My research focuses on the ecology and management of insect pests of commercial vegetable crops in North Carolina. Major emphasis is placed on providing science-based information to address problems in insect pest management and enhance the effectiveness of the vegetable extension program at NC State University. Primary interests are in developing/refining economic thresholds, managing insecticide resistance, and improving sampling procedures in agronomic systems.

Current Research Projects:

Ecology and Management of the exotic white grub Plectris aliena

Plectris aliena is an invasive white grub that was introduced into the United States at Charleston, SC from South America around 1900. Since 2006, P. aliena has been a consistent and pernicious pest of sweetpotato in the southeastern production region of North Carolina. Growers estimate that the insect has affected over 90% of the sweetpotato acreage in the Columbus County, NC area since 2006 resulting in significant lost revenue. The immature or grub stage of the insect lives below ground and feeds voraciously on sweetpotato storage roots. The current dearth of knowledge about the insect’s biology severely limits opportunities for developing integrated pest management tactics. Our research addresses key management challenges by filling in the gaps that currently exist in the knowledge of Plectris aliena’s biology and developing management tools that exploit this knowledge. The research is supported in part by the North Carolina Sweetpotato Commission, the North Carolina Agricultural Foundation, and the USDA Southern Region IPM Program.

Identifying risk factors associated with wireworm damage in Irish potato

Wireworms have become an increasingly serious concern for potato growers in North Carolina in recent years. Wireworm larvae live below the soil surface and feed on the roots and stems of growing plants. The insects are capable of damaging potatoes by feeding on the seed piece shortly after planting, but direct feeding on the developing tubers presents the greatest risk to the crop. There is currently no effective control strategy that specifically targets wireworms feeding on developing tubers. Wireworm damage on table-stock potatoes can be devastating because of low thresholds for external defects. Published reports indicate that in some years as much as 45% of the potato crop can be downgraded in quality because of wireworm damage. Of significant concern is the fact that there is currently no method for growers to ascertain which fields are likely to harbor populations of wireworms. Cultural practices and environmental conditions have been shown to have a significant impact on wireworm abundance and crop damage in numerous studies across the US. Nevertheless, the importance of these factors in determining risk of wireworm damage in potato in North Carolina is unknown. For this reason nearly all potato fields in North Carolina are treated preventatively with insecticide for wireworms whether they need it or not.

Our research will identify the species of wireworm present in North Carolina potato production systems. Studies also focus on identifying cultural practices and environmental conditions that influence the risk of wireworm damage to potato. The ultimate goal of this project is to develop a wireworm risk assessment tool for potato that will enable informed and effective pest management decisions.   Funding for this research is provided by the USDA/NCDA Specialty Crops Block Grant.

Other projects:

• My lab is currently working as a part of a multidisciplinary team funded by the USDA Specialty Crop Research Initiative to evaluate factors that influence storage root initiation in sweetpotato. We are specifically studying the effect(s) of soil applied insecticides on the timing of storage root initiation.
• Wireworms are the most important economic pest of sweetpotato in North Carolina, and my lab conducts research in the area of wireworm biology and management. Recent studies identified the most damaging wireworm species in sweetpotato, and our current management strategies are based on the biology of the most abundant species. Currently, our research focuses on identifying new, reduced risk options for controlling wireworms in sweetpotato including insecticides, and biological control organisms.
• Tomato spotted wilt is an insect vectored viral disease of fruiting vegetables in the Southern US. The disease has the potential to cause severe economic losses in years of high virus/vector incidence. My lab is currently involved in a multistate, multidisciplinary research and extension project funded by USDA’s Risk Avoidance and Mitigation Program with the goal of developing improved tactics for managing the disease and the thrips that vector it. Cultural and chemical controls and host plant resistance are being evaluated.