Characterization of Wild Rice Species in Response to Leaffolder Cnaphalocrocis Medinalis

The rice leaffolder, Cnaphalocrocis medinalis (Gn) attained the status of major pest during the last few years in major rice growing areas of the world. To search for possible sources of resistance against leaffolder, an experiment comprising 14 species of wild rice (Oryza sp.), three extensively cultivated varieties of rice in Pakistan together with one susceptible check of cultivated rice was conducted in the greenhouse of National Agricultural Research Centre, Islamabad during 2005. Most of the tested wild species and the three cultivated varieties showed susceptibility to leaffolder. O. australiensis was highly susceptible to leaffolder with maximum damage rating score of 9 and highest percent infestation of 56.6. O. alta, O. barthii, O. grandiglumis, O. glumaepatula, O. latifolia, O. longistaminata, O. nivara, O. officinalis, O. punctata and O. rhizomatis gave damage rating score of 5 and were moderately susceptible to leaffolder. However, two wild species, O. brachyantha and O. rufipogon were found resistant to leaffolder with damage rating scale of 1. O. brachyantha and O. rufipogon showed low percent infestation values of 3.7 and 5.26, respectively. Whereas, O. meridionalis expressed moderate level of resistance with damage rating score of 3. Of the cultivated varieties used in the present study, Bas-385 and KSK-282 were found susceptible to this pest, with damage rating score of 7 while IR-6 was moderately susceptible with damage rating scale of 5. The use of these resistant wild species via hybridization program i s, t herefore, s uggested t o i ncorporate r esistance genes t o c ultivated r ice and t o d evelop r ice c ultivars resistant to this major insect pest