Ecology and Management of Insect Pests Affecting Vegetable Production in North Carolina

NON-TECHNICAL SUMMARY: The vegetable industry in North Carolina is extremely diverse with more than 30 different crops and 2000 commercial growers (USDA, 2002). Insect pest management in vegetables presents many unique challenges including very low tolerances for insect damage and or contamination, limited availability of registered insecticides, and the public's demand for safe food and environmentally responsible pest management. Insecticides have been the corner stone of insect pest management in vegetables for many years. Because of the market demand for produce free of insect damage and the associated economic risk to growers, chemical insecticides will continue to be an important tool in conventionally grown vegetables into the foreseeable future. It is imperative that biologically based, environmentally sustainable integrated pest management strategies be developed for vegetable crops in North Carolina if the industry is to continue to grow and thrive. Insect management plans founded on the principles of IPM will result in decreased rates of insecticide resistance development, reduced environmental impact, increased efficiency of pest management practices, and improved economic return for producers. Consumers in the U.S. and around the world are becoming increasingly concerned about pesticides from the standpoint of food safety and environmental stewardship. Growers are facing restrictions on pesticide use not only from state and federal agencies but also from domestic and foreign consumers. Insecticide resistance has had a major impact on vegetable production in the U.S. The proper implementation of integrated pest management including the use of scouting to determine pest population levels, economic thresholds to make insecticide application decisions, and non-chemical tactics for managing pests results in reduced pesticide use and decreases the chances of resistance development. Unfortunately, scouting procedures and economic thresholds do not exist for all of the major pests of vegetables in North Carolina. Likewise, the development and use of effective biological and cultural control tactics requires a level of understanding of the pest and its environment that is often not available.Growers often have few choices when selecting an insecticide for use in a vegetable crop. Laws regulating pesticide registration enacted as part of the Food Quality and Protection Act of 1996 have resulted in the cancellation of many insecticide uses. Limited choices can lead to over reliance on a single insecticide chemistry hastening the development of resistance and increasing the risk of environmental impact. This research project is primarily focused on addressing applied insect pest management problems and is directed at providing science-based information to enhance the effectiveness of the North Carolina State University vegetable extension program. Research will be directed towards improving our understanding of the biology and ecology of insect pests of vegetables and improving insect management approaches in vegetable crops.

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APPROACH: <BR>Objective 1. Research efforts directed at improving pest management systems in vegetable crops will be developed and refined as needs arise throughout the duration of this project. This research will be conducted on University Research Stations and on commercial farms and will focus on the biology and ecology of pest and beneficial species at the ecosystem level. Research priorities will be ranked on the basis of industry needs and practical feasibility. Objective 1a. The needs of the vegetable industry will be evaluated through interaction with growers, consultants, cooperative extension personnel, and other university researchers. Production systems with inadequate insect sampling/scouting procedures will be identified. Collaboration with researchers in other disciplines will be sought when appropriate. Objective 1b. Areas of research will be identified as in objective 1a. Economic thresholds are the cornerstone of pest management decision making. Insect damage and its resulting impact on yield and quality of harvested produce will be determined. Proposed thresholds will be validated in on-farm tests. Objective 1c. Improvements in technology and our understanding of biology will bring with them new approaches to pest management. The application of new cultural and biological control tactics will be examined to determine their usefulness in North Carolina vegetable production systems. In addition, the compatibility of new pest management strategies with existing biological, cultural, and chemical controls will be explored. Objective 1b. Insecticide resistance bioassays will be conducted according to standard protocols for the species and chemical tested. When protocols do not exist, appropriate modifications of existing methods will be made. Collections of pest populations will be made in the field and studies will be conducted in the lab. Appropriate studies needed to evaluate potential insecticide resistance management strategies will be developed. <BR><BR>Objective 2. Research on sweetpotato will be conducted on commercial farms and in replicated small plot trails on University Research Stations. Experiments will evaluate the efficacy of currently available insecticides against root feeding pests. Research will focus on improving our understanding of the biology and ecology of the white grub, Plectris aliena, with emphasis on developing management strategies. Effects of soil type, crop rotations, soil moisture, and soil temperature will be studied at on-farm sites in Columbus County, NC. Insecticide bioassays and temperature threshold studies will be conducted at NCSU Department of Entomology lab facilities in Raleigh, NC. Additional studies will be aimed at developing economic thresholds for foliar feeding insects in sweetpotato. Plants will be mechanically defoliated at low, medium, and high rates three times during the growing season. Natural defoliation by insects will be prevented by over-spraying plots with insecticide as needed. Yield and quality of harvested roots will be measured.