Location: Vegetable Research
Title: Insect Interactions in Sweetpotato Breeding Nurseries Author
Submitted to: Journal of Agricultural and Urban Entomology
Publication Type: Abstract Only
Publication Acceptance Date: September 27, 2010
Publication Date: September 9, 2011
Citation: Jackson, D.M. 2011. Insect Interactions in Sweetpotato Breeding Nurseries. Journal of Agricultural and Urban Entomology. 26:132-133. Technical Abstract: Sweetpotato, Ipomoea batatas (L.) Lam. (Convolvulaceae), is a vital staple food crop in much of the developing world, and it is an important specialty crop in the United States. American consumers prefer sweetpotatoes with sweet, moist orange flesh. After many years of decline beginning in the 1950s, per capita consumption of sweetpotatoes has shown a modest increase over the past 10 years. This increase has much to do with increased awareness of American consumers to the health benefits associated with consuming this nutritious vegetable. Worldwide sweetpotato production has also increased due to interest in this crop as food, biofuel, animal feed, or source of starch or neutraceutical products, such as the antioxidants ß-carotene and anthocyanins. Unfortunately, many insect pests damage sweetpotato roots in the field, and for over forty years there has been an active breeding program at the U.S. Vegetable Laboratory (USVL) to develop pest-resistant sweetpotato cultivars. This program has made significant progress in increasing insect resistance in sweetpotato germplasm with high quality, good yield, and superior disease resistance. Sweetpotato is a hexaploid and most quality characteristics are inherited qualitatively, which makes breeding efforts difficult. Also, the crop is clonally propogated from year to year using sprouted roots or greenhouse cutting, so once a variety is released, it cannot be improved any further. For breeding sweetpotatoes at the USVL, we us a recurrent mass selection methodology based on quantitative genetic principles. Key to this method is the polycross breeding nursery where up to 25 parents are randomly distributed within four replicated blocks in an isolated field. These polycross nurseries depend on natural pollination by bees and other insects. Unpollinated flowers dehise and do not produce seeds, thus it is important to protect natural bee populations in ensure maximum seed production. There are several other insect species that frequent sweetpotato seed nurseries that are quite destructive. Foliar feeders, such as armyworms, tortoise beetles, and the sweetpotato hornworm can cause significant damage to sweetpotato plants, but they are easily controlled. Of much more concern at the USVL is the potato leafhopper, Empoasca fabae (Harris) (Homoptera: Cicadellidae). These insects reach high numbers, and if not controlled they can severely stunt or kill the sweetpotato plants in a polycross nursery. They are also difficult to manage because most of the insecticides used to control them are also toxic to bees. Sprays of materials with a short residual activity should be applied in the afternoon after the sweetpotato flowers close and fewer bees are present.