Reducing synthetic chemical inputs and tillage can have numerous benefits in agroecosystems, such as building soil health, promoting biodiversity, and reducing environmental effects of pesticides. In addition to these benefits, low-disturbance cropping systems may also enhance predator communities and the potential for predators to suppress pests. While tillage can kill or disrupt invertebrates, planting a winter cover crop may help sustain invertebrate communities by providing habitat and nutritional resources. This work will complement an ongoing study investigating soil and cover crop management practices on invertebrates within a reduced-tillage organic cropping systems experiment. We will measure crop damage from invertebrates, characterize invertebrate communities, and measure predation rate of insects in corn plots undergoing four different crop management strategies. This work will identify the contributions of key predators within these cropping systems and allow us to understand which management practices most effectively enhance predation and suppress damage from pests.
The purpose of this project is to investigate the impacts of organic cover crop-based reduced tillage cropping systems on beneficial and pest insect communities and biological control potential. As market demand for organic grain increases in the United States, there is a greater need for approaches that facilitate productivity and profitability. In this project, I am investigating the effects of cover crops and reduced tillage on insect pests and slugs, their predators, and biological control potential associated with these predators in an organic agronomic cropping system. Organic growers face tradeoffs between tillage for weed management and soil quality. Understanding how management practices, including tillage and the use of cover crops, affect pests and the potential for predators to control these pests will enable growers to maximize productivity and profitability.
Management of invertebrate pests in organic systems relies heavily on preventative cultural methods such as strategically adjusting planting date, tillage, crop rotation, and on natural processes such as biological control. Benefits of biological control are maximized through understanding factors limiting or promoting the establishment of predators, the likelihood that predators in fields feed on prey within those fields, and the relationship between predator abundance and diversity on levels of damage incurred from pests. It is also beneficial to know which predators are the greatest contributors to biological control. Most predatory insects are actually omnivores, and require plant-based resources such as pollen or nectar in their diet. Consequently, although predators may be present in the field, they may not necessarily be feeding on pests, especially if other food resources, such as pollen and nectar, are more abundant. My project will provide valuable information to help formulate recommendations for organic producers on how to maximize predators and predation within their fields to reduce pest damage and facilitate more reliable organic feed and forage production.
My research supports two of SARE’s key themes for sustainable agriculture. First, this project will promote the reduction of environmental and health risks in agriculture and improve productivity by providing alternative strategies to pest management without the use of pesticides or other synthetic inputs. Second, the facilitation of biological control of pests and organic production will increase net farm income by suppressing damage and yield loss from insect pests. Since the Northeast region has a relatively high concentration of organic farms, improvements for organic productivity will directly benefit farmers in the Northeast. Through the development of extension resources, organic producers and extension educators will have free access to information produced by this research.
Objective 1: Characterize and compare pest and beneficial soil-associated invertebrate communities in four organic corn production systems designed to reduce tillage and incorporate cover crops
Objective 2: Assess pest damage to corn in four organic corn production systems designed to reduce tillage and incorporate cover crops
Objective 3: Evaluate biological control potential of predatory invertebrates in four organic corn production systems designed to reduce tillage and incorporate cover crops
Objective 4: Communicate results from this and other research projects focused on reducing tillage and incorporating cover crops through presentations, informational handouts, and presentations at scientific and grower conferences.
Objectives 1-3 rely on sampling and data collection during the crop production season and this project builds upon an existing project investigating the effects of cover crops and reduced tillage on soil nutrient cycling, agronomic performance, weed management, and early-season invertebrate pests. Field data collection is now complete for most objectives but samples are still being processed in the lab for Objective 1. Additionally, some field collection will continue for Objective 3. Objective 4 is in progress and will continue to develop as I analyze data for this project.
This experiment has taken place within the context of the ongoing Reduced-Tillage Organic Systems Experiment (ROSE) at the Russel E. Larson Agricultural Research Center near Rock Springs, PA. This ongoing project is investigating the effects of cover cropping, reducing tillage, and manure management on agronomic production, weed management, soil nitrogen dynamics, and early-season invertebrate pests in an annual organic feed grain system. We have expanded upon this project by adding a new focus on beneficial invertebrates and biological control potential.
The crop rotation in the ROSE consists of corn (Zea mays), soybean (Glycine max), and spelt (Triticum spelta) in a 3-year rotation (see attached diagram).We will measure pest and beneficial insects, spiders, and slugs during the corn phase of the rotation. Because this is a full-entry experiment, all crops in the rotation are present in each year of the experiment. Each cropping system is replicated four times with plots measuring 9 meters (30 ft)) by 49 meters (160 ft).
The four cropping systems include:
1) hairy vetch (Vicia villosa) and triticale (Triticale hexaploide) cover crop mixture – terminated by roller crimper – no-till planted corn – corn harvested for silage
2) hairy vetch and triticale cover crop mixture – terminated by moldboard plowing – corn – interseeded with a forage radish (Raphanus sativus), orchard grass (Dactylis glomerata), and annual ryegrass (Lolium multiflorum) cover crop mixture – corn harvested for grain,
3) red clover (Trifolium pratense) and timothy (Phleum pratense) cover crop mix – terminated by moldboard plowing – corn – corn harvested for silage
4) red clover (Trifolium pratense) and timothy (Phleum pratense) cover crop mix – terminated by moldboard plowing – corn – interseeded with a forage radish (Raphanus sativus), orchard grass (Dactylis glomerata), and annual ryegrass (Lolium multiflorum) cover crop mixture – corn harvested for grain
Cover crops are typically terminated in mid to late May and planting occurs in early June. In System 1, where corn is planted no-till, preceding cover crops are terminated by rolling with a roller-crimper to form a mulch on the soil surface. In systems 2, 3, and 4, we use moldboard plowing to terminate the cover crops and prepare the seedbed for planting. Short planting windows between cash crop harvest in the fall and reduction in temperatures can make establishing cover crops challenging in the fall. The cover crop treatments in ROSE were chosen to overcome this short planting window and improve cover crop benefits. In Systems 2 and 4, we interseed cover crops at the V5 stage of corn in approximately mid-July, allowing corn to be harvested later for grain instead of silage without compromising our ability to establish a cover crop for that winter. Additionally, in Systems 3 and 4 where corn is preceded by red clover and timothy, the red clover and timothy mix are seeded into the spelt in early spring, allowing it to establish prior to spelt harvest and giving it a longer growing season than the hairy vetch and triticale mixture that is established after spelt harvest in the other two systems. We harvest corn for silage in late September or early October for Systems 1 and 3 and late October for grain in Systems 2 and 4. Comparison of these four cropping systems allows us to assess effects of the species and management of preceding cover crops, timing of tillage, and mid-season interseeding of cover crops on pest establishment, predator establishment, and predation by these beneficial predators.
We have used multiple sampling methods to characterize pest and beneficial soil-dwelling arthropod communities. We use pitfall trapping to characterize the general arthropod community. We will place two pitfall traps consisting of a plastic deli container buried level with the soil surface in each treatment plot and filled with ethylene glycol as a killing agent. Traps were left open for 72 hours. Arthropods have been removed from traps and are being identified. Pitfall sampling occurred three times per season: two weeks prior to cover crop termination, two weeks after corn emergence, and four weeks after interseeded cover crop emergence. These three time points will allow us to test effects of the preceding cover crop on arthropods, measure whether these populations are retained after cover crops are terminated and corn is planted, and to measure whether the addition of interseeded cover crops mid-season helps re-establish predators that may have been less abundant after corn planting.
To assess effect of management system on seedcorn maggot populations, seedcorn maggot emergence traps were placed at the soil surface shortly after corn emergence to capture emerging adult flies (Hammond 1990). Traps consist of a plastic window box (1.0 m by 0.3 m) with a hole cut in the base that is fitted with a quart size mason jar. The traps are placed base side-up so that as flies emerge from the soil, they will move towards sunlight visible through the jar and be trapped by a mesh funnel in the opening in the jar (Hammond 1990). Jars were removed and emptied weekly from corn emergence until true leaf formation (V2). All arthropods caught were returned to the lab and are being identified.
Early-season pest damage was assessed through visual observations. Areas with missing seeds underneath seedcorn maggot emergence traps were dug up to look for maggot feeding damage. Damage from other early-season pests will be measured on a 5.3 meter (17.5 ft) transect in each plot. Plants were examined for damage from a variety of plant-feeding pests common early in the season including: slugs (Gastropoda), cutworms (Lepidoptera: Noctuidae), billbugs (Sphenophorus aequalis), and other chewing insects. In addition to categorizing damage, the amount of damage per plant was rated on a 0-4 scale with 0 indicating no damage, 1 indicating 1-25% damage, 2 indicating 26-50% damage, 3 indicating 51-75% damage, and 4 indicating greater than 76% of a plant damaged. Plant populations were also recorded along this transect.
European corn borer has two flights in central Pennsylvania (Bohnenblust and Tooker 2010). Damage from European corn borer was assessed in early September after the conclusion of the second generation’s flight to provide a cumulative measure of damage over the entire season. Twelve plants per plot were collected and examined for boring tunnels on corn stalks or feeding damage on the corn ear from European corn borer or corn earworm, another common pest of corn in Pennsylvania. Any larvae found in tunnels or on the ear were collected and identified. Additionally, five randomly selected transects of 20 plants each were visually inspect for damage from fall armyworm. Any larvae found were collected and identified.
Biological control potential was measured in three ways. To measure predation rate, five waxworm larva (Galleria mellonella) were attached to index cards to serve as sentinel prey. Baited index cards were surrounded by a trap constructed from 19-gauge mesh hardware cloth and covered with a clear plastic lid to allow entry by invertebrate predators but exclude vertebrates, such as mice, and rain. One day prior to each pitfall event, four baited sentinel cards were placed in each plot for 24 hours. After 24 hours, the cards were collected and the proportion of sentinel prey fed upon was determined.
To record the relative contribution of different predator taxa to predation, we placed an infrared camera above each sentinel bait card to record feeding events for the 24 hour-period that cards are in the field each time that sentinel predation assays occur. We are currently reviewing video footage from 2017 to identify predators and record the amount of feeding by each predator, allowing us to determine frequency of predation by specific predators and which are likely to make the greatest potential contribution to suppression of pest populations.
To reinforce our understanding of predator activity within the field and connect it to the overall invertebrate community, we marked sentinel caterpillars with a protein mark and test predators for this mark. This was done using diluted egg white sprayed onto waxworms attached to two of the four sentinel bait cards used in each plot. Predators were collected from two additional pitfall traps buried adjacent to the marked cages that had no killing fluid but instead were lined with an adhesive card. Predators were identified, removed from adhesive cards, and analyzed for the protein that we used to mark the caterpillars using enzyme-linked immunosorbent assay (ELISA) techniques. This assay use antibodies to detect specific proteins, to determine whether predators caught in pitfall traps have fed upon our sentinel prey. This technique was carried out in collaboration with Dr. James Hagler at the USDA Arid Land Agricultural Research Lab in Maricopa, AZ, who is the developer of this method. Predators collected in 2017 were brought to Arizona and assayed in Fall 2017. Additional predators will be collected and assayed at the USDA lab in 2018, as well.
Through this research, we will learn which predator groups are making the greatest contribution to predation in each system, depending on time of year and habitat created by those systems. By evaluating the predation occurring within different cropping systems, we can better determine how tillage and cover cropping practices enhance or detract from insect predation. Additionally, by identifying main contributors to predation, we can gear conservation efforts through management practices towards these key predators.
To most effectively benefit farmers, the information from this research project must be shared in an accessible fashion and with grower priorities in mind. I am summarizing information learned from this project on the benefits and trade-offs in cover crop management and approach to tillage reduction on predator conservation and biological control. Outreach materials will include factsheets that can be disseminated to farmers, extension educators, and industry representatives associated at extension events and as pdfs electronically through Penn State Extension to provide guidance on enhancing pest management through the conservation of naturally-occurring predators. An online fact-sheet on seedcorn maggot biology and management has been completed and can be accessed here: http://ento.psu.edu/extension/factsheets/seedcorn-maggot. An additional fact sheet is in progress outlining the conservation of natural enemies common to corn fields in Pennsylvania, such as spiders and ants.
Through the larger ROSE project, which includes research at the research station and on three organic farms, we have ongoing opportunities to participate in outreach and extension with organic producers and other stakeholders. We will host our third annual advisory board meeting in February 2018 for farmers and stakeholders involved with ROSE that features discussions on research results, technical details of management, and proposed future directions. We design the advisory board meeting to maximize farmer contribution and peer-to-peer information sharing. We host or co-host field days at the Penn State research station and on our collaborating growers’ farms, allowing us four opportunities in each year to interact with producers in a tour-based setting. We have welcomed visitors at the project sites in the past, allowing us to extend knowledge to farmers that may not be directly related to the project. Events hosted by our project team will include post-event evaluation surveys to obtain directive feedback from participants about knowledge attainment from the event, their intention to implement new practices, and their information content needs, including preferred methods and context for receiving this information
We were able to share information on the broad ROSE project at the Pennsylvania Association of Sustainable Agriculture’s annual conference last year, extending our reach to a wider audience and allowing us to benefit more producers interested in sustainable agriculture. This year, we will present an arthropod-specific poster at a new organic research poster session hosted at the PASA conference.
Data from this objective is still being collected. Field samples from pitfall traps have been collected but arethropods are still being identified in the lab.
Flies collected in emergence traps to study seedcorn maggot populations have been processed but are awaiting confirmation of their identification. Thus, this data cannot yet be presented.
In 2017, early season damage averaged 1 on my 0-4 scale of severity, indicating that less than 25% of each plant was damaged. The most common category of damage was slug damage, with 90% of plants affected. This was unsurprising, as it was a fairly cool and wet spring in Pennsylvania, which is favorable to slugs. There were no significant differences in severity of damage or prevalence of slug damage between the four cropping systems assessed. There was an increase in prevalence of damage from chewing pests in System 1 (45% of plants), which is preceded by hairy vetch and triticale and then planted no-till relative to the three systems which are tilled before planting (about 10% of plants affected in each).
Late season caterpillar pressure was fairly low, relative to previous years at this research site. European corn borer damage (Ostrinia nubilalis) was nearly absent in 2017 with only 1 tunnel found in all of the plants assessed. Fall armyworm (Spodoptera frugiperda) was also fairly sparse and corn earworm (Helicoverpa zea) was less prevalent than in past years at this site, as well. With the low populations, no effects of cropping system were observed on caterpillar populations or damage.
Predation, as measured through sentinel bait cards, increased after corn planting in 2017, with the lowest rates occurring before cover crops were terminated and higher rates on the later two sampling dates. There were no differences among cropping system at any of the three dates.
Camera footage is still being processed so identification of key predators contributing to feeding on sentinel bait cards cannot yet be presented. Gut content analysis of predators that fed on protein-marked sentinel prey were assessed using ELISA. Of 540 arthropods assessed, only 3 yielded positive marks. All three of these were ground beetles (Coloeptera: Carabidae). Unfortunately, the low number of positive marks limits conclusions that can be drawn. Re-evaluation of methodology may be necessary to enable successful use of these techniques to study predation in the field.
Education & Outreach Activities and Participation Summary
An online fact sheet outlining the biology and management of seedcorn maggot was completed in August 2017. This fact sheet can be accessed here: http://ento.psu.edu/extension/factsheets/seedcorn-maggot
I presented a description of research I was conducting at the Penn State Research Farm, including my SARE research, to a medium-sized audience (40) of extension educators working in field and forage crops at Penn State and also to a group of visiting farmers and agricultural educators from South America (15 people). Most information was presented orally but I used the following poster as a backdrop for my presentation: 27June2017-Extension-Poster
I gave a tour of our research site and a description of my research to a visiting farmer and his grandson from Massachusetts.
I presented preliminary research findings at three poster sessions and two research conferences in 2017.
I assisted with two separate workshops related to identification and conservation of predatory arthropods in farm fields. The first occurred at the Penn State Student Farm to educate local residents and gardeners on improving the health of their soils and conserving beneficial arthropods, including soil-dwelling arthropods. The second was a workshop focused on soil health presented to over 100 farmers, industry representatives, and extension educators attending the annual Penn State Agronomy Diagnostic Clinic. My portion of the workshop focused on predators living in or on the soil and how soil health practices affect them. Both workshops relied on preliminary lessons learned through my SARE research on soil-dwelling pests and predators.
Upcoming activities will include two poster sessions in early 2018 including summarized 2017 herbivory results, as well as a presentation at a research conference in March 2018 on predation results. I also plan to present at another research conference in November 2018. Analysis and summary of results is ongoing with the intention of publishing journal articles and preparing an additional fact sheet.