Temperature and relative humidity mediated life processes of Spodoptera species (Lepidoptera: Noctuidae)

Anthropogenic-mediated climate change is expected to negatively affect pest management in agriculture. Hence, we investigated the oviposition, immature mortality, and developmental processes of Spodoptera species (Spodoptera exigua (Hübner) and Spodoptera litura (Fabricius)) under different temperatures (20, 25, and 30°C) and relative humidity (RH) (30-35, 50-55, 70-75, and 90-95%) conditions. For fecundity, mouths of each Spodoptera species were released into a rectangular box whose inner walls were covered with a sheet of white paper for each combination of temperature and RH. The mouths were kept inside the box to deposit eggs for 72 h. Temperature and RH significantly affected the fecundity, with the maximum number of eggs laid in 70-75% at 30°C. The highest egg and larval mortalities were recorded in 30-35 and 90-95% RH, respectively. Temperature and RH greatly affected the developmental period (egg-adult) and adult emergence rate. The rapid development was recorded in 70-75% RH at 30°C. Higher number of adults was found with an increase in temperature and RH. Adult longevity was significantly higher in 70-75% RH at 20°C. Based on the present study's findings, temperature and RH had an individual apparent effect on the developmental processes of Spodoptera species instead of an interactive effect. Therefore, there is need for an in-depth study of the influence of several climatic factors, including CO₂, on the developmental modality and demographic changes of Spodoptera species to assess the impacts of climatic components and the sustainable development of management strategies.