Resistance Profiling of IIOR Castor Parental Lines against Major Insect Pests under Natural Infestation

Fifteen parental lines of castor (Ricinus communis L.) maintained by the ICAR–Indian Institute of Oilseeds Research (IIOR) were evaluated under natural field infestation at TCRS, Yethapur, during Kharif 2015 to characterise their reaction to major insect pests. The test entries were assessed for leafhopper (Empoasca flavescens), thrips (Retithrips syriacus/Scirtothrips dorsalis), castor semilooper (Achaea janata), tobacco caterpillar (Spodoptera litura) and capsule borer (Conogethes punctiferalis). Leafhopper injury was classified using a 0–4 hopper-burn scale. DCS 110, DCS 118, DCS 123 and M 574 showed grade 0 reactions, with leafhopper populations of 6.33–9.83 per three leaves per plant. In contrast, DCS 109 and DPC 9 were grade 4, recording 69.35 and 73.32 leafhoppers per three leaves per plant, respectively. Thrips infestation ranged from 3.66 to 7.50 thrips per spike, while semilooper incidence remained low at 0.00–0.67 larvae per plant. M 571 recorded 12.17 S. litura larvae per plant, whereas most other lines had negligible or no infestation. DCS 118, DCS 123, M 571, M 574 and DCH 519 had no capsule-borer damage; DCS 110 recorded the highest damage at 9.21%. Considering the combined pest profile, DCS 118 and DCS 123 were the most promising lines for use as donor parents in breeding programmes targeting multiple-pest resistance.