Temperature Stress Induced Phenotypic Plasticity of Spodoptera litura (Lepidoptera: Noctuidae)

Spodoptera litura (Fabricius), a highly damaging polyphagous pest, significantly affects crops in temperate and sub-tropical regions. This study investigates the impact of thermal stress exerted across different developmental stages on the phenotypic plasticity of S. litura, focusing on adult body size and weight. Field populations were reared in controlled conditions (27±1°C) and subjected to two higher temperature stress (42 ºC for 4 hours) and (46 ºC for 1 hour) for short and long-term duration. Results showed significant reductions in body size and weight of both male and female adults under increased temperature and duration of exposure. Exposure of early developmental stages viz., eggs and larvae resulted in severe reduction of size and weight in adults of female and male respectively. These findings indicate that early developmental stages are more susceptible to thermal stress, likely due to critical growth periods. The study highlights the vulnerability of S. litura to extreme temperature fluctuations and underscores the ecological implications of climate change on insect populations. Elevated temperatures lead to adaptive responses prioritizing survival over growth and development. Understanding these responses is crucial for developing sustainable pest management strategies and enhancing agricultural resilience amidst global climate challenge.