2009 Annual Report
1a.Objectives (from AD-416)
The therapeutic approach of killing pest organisms with toxic chemicals has been the prevailing pest control strategy for over 50 years. Safety problems and ecological disruptions continue to ensue, and there are renewed appeals for effective, safe, and economically acceptable alternatives. The overall objectives of this project are to conduct research on the basic biology and ecology of weeds and insect pests and beneficial insects in corn/soybean/wheat production systems and to develop integrated pest management systems and decision aids. Our specific objectives are to:.
1)investigate the behavior and genetics underlying the resistance of corn rootworms to pest management tactics and develop novel pest management technologies for northern and western corn rootworms; .
2)reduce emerging weed and insect problems in corn/soybean and corn/soybean/wheat rotations; and.
3)develop and evaluate cultural, biological control and host plant resistance management tactics for emerging and invasive insect pests of soybean. Attaining the objectives as outlined above will provide farmers with new and refined methods of pest and crop management for improved crop productivity and quality.
1b.Approach (from AD-416)
Our interdisciplinary research brings emerging technological advances and integrated pest management practices together to develop short- and long-term pest management strategies for sustainable agriculture. Our approaches are to characterize the ecology, behavior, and genetics of insect and weed pests in agricultural systems of the northern Great Plains as a basis to:.
1)develop and evaluate resistance management and pest control strategies;.
2)determine pest-crop interactions and pest-landscape relationships to develop sampling/monitoring technology;.
3)optimize management tactics;.
4)assess yield loss potential;.
5)establish action thresholds;.
6)define management zones;.
7)develop risk assessment models; and.
8)improve understanding of the interactions between pest and beneficial insects and impacts of agronomic practices on beneficial insects in corn/soybean/wheat cropping systems. Benefits potentially derived from this research include reduced chemical usage, improved crop production efficiency, better cultural control options for pest management, and the development of integrated pest management systems based upon a better understanding of pest biology and ecology.
Insect and weed pests cause significant economic loss to farmers and foster dependence on pesticides. New pest management tactics are needed that will provide efficacious, economically viable, safe, and environmentally sustainable alternatives to conventional pesticides and that prolong the useful life of existing and emerging management technologies. The overall philosophy of the Crop Protection and Quarantine National Research Program (NP 304) is to develop and implement ecologically-based sustainable approaches to the management of native and invasive insect, mite, and weed pests through a combination of biological, cultural, physical, and chemical methodologies that reduce pest populations to acceptable levels while minimizing impacts on human health and the environment.
The research described in this annual report addresses several high-priority research needs as outlined in this National Program: Integrated pest management systems and areawide suppression (accomplishment “corn rootworm areawide pest management in South Dakota”); Integrated weed management in cropland (accomplishment “impact of crop residue and tillage on weed seedling density”); Establishment of action thresholds (accomplishment “soybean aphid effects on crop yield and quality); Cultural control of insect pests of wheat and insect-vectored disease (accomplishment “essential crop nutrients to reduce yield loss to cereal aphids and aphid-vectored disease); Breeding for host plant resistance (accomplishments “screening maize germplasm for resistance to corn rootworm, identification of soybean lines resistant to soybean aphid, additional soybean lines with resistance to soybean aphid, identification of wheat and triticale lines resistant to bird cherry-oat aphid); Basic biology of pests and natural enemies (accomplishment “status of previously common native lady beetles in South Dakota”). We are obtaining basic biological, behavioral, and ecological knowledge concerning key weed and insect pests as well as beneficial insects in corn/soybean/wheat agricultural systems. This information will be synthesized into ecological concepts as a basis to minimize insect resistance to genetically modified crops and to develop integrated pest management systems and decision aids based upon improved cultural pest control and risk assessment models for decision support. Benefits result from providing farmers with new and refined methods of pest management for improved crop productivity and quality.
Farmers will also see increased pest management efficiency and profitability from reduced pesticide use and from preserved yields that result from new pest sampling and monitoring methodology, precise application of pesticides, strategies for prolonging the use of insect-resistant crops, and the conservation of insects that prey upon crop pests. Benefits include reduced chemical usage and better cultural control options for pest management, leading to integrated production systems based upon a better understanding of agroecological principles.
The body size of rootworms affects their evolution of resistance to Bt corn. An insect’s size affects its ability to survive and reproduce, and is thus important for farmers to consider when designing how much of their Bt corn fields they should plant to a non-Bt refuge. For example, corn rootworms (a severe pest of corn) coming from anti-rootworm Bt corn fields are likely to be relatively small (because Bt harms them but doesn’t kill them) compared to those coming from the non-Bt refuge corn. Research showed that larger females lived longer and produced more eggs than smaller females, and that all females produced more eggs when they were mated to large males. Thus, smaller females and males (like those that have evolved resistance to Bt corn) are less competitive, and this information will be used to predict how fast resistant rootworms will spread through the rootworm population. Seed companies and regulatory agencies use this information to determine how large of refuge areas that farmers need to plant on their fields.
Cover crops and predators suppress the rootworm. Although rootworms are one of the most severe pests of corn, almost nothing is known of the predators that consume this pest beneath the soil. This prompted research that identified more than 17 predator groups that consume rootworms in South Dakota corn fields. Not only are these predators an abundant and diverse form of natural pest management, but their impact on the pest can be improved through the use of cover crops. Planting a winter cover crop (slender wheatgrass), increased predator densities and predation rates, reduced rootworm populations, and decreased root damage compared to conventionally managed corn fields. This research adds insect pest management to the list of benefits derived from planting cover crops, and adds a cost-competitive tool for organic producers and small farmers for whom crop rotation and GM crops are unrealistic or too costly for managing rootworms.
Soybean aphid natural enemies and vegetational diversity: Plant choice matters. The minute pirate bug is an important early-season predator of the invasive soybean aphid (a severe pest of soybean). Numbers of this natural enemy can be increased in soybeans by introducing plant diversity in the form of low levels of weeds or cover crops. The effects of small patches of oats (an important winter cover crop) within soybean fields on predator reproduction and pest suppression were investigated. Contrary to predictions, there were no effects of these non-crop patches on predator performance or pest suppression. Further studies showed that minute pirate bugs do not lay eggs on oats, a critical factor for increasing predator populations. Other grasses (like rye and slender wheatgrass) and legume cover crop species are preferred by pirate bugs, and may be more suitable sources of vegetational diversity. This research helps farmers who use cover crops, and cover crop seed producers, to select covers that promote insect pest management and reduce insecticide inputs.
Soybean aphid predation around the clock. Predators of economically important crop pests are particular in their schedules; some are only active during the day, and some at night. Very little work has been conducted on nocturnal activity of potentially important predators of soybean aphids (a severe pest of soybean). Soybean aphid colonies were observed with regularity over the season every 3 hours for an entire 24-h period. Although most predation events observed occurred during the day, nocturnal observations revealed a group of predators previously undocumented to feed on soybean aphid under field conditions. Understanding which predators are key to suppressing soybean aphid populations is a critical step as farmers implement integrated pest management programs of this invasive pest.
Educating crop advisors on the relationships between soybean aphids and yields. Plant injury caused by the soybean aphid (a serious pest of soybeans) can result in up to 75% yield loss. Soybean growers must effectively manage soybean aphid populations during the growing season to avoid these severe yield losses. Scientists from ARS and South Dakota State University documented strong mathematical relationships between soybean aphid numbers during specific soybean growth stages and the eventual yield at harvest. These experimental results were used to form the basis of a certified crop advisor self-study course and continuing education unit exam. Thus, this advancement in knowledge of soybean aphid – yield relationships was transferred not only to soybean producers, extension agents, and other scientists through professional journal articles and presentations to user groups, but also to certified crop advisors in the form of continuing education units in pest management.
Including winter wheat in a crop rotation reduces herbicide inputs. Producers and scientists are changing their perspective of weed management to include cultural tactics along with herbicides and tillage. Consequently, production systems are reducing the density of the weed community in fields and the need for herbicides. Cultural strategies are being developed to reduce weed community density, improve crop tolerance to weed interference, and reduce weed growth and productivity. One promising practice is to include winter wheat in the corn-soybean rotation. Winter wheat residues preserved on the soil surface can reduce weed seedling density 50 to 70% in corn or soybean compared with tilled systems. Also, weeds common in corn and soybean are not able to establish in winter wheat, thus eliminating weed seed production in that year. The population-based approach to weed management may enable producers to reduce herbicide inputs 30 to 50%.
No-till changes weed emergence patterns over time. A key component of the population-based approach to weed management is understanding the seedling emergence pattern of the weed community. Averaged across four years in a corn-soybean-corn-soybean rotation, more than 80% of weed seedlings emerged between April 28 and June 22 at this location. Seedlings begin emerging two to three weeks later in no-till compared with the tilled treatment. The number of seedlings emerging from a seed source emplaced at the onset of the 4 yr observation declined rapidly across time; density of weed seedlings in the third year was only 10% of the emergence observed in first year (versus 25-30% emergence in the till field after the same duration). The later emergence of weeds in no-till will benefit weed management in cool-season crops such as winter wheat or dry peas by improving crop tolerance to weed interference.
Changing diversity of lady beetles in South Dakota. Lady beetles are beneficial as major predators of agricultural insect pests. However, recent declines in some native lady beetles and increasing abundance of non-native species have prompted calls for a better understanding of the biodiversity of lady beetles across the United States, with South Dakota and New York chosen as pilot states for determining this. A checklist of 79 species of lady beetles was developed for South Dakota, and the list showed 13 new species over those seen in the 1970s. However, a previously common native species, known as the transverse lady beetle, has only been found once in South Dakota since 1979, which is when several exotic lady beetles became more widespread. Current information on lady beetles species is important to practitioners of ecologically-based farming and to environmental managers interested in preserving biodiversity and understanding the impact of invasive species on natural biological control.
Some native lady beetles are being replaced by exotics in the Great Plains. A survey for lady beetles was conducted in farmland and natural areas in South Dakota, North Dakota, Minnesota, and Iowa over 3 years. Four native species collectively comprised 55.8% of 1226 lady beetles sampled, while two exotic species comprised more than one-third of beetles collected. Meanwhile, three previously common, native species were not detected in the survey, indicating that they have become extremely rare within the northern Great Plains. The native lady beetles were most abundant in natural areas like prairies, indicating the importance of these natural habitats in preserving native species. Farmland was dominated by non-native lady beetles, which demonstrates their ability to become prominent members of lady beetle communities in a short amount of time. The results suggest that further studies are needed to determine the impact of these changing lady beetle communities on native fauna. Current information on lady beetle abundance and diversity is important to practitioners of ecologically-based farming and to environmental managers interested in preserving biodiversity and understanding the impact of invasive species on natural biological control.
Improving methods for finding corn with natural resistance to western corn rootworm. Some corn has natural resistance to rootworms (a severe pest of corn), but identifying the genetics that make some corn resistant to insects, and getting these genetics into commercial hybrids planted by farmers isn’t as easy as it sounds. For example, just because a parent corn plant has insect resistance doesn’t mean that this resistance will make it into the hybrids that farmers plant. In collaboration with the University of Illinois and USDA-ARS in Columbia Missouri, it was discovered that the best way to identify corn plants with resistance to rootworms is not to test the parent plant but to test the offspring of the plant after it has been crossed with a special corn plant called a tester. These results will aid corn breeders and entomologists to more efficiently screen corn plants for resistance, and could ultimately result in new corn hybrids that are resistant to corn rootworm which can be grown by farmers.
|Number of Active CRADAs||1|
|Number of the New/Active MTAs (providing only)||6|
|Number of Web Sites Managed||1|
|Number of Other Technology Transfer||2|
Hesler, L.S., Kieckhefer, R.W. 2008. An Annotated and Updated Species List of the Coccinellidae (Coleoptera) of South Dakota. The Coleopterists Bulletin. 62:443-454.
Lundgren, J.G., Hesler, L.S., Tilmon, K.J., Dashiell, K.E., Scott, R.A. 2009. Direct effects of soybean varietal selection and Aphis glycines-resistant soybeans on natural enemies. Arthropod-Plant Interactions. 3:9-16. DOI 10.1007/s11829-008-9053-4.
Hesler, L.S., Petersen, J.D. 2008. Survey for Previously Common Native Coccinellidae (Coleoptera)in the Northern Great Plains. Great Lakes Entomologist. 41: 60-72.
Lundgren, J.G. 2009. Relationships of Natural Enemies and Non-prey Foods. Springer Verlag, Dordrecht, The Netherlands, 453 + xxviii pages.
Lundgren, J.G., Nichols, S.J., Prischmann, D.A., Ellsbury, M. 2009. Seasonal and Diel Activity Patterns of Generalist Predators Associated with Diabrotica Virgifera Immatures (Coleoptera: Chrysomelidae). BioControl Science and Technology. 19(3):327-333.
Anderson, R.L. 2009. Weed seedling emergence and survival as affected by crop canopy. Weed Technol. 22:736-740.
Davis, H.N., Currie, R.S., French, B.W., Buschman, L.L. 2009. Impact of Land Management Practices on Carabids (Coleoptera: Carabidae) and Other Arthropods on the Western High Plains of North America. Southwestern Entomologist. 34(1):43-59.
Anderson, R.L. 2008. Residue management tactics for corn following spring wheat. Weed Technology. 22:177-181.
Anderson, R.L. 2009. Plant Mulches Can Help Weed Management in Ukraine. Zakhyst Roslyn. 13:86-98.
Beckendorf, E.A., M.A. Catangui, W.E. Riedell. 2008. Soybean Aphid Feeding Injury and Soybean Yield and Seed Composition. P. 17-21. In: B. Erickson (ed.) Crops and Soils, Summer 2008. www.agronomy.org.
Kim, K.S., Ratcliffe, S.T., French, B.W., Liu, L., Sappington, T.W. 2008. Utility of EST-derived SSRs as Population Genetics Markers in a Beetle. Journal of Heredity. 99(2):112-124.
Lundgren, J.G., K. Wyckhuys, N. Desneux. 2009. Population Responses by Orius insidiosus to Vegetational Diversity. BioControl. 54(1):135-142. Available online.
Prischmann, D.A., Dashiell, K.E., Schneider, D.J., Eubanks, M.W. Evaluating Tripsacum-introgressed maize germplasm after infestation with western corn rootworms (Coleoptera: Chrysomelidae). J. Appl. Entomol. 133 (2009) 10-20.
Prischmann, D.A., Dashiell, K.E., Hibbard, B.E. 2009. Assessing Larval Rootworm Behavior after Contacting Maize Roots: Impact of Germplasm, Rootworm Species, and Diapause Status. Journal of Applied Entomology. 133:21-31.
Prischmann, D.A., Lehman, R.M., Christie, A.A., Dashiell, K.E. 2008. Characterization of bacteria isolated from maize roots: emphasis on Serratia and infestation with corn rootworms (Chrysomelidae: Diabrotica). Applied Soil Ecology. 40:417-431. Available at www.elsevier.com/locate/apsoil.
Toepfer, S., Haye, T., Erlandson, M., Goettel, M., Lundgren, J.G., Kleespis, R.G., Weber, D.C., Cabrera-Walsh, G., Jackson, J.J., Peters, A., Vidal, S., Strasser, H., Ehlers, R.V., Moore, D., Keller, S., Kuhlmann, V. 2009. A Review of the Natural Enemies of Beetles in the Subtribe Diabroticina (Coleoptera: Chrysomelidae): Implications for Sustainable Pest Management. Biocontrol Science and Technology. 19(1): 1-65.