Mechanisms of resistance to the brown planthopperNilaparvata lugens in wild rice (Oryza spp.) cultivars

Three wild rice species and six cultivated rice varieties were evaluated to determine their mechanisms of resistance toNilaparvata lugens (Stal.). Wild rice species,Oryza officinalis, O. punctata, andO. latifolia and cultivated rices Rathu Heenati (Bph 3), Babawee (bph 4), ARC 10 550 (bph 5), Swarnalata (Bph 6), Ptb 33 (bph 2+Bph 3) and the susceptible Taichung Native (TN 1) (no resistance gene) were included in the study. In a free choice seedbox screening test, wild rice species maintained their high level of resistance through the 48 h exposure toN. lugens nymphs while plant damage ratings of cultivated rice varieties increased with time. Wild rices were non preferred and significantly more individuals settled on susceptible TN 1 followed by cultivated rices. The quantity of food ingested and assimilated byN. lugens on wild rices was less than on cultivated resistant varieties.N. lugens caged on resistant wild rices had slow nymphal development, reduced longevity, low fecundity, and low egg hatchability as compared toN. lugens on cultivated resistant varieties.