and one exchange students from Colombia. How have the results been disseminated to communities of interest?In July 2015 we demonstrated our high tunnel experiment, including the screened and flowering treatments, to a group of 50 fruit and vegetable growers visiting the Meigs-PAC (Purdue Agricultural Center) in Lafayette, Indiana. In addition, a postdoctoral scientists funded on the grant, Laura Ingwell, presented the results of this research to the Horticultural Congress in Indianapolis and at the Entomological Society of America in Portland, Oregon in November 2014. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
During the 2015 growing season we contined the 2nd year of the high tunnel field experiment. Between April and September we conduced at least 6 releases of green lacewings, as welll as multiple releases of Orius insidiosus. Sampling (visual and Dvac) was as in previous summers. In addition, pests were surveyed weekly and compared across the 3 tunnel treatments. As in 2014, cucumber beetles (and thus bacterial wilt) were largely excluded from screened tunnels, but these tunnels also had much higher temperatures compared with open-air controls. Because of this, lacewing mortality was far higher in the screened tunnels, whereas Orius retention was significantly enhanced by the provisioning of cut flowers and herbivore-induced plant volatiles (MeSA).
Publications
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2014
Citation:
Ingwell, L.L., Foster, R., and I. Kaplan. 2014. Predator conservation in protected agriculture. Entomological Society of America Annual Meeting, Portland, OR. November 16-19, 2014
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Progress 09/01/13 to 08/31/14
Outputs
Target Audience: Entomologists in academia and the USDA studying insect pest management in high tunnels. Diversified vegetable growers in Indiana. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? This project has provided training for one postdoctoral scientist, Dr. Laura Ingwell, who has background in insect vector-crop virus interactions. It also provided training for two undergraduate workers who assisted Dr. Ingwell during this project. How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
In the spring of 2014, a postdoctoral scientist was hired to begin work on this project. This spring tomatoes, cucumbers, and cut flowers (zinnias and gomphrena) were planted for transplant into the high tunnels at Meigs horticultural farm. The plantings were a bit delayed due to damage to the high tunnel structures in a tornado the previous fall. After the tunnels were fixed, mesh screening was attached to two of the tunnels, and a new wooden trellis system was constructed to support vertical vining of tomatoes/cucumbers, we initiated the proposed experiments. We tended to have low recapture rates, especially of predaceous stink bugs. Screening tended to greatly increase retention of lady beetles, but this did not affect pest densities. This may have been because of large aphid and mite outbreaks in the screened tunnels. We suspect that the screen excluded naturally colonizing beneficial insects, which induced these outbreaks. Orius was attracted to flowering plant and HIPV tunnel treatments, including both released individuals and naturally occurring ones. Yield per plant tended to be higher in the screened and flower/HIPV treatments compared with the control. This may have partly been due to the fact that cucumber beetles and bacterial wilt were far bigger problems in the control tunnels and killed many of the cucumber plants. Also, we found large differences in temperature. The screened tunnels were 10-20 degrees warmer than the non-screened tunnels, which almost certainly affected both pest population growth and predator survival.
Publications
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