Screening of Iranian Potato Germplasm for Resistance to the Potato Tuberworm Phthorimaea operculella (Lepidoptera: Gelechiidae)

Abstract

The potato tuberworm, Phthorimaea operculella (Zeller), is an important insect pest of potato, Solanum tuberosum L., both in storage and in the field. In this research, tubers of eight commercial potato cultivars and four Iranian selections with equal weight and dormancy were exposed to 10 pairs of adult P. operculella in a climate chamber set at 25 ± 1 °C, 65 ± 5 % RH and total darkness. In a free-choice situation, oviposition was lower on 397082–2, Khavaran and Morene compared to the other germplasm that were exposed to adults of P. operculella. Number of mines per tuber, length of mines per tuber, time of development of larvae, number of pre-pupae produced per tuber, weight of pre-pupae and number of eggs developed in ovaries per female were counted and/or measured on each commercial cultivar and selection. There were fewer and shorter mines on tubers of 397082–2, Khavaran and Morene compared to the other potato germplasm. The number of pre-pupae produced per tuber and the weight of pre-pupae were lower when P. operculella was reared on tubers of 397082–2, Khavaran and Morene. Also the development, survival and fecundity were lower when P. operculella was reared on those same germplasm. Flesh firmness was negatively correlated with larval survival (r 2 = 0.87); in addition, the percentage of starch and macronutrient composition was low on these three germplasm. Thus, tuber flesh firmness of these germplasm could delay larval penetration and lower establishment 397082–2, Khavaran and Morene showed promising traits that can be integral component of potato breeding for resistance to P. operculella and pest management programs.