Resistance to the potato tuber moth, Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae), in potato (Solanum tuberosum ssp. tuberosum L.) tubers

Tests were undertaken with tubers of four potato cultivars to determine whether differences were apparent in susceptibility to the insect pest the potato tuber moth (Phthorimaea operculella). Under choice test conditions, in which neonates were allowed to invade intact potato tubers, there was no significant difference in the numbers of larval mines established within the tubers of four potato cultivars. However, significantly more mines were initiated in the vicinity of tuber eyes than elsewhere for all cultivars. Under non-choice test conditions, in which neonates were placed on the surface of intact tubers, resistance was indicated by significantly fewer larvae surviving to eclose as adults on tubers of cultivar Sequoia than on cultivars Kennebec and Tarago. Cultivar Netted Gem yielded an intermediate number of adults. In a third experiment using cultivar Kennebec alone, survival of neonates to adults was significantly increased by pricking the tuber surface immediately prior to inoculation, indicating that the tuber periderm may constitute a significant barrier to invasion. Results are discussed in relation to possible resistance mechanisms and further work required for developing host plant resistance against this pest.