Studies on Antixenosis in Castor, Ricinus communis L. Against Major Insect Pests
The morphological characters leading to antixenosis type of resistance, against Spodoptera litura (Fabr.) and capsule borer, Conogethes puncliferalis Guen were studied during 2000 and 2001. The castor genotypes with leaves of papaya type (RG-1766). flat (RG-2291), shallow cup (RG-2327) and small size leaves (RG-2679) were less preferred by Spodoptera than those with purple (RG-1930) and large size leaves (RG-11). The capsule borer infestation was low in the genotypes with loose (RG-1934) and very loose (RG-2543) spikes and with small sized (RG-2635) and non-spiny capsules (RG-258). The castor genotypes with double and triple bloom viz., RG-2551 and 2646 were less preferred by the leafhopper, Empoasca flavescens (Fabr.) and exhibited lower degree of hopper burn while the zero and single blooms were more preferred. Similar reaction of castor was found against thrips, while it was reverse in case of whitefly. The hybrid DCH-177, with single boom was susceptible to leafhopper.