Identification of rice leaf folder species (Lepidoptera: Pyralidae) and the damage on paddy at Rantau Panjang paddy field, Kelantan

Rice leaf folder is one of the pests in most growing area of paddy. Three species of rice leaf folder were identified at Rantau Panjang paddy field, Kelantan. The species were Cnaphalocrocis medinalis (Guenee), Marasmia patnalis (Bradley) and Marasmia ruralis (Walker). Among the species, M patnalis (Bradley) was the dominant species at the paddy field. The percentage of M. patnalis in study plot 1 (90.5%), 2 (89.5%) and 3 (100%) respectively, whereas the percentage of C. medinalis in plot 1 (9.5%) , plot 2 (5.3%) and plot 3 (0%) while the percentage of M. ruralis in the three plots were plot (0%), plot 2 (5.3%) and plot 3 (0%). The sex ratio varied among the species. In all species, males dominated the females. The symptoms of leaf folder damage are the longitudinal folded leaves with stitches of threadlike silk. The larvae of rice leaf folder feed by scraping the green mesophyll from within the folded leaves, resulting in linear, pale white stripe damage to the leaf. The percentage of damage leaves in three research plots at Rantau Panjang paddy field is 13.7%. The physical factors that contribute to the growing population of rice leaf folder at Rantau Panjang paddy field was the practice of mixing pesticides or "cocktail" by the farmers and the used of same mode of action of pesticides for controlling several pests at the same time which may reduce the effectiveness or functions of the pesticides. For this factors, some of the rice leaf folders has develop resistance to the same pesticides which usually have been applied for long time of rice cultivation at this paddy field and contribute to the growing population of these insect.