Brown plant hopper (BPH) outbreak in rice: Analysis of weather parameters during outbreak and Non-Outbreak years

Brown plant hopper (BPH), Nilaparvata lugens (Stal.) population was observed to be in outbreak proportions at 542.0 and 756.9 hoppers/hill during 2008 and 2013, respectively, compared to 2.5–62.5 hoppers/during non-outbreak years. Weather parameters viz., total weekly rainfall (mm), weekly number of rainy days, daily morning, evening and mean relative humidity-RH (%), daily maximum, minimum and mean temperature (°C) and daily sunshine hours during 1998–2013 were analysed. There existed maximum similarity during 2008 and 2013 with regard to weather factors, particularly number of rainy days and relative humidity; minimum temperature also did not differ significantly. Besides other factor, well distributed rainfall during June-September with more number of rainy days (> 30) that led to higher RH during 2008 and 2013 might have favoured faster multiplication of BPH, leading to its outbreak. Forecast on rainfall frequency during monsoon months can provide an important clue about likely scenario of BPH incidence.