Seasonal activity of rice brown planthopper, Nilaparvata lugens (stal) (Homoptera: Delphacidae) in sub-mountainous region of Punjab

Field studies regarding seasonal activity of brown planthopper (BPH) in rice were carried out during Kharif 2018 and 2019 in four villages of sub-mountainous region of Punjab. Results revealed that pest started appearing in the month of August and continued till harvest of the crop. The population varied between 0 to 24.6, 0 to 21.8, 0 to 26.2 and 0 to 23.2 hoppers/hill in villages Ballowal, Saunkhri, Rattewal and Takarla, respectively during Kharif 2018. Similar trend was observed in Kharif 2019 but incidence was comparatively less with population varying from 0 to 18.8, 0 to 14.4, 0 to 19.20 and 0 to 20.40 hoppers/hill in villages Ballowal, Saunkhri, Rattewal and Takarla, respectively. The pest population reached above the economic threshold level (>5 hoppers/hill) in second week of September (37th SMW) and the peak population was observed during fourth week of September (39th SMW) during Kharif 2018 in Ballowal, Saunkhri and Takarla while in village Rattewal, the pest reached above economic threshold level in the third week of September (38th SMW). During Kharif 2019, the BPH reached above economic threshold level in the third week of September (38th SMW) and the peak population was observed during fourth week of September (39th SMW) in Ballowal, Saunkhri, Rattewal and Takarla. A constant decline in the pest population was observed thereafter. The correlation worked out between different weather parameters and BPH population revealed non-significant negative correlation with minimum and maximum temperature, evening relative humidity and rainfall, whereas, positive and non-significant correlation was found with morning relative humidity. The results obtained reveal abundance of the pest populations on paddy crop and appropriate time for initiation of plant protection measures on need basis.