Paper Title
Evaluation of Bio-Efficacy of Abamectin 0.5 % GR Against Rice Root-Knot Nematodes (Meloidogynegraminicola) and its Suitabilityin Nematode Outbreak Management

Abstract
Rice root-knot nematodes, Meloidogynegraminicolais becoming a major threat in rice cultivation especially in Sri Lanka. Abamectin is widely used to manage M. graminicola, but it is important to check its bio-efficacy which can be recommended even in outbreak conditions. Therefore, this study was conducted to evaluate the bio-efficacy of Abamectin 0.5% GR. Before conducting bio-efficacy tests, a survey was conducted in 2022/2023 Maha season to observe the level of nematode infestation in 9 selected areas where nematode infestations were prominent. The highest percentage of nematode infestation/plantwas recorded in Mahaweli System B (44.8%) followed by Mahaweli System C (41.4%), and Kaluthara (33.0%). Then testing of the bio-efficacy of Abamectin 0.5% GR against rice root-knot nematodeswas conducted in greenhouse and field conditions. Two trials were conducted under greenhouse conditions as artificial inoculation and natural infestation. It was observed that soil treated with Abamectin 0.5% GR (50 kg/ha) had a significantly lower gall development in plants when compared to untreated control. In addition, the lowest number of live nematodes in 10 ml of extraction was shown in Abamectin 0.5 % GR treated soil samples. The field trials were conducted in Mahaweli System B, Mahaweli System C, and Kaluthara. The results indicated that Abamectin 0.5 % GR treated areas showed a significantly lower number of live M. graminicola compared to their untreated control. The results further indicated that the Abamectin 0.5 % GR was effective for the management of M. graminicola outbreak. Hence, it will be a greater finding for the rice farming community and it will help to reduce rice crop loss thereby helping to strengthen the food security of the country. Keywords - Abamectin 0.5 % GR, Artificial inoculation, Bio-efficacy, Outbreak, Rice root-knot nematodes (Meloidogynegraminicola)