Suitability of graminaceous weed species as host plants for rice leaffolders, Cnaphalocrocis medinalis and Marasmia patnalis

Abstract

The suitability of 12 graminaceous weeds of ricefields as host plants for two rice leaffolders, Cnaphalocrocis medinalis (Guenée) and Marasmia patnalis Bradley (Lepidoptera: Pyralidae) was compared to a susceptible (IR36) and a moderately resistant (TKM6) rice variety in laboratory and greenhouse tests. Although rice was the most preferred host of the two 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 crus-galli, Echinochloa glabrescens, Echinochloa colona, and Leptochloa chinensis were comparable to those on susceptible IR36 and moderately resistant TKM6 rice varieties. First instar larval settling of C. medinalis on Leersia hexandra was similar to that on IR36. C. medinalis growth on Eleusine indica and IR36 was comparable. Oviposition by C. medinalis on IR36, TKM6, Eleusine indica, and Leptochloa chinensis was high and similar. Performance of M. patnalis on Leersia hexandra was better than on other test weeds but not similar to IR36 or TKM6 varieties in all the behavioral and physiologial criteria used.