Age-Specific Life Table Analysis of Spodoptera exigua Fed on Different Cultivars of Bean Under Controlled Conditions

Abstract

The beet armyworm, Spodoptera exigua, is a polyphagous lepidopteran pest causing extensive damage to leguminous crops, particularly bean cultivars, through defoliation and reduced plant vigor. Understanding its population growth parameters under different host plant conditions is essential for predicting pest outbreaks and improving management strategies. The present study evaluated the age-specific life table parameters of S. exigua fed on different bean cultivars under controlled laboratory conditions. Developmental duration, survival rate, fecundity, and longevity were recorded across successive life stages to construct detailed life tables for each cultivar. The results demonstrated significant variation in biological performance of S. exigua depending on bean cultivar. Certain cultivars supported faster larval development, higher survival rates, and increased fecundity, indicating greater host suitability for pest population growth. In contrast, less suitable cultivars resulted in prolonged developmental periods, reduced adult emergence, and lower reproductive output. Age-specific survival curves showed higher mortality during early larval stages on resistant cultivars, contributing to reduced population growth potential. Key demographic parameters, including net reproductive rate, intrinsic rate of increase, and finite rate of increase, varied significantly among cultivars, reflecting differences in host plant quality and nutritional suitability. The findings highlight the strong influence of host plant genotype on the population dynamics of S. exigua. This study provides valuable insights into host–pest interactions and supports the use of resistant bean cultivars as a component of integrated pest management strategies aimed at reducing pest pressure and minimizing crop losses under field conditions.