Life Table Analysis of Nephus includens (Coleoptera: Coccinellidae) Feeding on Planococcus citri at Constant Temperatures

Abstract

The effectiveness of biological control agents in suppressing mealybug populations is strongly influenced by environmental temperature, necessitating detailed life table analysis for optimizing field application strategies. The present study evaluates the life table parameters of the predatory beetle Nephus includens (Coleoptera: Coccinellidae) when reared on Planococcus citri under constant temperature regimes. Developmental duration, survival rate, fecundity, and reproductive potential were recorded at multiple temperature treatments under controlled laboratory conditions. Results indicated that temperature significantly influenced all biological parameters of the predator. Developmental time decreased progressively with increasing temperature up to an optimal threshold, beyond which survival and reproductive output declined. Maximum survival and fecundity were observed at intermediate temperatures, reflecting favorable physiological performance and efficient prey utilization. Life table analysis revealed that net reproductive rate (R₀), intrinsic rate of increase (r), and finite rate of increase (λ) were highest at optimal thermal conditions, indicating strong population growth potential of the predator under suitable environmental settings. Conversely, higher temperatures resulted in reduced longevity and lower reproductive success, suggesting thermal stress effects on biological efficiency. Mean generation time (T) decreased with rising temperature, demonstrating accelerated development cycles under warmer conditions. These findings highlight the temperature-dependent performance of N. includens as a biological control agent against P. citri. The study emphasizes the importance of aligning predator release programs with favorable thermal windows to maximize pest suppression efficiency. Overall, N. includens exhibits strong potential as an effective natural enemy of citrus mealybugs, and its population dynamics are closely regulated by temperature, which should be considered in integrated pest management strategies for sustainable citrus protection systems under varying climatic conditions.