Resistance of Solanum berthaultii foliage to potato tuberworm (Lepidoptera: Gelechiidae).
Ovipositional behaviour, larval establishment, and developmental biology of the potato tuberworm, Phthorimaea operculella, were compared on the foliage of 2 accessions of a wild, insect resistant potato species, Solanum berthaultii, and on a popular processing potato cultivar, Atlantic (S. tuberosum). Total egg deposition (on and off foliage) on S. berthaultii was ∼50% that on Atlantic in both free-choice and no-choice assays. In no-choice tests, only 11% of all eggs were oviposited on foliage of S. berthaultii compared 92% 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 large proportion of larvae placed on Atlantic dispersed to the abaxial leaf surface and constructed a protective silk tent before initiating feeding. Only 1 neonate placed on S. berthaultii constructed a silk tent, and no neonates dispersed to the abaxial leaf surface. The mortality of larvae confined to the foliage of S. berthaultii (accession Ber 331) was ∼7 times greater than that of larvae on Atlantic. Leaf area consumption by individual larvae was ∼50% less on the wild species compared with cultivated potato. Larvae reared on S. berthaultii produced pupae which weighed significantly less than their siblings reared on Atlantic. Collectively, these negative impacts on potato tuberworm suggest that foliage of S. berthaultii expresses characteristics, that if under genetic regulation, might be useful in creating potato tuberworm-resistant potato cultivars through traditional breeding or molecular approaches.