Abstract

Non-preference and antibiosis components of resistance to the leat hopper. Amra- sca biguttula biguttula Ishida were studied in cotton H8 69 (Resistant). GS 23 (lolerant) in relation to the susceptible variety PRS 72. The results indicated the discriminating behaviour of leat hopper for the cotton varieties for feeding. The variety PRS 72 harboured as high as 30,96 nymphs/plant showing its greater susceptibility while GS 23 and HB 69 were less preferred with 18.88 and 10.32 nymphs/plant respectively indicating their relative resistance. The susceptible PRS 72 and tolerant GS 23 were more preferred for oviposi tion by recording a population of 27.04 and 17.88 nymphs per plant respectively as against only 10.68 in the case of resistant HB 69. The lower lamina of resistant HB 69 had a high density of hairs (97.80/Sq.cm) than the susceptible PRS 72 (8.11/Sq.cm). Resistant HB 69 showed less fecundity per leaf hopper (9.9 nymphs), long nymphal period (16.48 days) and less percentage of nymphs becoming adults (19.9%) compared to high fecundity (30.2 nymphs) high percentage of nymphs becoming adults (64.1%) and short nymphal period (9.36 days) in the susceptible PRS 72.

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