Resistance of Solanum berthaultii Foliage to potato tuberworm (Lepidoptera: Gelechiidae)

Ovipositional behavior, larval establishment, and developmental biology of the potato tuberworm, Phthorimaea operculella Zeller, were compared on foli age of 2 accessions of a wild, insect-resistant potato species, Solanum ber thaultii Hawkes, and that of a popular processing potato cultivar, Atlantic (S. tuberosum L.). Total egg deposition (on and off foliage) on S. berthau ltii was (approximate to 1/2 that on Atlantic in both free-choice and no-ch oice assays. In no-choice tests, only 11% of all eggs laid were deposited o n foliage of S. berthaultii compared with a 92% deposition rate on foliage of Atlantic, suggesting the presence of a chemical or physical deterrent or the absence of ovipositional stimulants on foliage of S. berthaultii. A la rge proportion of larvae placed on Atlantic dispersed to the abaxial leaf s urface and constructed a protective silk tent before initiating feeding. On ly 1 neonate placed on S. berthaultii constructed a silk lent, and no neona tes dispersed to the abaxial leaf surface. Mortality of larvae confined to the foliage of S. berthaultii (accession Ber 331) was (approximate to 57 ti mes greater than that of larvae on Atlantic. Leaf area consumption by indiv idual larvae was approximate to 50% less on the wild species compared with cultivated potato. Larvae reared on S. berthaultii produced pupae which wei ghed significantly less than their siblings reared on Atlantic. Collectivel y, these negative impacts on potato tuberworm suggest that foliage of S. be rthaultii expresses characteristics. that if under genetic regulation, migh t be useful in creating potato tuberworm-resistant potato cultivars through traditional breeding or molecular approaches.