~ 36 ~ International Journal of Fauna and Biological Studies 2015; 2(6): 36-37 ISSN 2347-2677 IJFBS 2015; 2(6): 36-37 Received: 20-09-2015 Accepted: 22-10-2015 Elanchezhyan K Assistant Professor (Agricultural Entomology), Agricultural College and Research Institute, TNAU, Killikulam, Vallanadu, Thoothukudi District, Tamil Nadu - 628 252, India. Arumugachamy S 2 Professor and Head, Rice Research Station, TNAU, Ambasamudram, Tirunelveli, Tamil Nadu - 627 401, India. Correspondence: Elanchezhyan K Assistant Professor (Agricultural Entomology), Agricultural College and Research Institute, TNAU, Killikulam, Vallanadu, Thoothukudi District, Tamil Nadu - 628 252, India. Evaluation of medium duration rice genotypes against leaffolder, cnaphalocrocis medinalis Guen. (Pyraustidae: Lepidoptera) Elanchezhyan K, Arumugachamy S Abstract A total of 15 medium duration rice genotypes with four check entries were screened against rice leaffolder, Cnaphalocrocis medinalis (Guenee) at Rice Research Station (TNAU), Ambasamudram during Pishanam season, 2013-14. Genotypes were evaluated based on the standard evaluation system for rice with a scale of 0 - 9. The leaffolder infestation varied from 3.76 to 52.13 % of leaf damage in rice. The genotype AS 12079 recorded resistant reaction by recording less than 10% leaf damage (3.76%) with a grade 1. Nine genotypes viz., AS 12005, AS 12010, AS 12029, AS 12035, AS 12039, AS 12050, AS 12066, AS 12073 and ASRH 12001 reacted moderately resistant (11 - 20% leaf damage) to leaffolder with a grade of 3. Three rice genotypes viz., AS 12033, AS 12071, AS 12104 were moderately susceptible reaction by recording less than 35% leaf damage (Grade 5) and one genotype AS 12051 expressed susceptible reaction by recording a leaf damage of 36.24% with a grade 7. The highly susceptible genotype AS 12008 recorded the maximum infestation of 52.13 per cent leaf damage (Grade 9). None of the genotypes were free from leaf damage to be categorized as highly resistant (0% leaf damage). Keywords: Genotypes, Leaffolder, Resistance, Rice 1. Introduction Rice (Oryza sativa L.) is the most important and staple food crop for more than two thirds of the population in India. One of the major yield limiting factor in rice cultivation is the attack of insect pests that causes 20-30 per cent losses every year [6] . Rice is affected by number of insect pests during its different growth stages. Among the various insect pests damaging the rice crop, the leaffolder, Cnaphalocrocis medinalis Guen. (Pyraustidae: Lepidoptera) is one of the regular pests of rice. It causes heavy losses at the early vegetative stage, medium at tillering stage and low at the milky stage [4] . It has been recorded to cause 63 to 80 per cent yield loss in rice [3, 5] . The leaffolder damages the crop in its larval stage. The young larvae feed on open leaves but later feed inside the rolled leaf formed by folding the leaf longitudinally with a sticky substance. The scraped leaves become membranous, turn whitish in colour. A single larva can damage a number of leaves. This activity disturbs the photosynthesis and plant growth and ultimately yield is reduced. Farmers depend upon a great deal of insecticide applications, even though a lot of insecticide applications are not effective [7] . Therefore, the challenge before the agricultural scientists today is to produce insect resistant plants. Insect resistant plants have the ability to withstand the effects of an insect by becoming resistant to its ill effects by means of genetic manipulation [8] . Growing resistant varieties is an important component of rice IPM as it is compatible with all the methods of pest control without producing any side effects to the environment. Hence, the present study aimed to identify the new sources of resistant genotypes developed at Rice Research Station (TNAU), Ambasamudram for the management of leaffolder for the benefit of farming communities. 2. Materials and Methods A total of 15 medium duration rice genotypes and four check entries were collected from Plant Breeding Section, Rice Research Station, Ambasamudram for screening against leaffolder, C. medinalis in rice under field condition during Pishanam season, 2013-14. The crop was raised adopting standard agronomic practices of irrigation and fertilizer except plant protection measures. The damaged and undamaged leaves were recorded at the time of peak infestation.