Effect of Rice Seed Treatment with Beauveria bassiana on Salicylic Acid Content and Population of Brown Planthopper (Nilaparvata lugens Stal.)

Abstract

The brown planthopper (BPH), Nilaparvata lugens Stal., is a significant pest that adversely affects rice yields. Utilizing Beauveria bassiana (Bals.) Vuill. as a biological control agent offers a sustainable solution to combat this pest. This study investigated the impact of B. bassiana applied via rice seed treatment for 24 hours on BPH population dynamics and salicylic acid levels in rice stems. The experiment followed a completely randomized design (CRD) with five treatments and five replications, including four B. bassiana isolates (BbJg, BbWS, Pb211, Td312) and a control. A concentration of 10⁸ conidia/ml was applied uniformly across treatments. Data analysis was performed using ANOVA and LSD at a 5% significance level. Results indicated that B. bassiana treatment significantly suppressed BPH populations. The BbWS isolate demonstrated the lowest egg hatch rate (28.39%), outperforming other treatments. While the number of adult BPH remained unaffected, a notable reduction in 4th and 5th instar nymphs was observed. Furthermore, all isolates elevated salicylic acid content in rice stems, peaking at 47.87 ppm, as measured using High-Performance Liquid Chromatography (HPLC). The BbWS isolate emerged as the most effective in curbing BPH and boosting salicylic acid levels. These findings underscore the potential of B. bassiana seed treatment as an effective strategy for BPH management and enhancing plant defense mechanisms through increased salicylic acid production.