2011 Annual Report
1a.Objectives (from AD-416)
1. Identify and characterize host plant resistance and facilitate incorporation of resistance factors into advanced breeding lines of watermelon (for sweetpotato whitefly) and sweetpotato (for the complex of soil-borne insects including but not limited to wireworms, flea beetles, cucumber beetles, white grubs, and sweetpotato weevils): 1.A Characterize watermelon germplasm lines with resistance to the sweetpotato whitefly and incorporate resistance factors into advanced watermelon breeding lines; 1.B. Identify and characterize sweetpotato clones with resistance to soil insect pests and use a recurrent mass selection breeding approach to generate clones with high levels of resistance and good horticultural characteristics.
2. Assess the importance and utility of biological control agents for the management of insect pests of cucurbits to include sweetpotato whitefly using predators and parasitoids, and for pickleworms using nucleopolyhedroviruses (NPV). 2.A. Develop NPVs for management of pickleworms and other pests of cucurbits; 2.B. Assess the effect of mixed plantings of cucurbits with other vegetables and plant species on the population abundance and behavior of predators and parasitoids for the management of the sweetpotato whitefly.
3. Identify whitefly-host plant-virus relationships and develop methods for protection from the whitefly-vectored viruses of vegetables such as sweetpotato and watermelon.
1b.Approach (from AD-416)
Conduct greenhouse and field trials to identify sources of resistance and evaluate genetic populations to determine heritability of resistance against sweetpotato whiteflies in melon and watermelon, and against soil insect pests of sweetpotatoes; cross appropriate germplasm to facilitate incorporation of resistance into advanced sweetpotato breeding lines and new cultivars; evaluate chemical and physical mechanisms of resistance in sweetpotato to soil insect pests; investigate the influence of resource plants on predators and parasitoids of whiteflies in cage and field trials; assess the usefulness of baculoviruses for control of pickleworms and other cucurbit pests; study the epidemiology of sweet potato leaf curl virus in sweetpotato; and survey the presence and epidemiology of whitefly-transmitted viruses of cucurbits.
As part of the on-going sweetpotato breeding program at the U.S. Vegetable Laboratory (USVL) in April 2011, 1931 first-year sweetpotato seedlings (from true seed) were transferred directly to the field as single-plant plots, which will be harvested and analyzed in August 2011. Also in 2011, 460 established sweetpotato clones were planted in replicated field plots at the USVL. Roots from these plots will be harvested in October 2011. Three breeding blocks (seed nurseries) were planted in 2011, and seed collection will begin in October 2011. Two groups of 20 and 32 sweetpotato clones were challenged with root knot nematodes and evaluated for disease resistance in a greenhouse experiment. Studies on transmission of Sweet Potato Leaf Curl Virus (SPLCV) by the sweetpotato whitefly highlighted the increasing importance of this virus for sweetpotato growers. An experiment was setup in the field in July 2011 at the USVL to investigate the epidemiology of this disease as it spreads through sweetpotato plots.
This project is the replacement for project 6659-22000-022-00D, NEW APPROACHES FOR INSECT PEST MANAGEMENT IN VEGETABLE CROPS.
Simmons, A.M., Abd-Rabou, S. 2011. Populations of predators and parasitoids of Bemisia tabaci (Hemiptera: Aleyrodidae) after the application of eight biorational insecticides in vegetable crops. Pest Management Science. 67:1023-1028. DOI: 10.1002/ps.2155.