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United States Department of Agriculture

Agricultural Research Service

2007 Annual Report

1a.Objectives (from AD-416)
Specific objectives are to a) Identify and characterize host plant resistance to sweetpotato whitefly in melons and to the soil insect complex in sweetpotato, and facilitate incorporation of resistance factors into advanced breeding lines and new vegetable cultivars; b) assess the importance of biological control agents of sweetpotato whitefly and of insect pests of sweetpotato and cucurbits, and develop techniques for their conservation and utilization as management tools in vegetable production systems; and c) develop cost effective, biologically-based technologies for use in integrated pest management (IPM) programs for sweetpotato, cucurbits, and other vegetable crops.

1b.Approach (from AD-416)
Identify sources of resistance and determine heritability of resistance against sweetpotato whiteflies in melon and watermelon, and against soil insect pests of sweetpotatoes; facilitate incorporation of resistance into advanced sweetpotato breeding lines and new cultivars; determine chemical and physical mechanisms of resistance in sweetpotato to soil insect pests; investigate the influence of leguminous host plants on parasitoids of whiteflies; survey predators in South Carolina for biological control agents for whiteflies; determine overwintering ability of whitefly predator Delphastus catalinae; establish food preferences of predator Engytatus modestus; assess the use of baculoviruses for control of pickleworms, melonworms, and soil pests of sweetpotatoes; develop trapping methods for pickleworm moths, melonworm moths, sweetpotato weevils, Diabrotica spp., and whiteflies using pheromones and kairomones; evaluate alternative cropping systems for sweetpotatoes and other vegetables; and evaluate LED-modified traps for whitefly control.

3.Progress Report
As part of the on-going sweetpotato breeding program at the US Vegetable Laboratory (USVL), several hundred sweetpotato clones were evaluated for damage by soil insect pests. In that process, several first-year seedlings, second-year seedlings, intermediate clones, and advanced clones were identified as being resistant to insect pests. These clones were also evaluated for yield, quality, and disease resistance. A reduced tillage system for growing sweetpotatoes in a killed cover crop was evaluated for the third year. Yield and quality of sweetpotatoes in this system were similar to those grown in a conventional tillage system. The impact of humidity on a beneficial predator of whiteflies, Delphastus catalinae, was investigated under controlled laboratory conditions. The performance (egg laying, hatching, survival, and body size) of this predator was detailed over a range of humidities. Low humidity was found to have the most adverse effect on the biology of the beetle. The results help define conditions in which this beetle can be most effective against whiteflies. Several baculoviruses were bioassayed against pickleworm larvae. Velvet bean caterpillar NPV was very effective in killing pickleworm larvae, however, 7 other NPVs were relatively ineffective against this pest. New trap designs were evaluated in the field for squash vine borer and sweetpotato weevils.


5.Significant Activities that Support Special Target Populations

6.Technology Transfer

Number of non-peer reviewed presentations and proceedings18
Number of newspaper articles and other presentations for non-science audiences1

Review Publications
Jackson, D.M., Bohac, J. 2006. Improved Dry-fleshed Sweetpotato Genotypes Resistant to Insect Pests. Journal of Economic Entomology 99:1877-1883.

Simmons, A.M., Legaspi, J.C. 2007. Ability of Delphastus Catalinae (Coleoptera: Coccinellidae), a Predator of Whiteflies (Homoptera: Aleyrodidae), to Survive Mild Winters. Journal of Entomological Science. 42:163-173.

Jackson, D.M., Bohac, J. 2006. Survival and Growth of Diabrotica Balteata Larvae on Insect-Resistant Sweetpotato Genotypes. Journal of Agricultural and Urban Entomology. 23:77-86.

Canhilal, R., Carner, G.R., Griffin, R.P., Jackson, D.M., Alverson, D.R. 2006. A Life History of the Squash Vine Borer, Melittia Cucurbitae (harris) (lepidoptera: sesiidae) in South Carolina. Journal of Agricultural and Urban Entomology. 23:1-6.

Jackson, D.M., Bohac, J. 2007. Resistance of Sweetpotato Genotypes to Adult Diabrotica Beetles. Journal of Economic Entomology. 100:566-572.

Last Modified: 7/4/2015
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