Distinct Resistance Groups in Rice Germplasm from Kerala Based on Antibiosis and Tolerance Traits to Brown Planthopper, Nilaparvata lugens (Stal)

Abstract

Background: Brown planthopper (Nilaparvata lugens) is a major insect pest of rice that causes severe yield losses through direct feeding and hopperburn. The emergence of virulent populations and increasing concerns over insecticide resistance necessitate the identification of rice germplasm with effective host plant resistance for sustainable pest management. Aims: To identify rice germplasm accessions resistant to N. lugens by evaluating antibiosis and tolerance mechanisms and to classify the accessions based on their resistance responses. Study Design: Comparative laboratory screening of rice germplasm accessions using antibiosis and tolerance parameters, followed by multivariate analysis. Place and Duration of Study: Department of Agricultural Entomology, Kerala Agricultural University, Thrissur, Kerala, India, during 2023–2025. Methodology: Twelve rice germplasm accessions, together with the resistant check PTB 33 and susceptible check TN 1, were evaluated under controlled conditions. Antibiosis and tolerance were assessed using standard biological and plant response parameters. Data were analysed using analysis of variance, Spearman correlation, principal component analysis, and hierarchical clustering. Results: Significant differences were observed among the germplasm accessions for all antibiosis and tolerance parameters (P < .001). TGC 108 and UN 46 22K exhibited lower honeydew excretion (27.2 and 28.4 mm²), reduced nymphal emergence (99.4 and 114.6 nymphs/accession), prolonged developmental periods (21.2 and 19.4 days), delayed wilting (25.0 and 22.7 days), and lower functional plant loss index values (22.7 and 25.2), indicating strong antibiosis and tolerance. Principal component analysis explained 97.02% of the total variation, and hierarchical clustering grouped the germplasm into three distinct resistance categories. Conclusion: TGC 108 and UN 46 22K exhibited strong antibiosis and tolerance responses and emerged as promising donor sources for the development of brown planthopper-resistant rice varieties.