Recipient Organization
PURDUE UNIVERSITY
(N/A)
WEST LAFAYETTE,IN 47907
Performing Department
Entomology
Non Technical Summary
Soybean is a key crop in the U.S., which supplies 35% of the world's production. In 2006, more acres of soybean were harvested in the U.S. (74.6 million) than acres of any other crop, including corn (70.6 million). Soybeans are produced in 31 states and 3 provinces in the eastern, central, and southern U.S and Canada, from Quebec to Florida, and Delaware to Nebraska. Given this large acreage and wide distribution, it is not surprising that soybean continues to suffer from insect pests that impact plant growth, grain quality, and yield. Whether it is a result of accumulated years in soybean production, changes in cropping practices, or global climate change, the distribution and impact of native and established pests is increasing in soybean. The populations of soil pests such as slugs, grubs, and millipedes, and foliar and pod feeders such as bean leaf beetle and stink bugs, are increasing in many regions. The distribution of other insects, such as Dectes stem borer and pyrethroid-resistant Lepidoptera (such as corn earworm), appears to be growing. Producers are encountering insect problems that they have never seen or managed. From a research standpoint, changes in pest distribution and status require greater understanding of pest biology and movement, as well as the development or modification of scouting and control methods. As in many other production systems, invasive species in particular are also an increasing issue in soybean production. In the northern U.S. and eastern Canada, the discovery of the soybean aphid (SBA) in 2000 fundamentally changed soybean insect management. SBA feeding impacts all components of yield; under heavy aphid pressure, yield differences between treated and untreated research plots may reach 50%. Outcomes/Impacts * Obj 2b. Success in classical biological control will reduce populations of, and yield loss from, SBA. A partial success could save producers tens of millions of dollars in control costs alone, with societal benefits of reduced human exposure, reduced non-target impacts from pesticide use, and slower formation of insecticide resistance. A better understanding of North American natural enemies and their conservation will have similar impacts as a partial success in importation biological control. * Obj 2c. The introduction of resistant varieties will reduce grower inputs by protecting yield and reducing outputs for insecticides. As a further result of reducing insecticide use, resistant varieties will lessen human exposure and non-target impacts, and eliminate or slow the formation of insecticide resistance. Management of SBA through the use of aphid-resistant varieties may also manage plant viruses through changes in aphid behavior. Further, host plant resistance is highly compatible with biological, cultural and chemical control of pests, and as such is a key component of soybean IPM programs.
Animal Health Component
(N/A)
Research Effort Categories
Basic
(N/A)
Applied
(N/A)
Developmental
(N/A)
Goals / Objectives
1. Characterize insect-soybean interactions and their impact on plant growth, grain quality, and yield. 2. Develop and validate tactics for management of key soybean insects. Outputs: * Obj 2b. Field releases of one or more species of exotic natural enemies of soybean aphid in participating states/province. Development of protocols to assess the risks and effectiveness of classical biocontrol releases for SBA. Increased understanding of the impacts of native natural enemies on soybean aphid, and how these impacts can be conserved and enhanced. * Obj 2c. Incorporation of aphid resistance into commercially available soybean varieties. Increased understanding of the mechanisms of resistance to SBA and Dectes stem borer. Increased understanding of the interaction between aphid resistance and biocontrol
Project Methods
Objective 2. Develop and validate tactics for management of key soybean insects. Sub-objective 2b. Enhance biological control of soybean aphid, using both conservation of natural enemies and classical biological control releases. [(IL, MN, USDA Beneficial Insect Intro Lab), IA, IN, MI, ON, QC, SD, VA, WI] Importation biological control efforts for the soybean aphid will include further exploration for new (Asian) natural enemies, quarantine evaluation of host-specificity, field and laboratory studies of potential non-target impacts, and release and evaluation of one or more Asian species. Collections will be made in China, Japan, and Korea. Natural enemies will be shipped to quarantine facilities at the USDA Beneficial Insect Unit in Delaware and the University of MN. In quarantine, the host specificity of select natural enemies will be evaluated against a suite of native and introduced aphid species. Non-target studies will include field sampling of native aphids to estimate population size and pre-release natural enemy load. We will develop a set of protocols to guide natural enemy releases and evaluate impact. In brief, we will use field cages to inoculate and increase natural enemy numbers, opening the cages to effect the release. SBA populations will be sampled to monitor the establishment of the natural enemies, and to measure their impact on aphid numbers and crop damage. Research will also focus on conserving and enhancing native and naturalized natural enemies. Work on generalist aphid predators (such as Syrphidae and Coccinellidae), fungal pathogens and parasitoids will continue in many states/provinces. Research will focus on how natural enemies delay or prevent aphid outbreaks, influence the growth of aphid populations between the economic threshold (currently 250 aphids/plant) and the economic injury level (ca. 660 SBA/plant), affect end-of-season dynamics, as well as impact production and survival of the overwintering aphid population. To conserve natural enemies, we will examine intercropping soybeans with other plants (e.g., annual rye), the effects of pesticide applications on the survival and efficacy of natural enemies, and the impact of host plant resistant on natural enemy-SBA dynamics.