Effects of Elevated Carbon Dioxide and Temperature on Rice Brown Planthopper, Nilaparvata lugens (Stal) Populations in India

Two populations of the brown planthopper (BPH), Nilaparvata lugens (Stål) (Hemiptera: Delphacidae) were collected from two hotspot locations of India – Ludhiana (Punjab) in the north and West Godavari (Andhra Pradesh) in the south, and their biological parameters were studied under ambient conditions. Results showed that the above two populations were notably different in three out of five biological parameters recorded. The response of these two populations to climate variables, viz. elevated temperature and increased levels of CO₂ was assessed. These conditions prolonged the nymphal duration (14.2 days) and lowered female longevity (9.6 days), fecundity (155.5 eggs/♀) and nymphal feeding rate (14.3 mm²)) compared to ambient CO₂ and temperature across the populations. Honeydew excretion by adults was significantly higher at elevated CO₂ than at ambient level. At elevated CO₂ and higher temperature, the Ludhiana population recorded significantly longer nymphal duration (15.9 days) and decreased amount of honeydew excretion by nymphs (13.8 mm²) compared to the parameters recorded at elevated CO₂ and ambient temperature (12.8 days and 32.8 mm²) respectively). In contrast, West Godavari population recorded significantly reduced female longevity and fecundity under elevated CO₂ and higher temperature. Elevated CO₂ per se did not adversely affect BPH biology across populations but with the concomitant increase in temperature, populations showed varying response. Location-specific mitigation strategies for management of hoppers will be required to address the varying responses of populations to climate variables.