Abstract
Temperature driven development of rice brown planthopper (BPH), Nilaparvata lugens (Stål) (Hemiptera: Delphacidae) population (biotype 4) was examined at seven constant temperatures (15, 18, 20, 25, 30, 32 and 35°C). Complete development of BPH from egg to adult was observed at constant temperatures ranging from 15 to 32°C with linear development observed till 30°C. Total immaturedevelopmental duration decreased from 74.4 days at 15°C to 22.4 days at 30°C. Linear and non-linear models fitted to describe developmental rates of life stages as a function of temperature, gave estimates of bioclimatic thresholds (lower, optimum and upper temperature thresholds). Thermal constants estimated from Campbell linear model for egg, nymph and cumulative immature development to adult were, 198.8, 275.5 and 473.9 degree days, respectively. Among empirical non-linear models, Lactin 2 model was selected for estimates of upper temperature threshold at 35°C based on higher coefficient of determination. Application of thermodynamic SSI model explained the observed nonlinear relationship of development of BPH life stages at temperatures higher than 30°C. The estimated thermal constants and bioclimatic thresholds were used in developing temperature dependent phenology model based on Campbell equation. Phenology model predicted closely the occurrence of different life stages of BPH with those observed under field conditions.
Highlights
Brown planthopper (BPH), Nilaparvata lugens (Stål) (Hemiptera: Delphacidae) is the most destructive insect pest in the lowland irrigated rice ecosystem of tropical Asia
Temperature dependent phenology models were developed by using the estimated thermal constants and bioclimatic thresholds which helps in the prediction of seasonal dynamics of the pest in various agroecological zones of India
We developed phenology model based on linear Campbell model and predicted timing of different life stages in the field by computing accumulated degree days (ADD) starting from the first date of appearance of adult in the field
Summary
Brown planthopper (BPH), Nilaparvata lugens (Stål) (Hemiptera: Delphacidae) is the most destructive insect pest in the lowland irrigated rice ecosystem of tropical Asia. Previous studies from different countries reported only the optimum conditions, maximum and minimum tolerance limits of temperature and RH in relation to biological parameters of BPH (Lu et al, 1999) and estimation of lower developmental thresholds (Krishnaiah et al, 2005). There are no reports on nonlinear relationship between rate of development of the pest and higher temperatures which can be used to estimate the optimum and upper threshold. In the present study, the effect of different constant temperatures on development and survival of the pest was studied, two linear and three non-linear models were applied to estimate thermal constants and bioclimatic thresholds of BPH.
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