Effect of Temperature on the Cohort Life Table of Brown Planthopper (Nilaparvata lugens Stål) (Homoptera: Delphacidae)

Abstract

We investigated the effect of constant temperatures (24, 28, 32, and 36 °C) and room temperature on brown planthopper (BPH), Nilaparvata lugens, population dynamics; these data are useful for forecasting BPH outbreaks. Eggs laid by gravid females were incubated in test tubes at the treatment temperatures and observed for egg hatching. After hatching, first instar nymphs were collected using a camel-hair brush and incubated individually in new test tubes, each with a rice plant. The number of hatched and unhatched eggs were recorded. Nymphs were monitored daily for life table parameters until adult emergence; the longevity of adults were also recorded. From life table analysis, the greatest mortality occurred in the first nymphal instar, which resulted in type III survivorship curves. Moreover, at 36 °C, 100% mortality occurred at the egg stage. Brachypterous and Macropterous forms achieved high net reproductive rates at lower temperature regimes. The growth parameters of BPH decreased at 36 °C; temperatures above 32 °C were detrimental to the development of BPH. Results indicate that egg and nymphal stages were significantly affected by temperature. Egg hatch also decreased drastically with increased temperatures, especially at 36 °C.