ARS | Publication request: Insect resistance in traditional and heirloom sweetpotato varieties

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 11, 2013
Publication Date: N/A

Interpretive Summary: For any vegetable breeding program, the discovery of new genetic sources of desirable characteristics is essential for the improvement of that crop. Commercial sweetpotato cultivars have little resistance to soil insect pests, which can severely limit marketable yields. Thus, there is a need to develop new varieties that have increased levels of insect resistance. ARS scientists at Charleston, SC, evaluated 59 sweetpotato clones, including insect-susceptible and insect-resistant check cultivars for resistance in replicated field trials. Among the clones evaluated were traditional and heirloom sweetpotato cultivars that were obtained from the USDA, ARS, sweetpotato germplasm collection in Griffin, GA, and other sources. Several of the traditional and heirloom cultivars were more resistant to soil insect pests than were the susceptible check varieties. The most promising of these materials could be used as parental materials in a sweetpotato breeding program focused on improving pest resistance while maintaining yield and quality.

Technical Abstract: Fifty-nine sweetpotato cultivars, including several heirloom and traditional varieties, were evaluated for resistance to soil insects in field experiments during 2010-2011 at the USDA, ARS, U. S. Vegetable Laboratory (USVL), Charleston, SC. These experiments included two insect-susceptible control cultivars (‘Beauregard’ and ‘SC1149-19’) and four insect-resistant control cultivars (‘Charleston Scarlet’,‘Regal’, ‘Ruddy’, and ‘Sumor’) developed by the USDA, ARS, USVL, sweetpotato breeding program. These cultivars differed significantly in resistance measured by the percentage of uninjured roots, WDS (Wireworm, Diabrotica, and Systena) index, the percentage of roots damaged by the sweetpotato weevil (Cylas formicarius [Fabricius]), the percentage of roots damaged by the sweetpotato flea beetle (Chaetocnema confinis Crotch), and the percentage of roots damaged by white grub larvae (including Plectris aliena Chapin and Phyllophaga spp.). Forty-one sweetpotato cultivars had a lower percentage of uninjured roots than the susceptible control genotype,‘SC1149-19’, while 33 varieties had a lower percentage of uninjured roots than ‘Beauregard’, one of the leading commercial orange-fleshed cultivars in the United States. ‘SC1149-19’ also had a higher WDS index, and higher percentages of infestation by flea beetles, white grubs, and sweetpotato weevils than most other sweetpotato genotypes in this study. The moderate to high levels of resistance to soil insect pests exhibited by many of these traditional and heirloom cultivars may provide useful sources of germplasm for sweetpotato breeding programs.