A STUDY ON THE EFFECT OF CONSTANT AND FLUCTUATING TEMPERATURES ON SOME ASPECTS OF BIOLOGY OF NILAPARVATA LUGENS (STAL) AND NEPHOTETTIX VLRSSCEMS (HORV

Abstract

ITilaparyata lup.SiQS (Stal) and Nephotettix vires cons (Horv ) are the two major rice pest in Bangladesh, Temperature response of these two species was studied in the laboratory. The f avourable range of temperature for preoviposition period was 30®C-l+0®C for both the species. The incubation and developmental period was found to be shortest at i+0®C. The maximum and minimum adult longevity ware at 2?®C and 1+0°C respectively. The maximum hatchability was observed at 30°C and minimum at 20®C in both the species. The maximum survival!ty from egg to adult stage was found in 30°C in 21. lumens and 2?®C in virescens. The duration of the larval periods were 30 days at 20°C in 2J. virescens and 31 days in £[• lunens at the same temperature. The egg viability was maximum in 25°C to 3°°C and minimum at 20®C, The time required for hatching of eggs of both the species was almost same. At 10 and b5°G the development of eggs and larvae did not occur. The time required for development of eggs and larvae was more at fluctuating temperature than the constant temperature