Analysis of Mortality Factors Affecting Brown Planthopper, Nilaparvata lugens (Stål, 1854) Population as Rice Field Life Tables

Abstract

Nilaparvata lugens (Stål) is a significant insect pest of rice and its population under field conditions is regulated by natural factors. Ecological or field life table analysis is an effective tool for estimating the mortality caused by these factors. In the present study, cohort based ecological life tables were constructed to evaluate the mortality caused by abiotic and biotic factors across three rice phenological stages: active tillering, panicle bearing-grain filling and grain maturity. Egg sterility, high temperature, predation, parasitism and incomplete moulting were identified as the major mortality factors, with early nymphal instars (1-3) being the most susceptible. The key mortality factor was predation by arthropods such as spiders, coccinellids and bugs. This study provides quantitative, stage-specific insights into mortality dynamics, highlighting the dominant role of predation and the vulnerability of early nymphal stages in regulating N. lugens populations under field conditions.