Development of Test Methods and Screening for Resistance to Thrips in Capsicum Species

Abstract

Thrips are one of the most damaging pest organisms in field and greenhouse pepper (Capsicum) cultivation. They can cause damage on pepper directly by feeding on leaves, fruits and flowers, and indirectly by transferring viruses, especially Tomato Spotted Wilt Virus (TSWV). No commercial pepper varieties are available with an effective level of resistance to thrips. Our research is aimed at the development of tools for breeding varieties with a broad resistance to thrips. This encompasses setting up of effective test methods, the identification of sources of resistance and mapping of QTLs for resistance. Thirty-two pepper accessions of four species of pepper (Capsicum annuum, C. baccatum, C. chinense and C. frutescens) originating from different geographic and climatic regions were tested for resistance using several screening methods. The tests were performed in Indonesia and the Netherlands with Thrips parvispinus and Frankliniella occidentalis, respectively. Accessions were tested under choice (screenhouse, greenhouse) and non-choice (leaf disc, detached leaf and cuttings) conditions. Screening methods were compared and correlations among these methods were assessed. We observed a large variation for resistance to thrips in pepper. Our results also indicate that the leaf disc test can be used as an efficient and predictive screening method for thrips resistance in pepper. An F2 population from a cross between a highly resistant and a susceptible accession was produced and currently we are studying the inheritance of resistance in this population.