ORIGINAL CONTRIBUTION Tuber production, dormancy and resistance against Phthorimaea operculella (Zeller) in wild potato species F. G. Horgan 1 *, D. T. Quiring 1 , A. Lagnaoui 2† & Y. Pelletier 1,3 1 Population Ecology Group, Department of Biology, University of New Brunswick, Fredericton, NB, Canada 2 Departamento de Entomolog  ıa y Nematolog  ıa, Centro Internacional de la Papa, Lima, Peru 3 Potato Research Centre, Agriculture and Agri-Food Canada, Fredericton, NB, Canada Keywords Gelechiidae, host–plant resistance, periderm, Peru, potato breeding, potato tuber moth Correspondence Finbarr G. Horgan (corresponding author), International Rice Research Institute, DAPO Box 7777, Metro Manila, The Philippines. E-mail: f.horgan@irri.org *Present address: International Rice Research Institute, DAPO Box 7777, Metro Manila, The Philippines. †Present address: Division of Environmentally and Socially Sustainable Development, The World Bank, Washington, DC, USA. Received: November 4, 2012; accepted: March 13, 2013. doi: 10.1111/jen.12055 Abstract The diversification of resistant potato varieties at a landscape level could slow adaptation by Phthorimaea operculella to potato resistance and pro- mote sustainable crop protection. In this study, we assessed wild potato species as novel sources of foliage and tuber resistance against P. operculel- la. Tuber resistance was quantified for 136 and foliage resistance for 54 potato accessions representing 14 and nine potato species, respectively. Several accessions were highly resistant to moth damage in tubers and/or foliage. In particular, Solanum chiquidenum and Solanum sandemanii were highly resistant to damage in tubers. Several accessions of Solanum multiin- terruptum and a small number of accessions of Solanum bukasovii, Solanum berthaultii, Solanum sparsipilum and Solanum wittmackii also had highly resistant tubers. Larval survival on foliage of S. bukasovii and S. chiquide- num was generally low. New resistance sources are listed, and insect per- formance on the plants is described with possible resistance mechanisms. The study also examined potential trade-offs associated with resistance. Tuber resistance was negatively correlated with the number and weight of tubers produced per plant, but positively correlated with the length of dor- mancy across accessions, indicating that, although long dormancy is not a prerequisite for resistance, species and accessions with extended dor- mancy will have more resistant tubers. Tuber and foliage resistance were generally positively correlated across all accessions; however, among accessions from within a potato species, there were negative (S. berthaul- tii), positive (S. chiquidenum) and non-significant (S. bukasovii) relations. These results indicate that, besides identifying novel resistance sources, an improved understanding of the mechanisms and inherent trade-offs asso- ciated with tuber and foliage resistance will improve the efficiency of potato breeding programmes aimed at enhancing resistance against P. operculella. Introduction The potato tuber moth, Phthorimaea operculella (Zeller), is one of the most damaging insect pests of crop potato (Solanum tuberosum Grp Tuberosum) worldwide (Rondon 2010; Pelletier et al. 2013). The tuber moth causes serious losses to potato production by damaging foliage and tubers in the field and tubers in storage (Rondon 2010). Moth infestations of tubers in rustic storage facilities, particularly in tropical and subtropical regions, can sometimes cause the com- plete loss of farmers’ potato stocks. Even when moth damage is not severe, bacteria and fungi will some- times infect potato tubers through wounds created by the moths, causing a reduction or loss of market value (Rondon 2010). Commercial and edible native pota- J. Appl. Entomol. 137 (2013) 739–750 © 2013 Blackwell Verlag GmbH 739 J. Appl. Entomol.