Suitability of graminaceous weed species as host plants for rice leaffolders, Cnaphalocrocis medinalis and Marasmia patnalis.
The suitability of 12 graminaceous weeds of rice fields as host plants for 2 rice leaffolders, Cnaphalocrocis medinalis and Marasmia patnalis, was compared with a susceptible (IR 36) and a moderately resistant (TKM 6) rice variety in laboratory and greenhouse tests. Although rice was the most preferred host of the 2 leaffolder species, their responses to the test weeds varied significantly. Cnaphalocrocis medinalis responded better to most of the test weeds than did M. patnalis, suggesting a wider host range for C. medinalis. Third instar larval orientation and settling, and food consumption and assimilation of C. medinalis on Leersia hexandra, Echinochloa frumentacea (syn. Echinochloa crus-galli), Echinochloa glabrescens, Echinochloa colona, and Leptochloa chinensis were comparable with those on susceptible IR 36 and moderately resistant TKM 6 rice varieties. First instar larval settling of C. medinalis on L. hexandra was similar to that on IR 36. The growth of C. medinalis on Eleusine indica was comparable with that on IR 36. Oviposition by C. medinalis on IR 36, TKM 6, E. indica and L. chinensis was high and similar. The performance of M. patnalis on L. hexandra was better than on other test weeds but not similar to IR 36 or TKM 6 varieties in all the behavioural and physiological criteria used. Authors' summary. KEYWORDS: TROPAG | Oryza sativa | Leersia hexandra | Echinochloa | Leptochloa chinensis | Eleusine indica | pest insects | Cnaphalocrocis medinalis | Marasmia patnalis | hosts | weeds | Oryza.