Thermal thresholds and life table analysis of Helicoverpa armigera (Hübner): a case study on chickpea

Helicoverpa armigera (Hübner) is a major lepidopteran pest of chickpea, with its development and reproduction strongly influenced by temperature. This study examined the development, survival and reproduction of H. armigera reared on chickpea under constant temperatures ranging from 14°C to 36°C. Life table parameters were estimated along with linear and six non-linear thermal models to identify critical thresholds and heat requirements. Results showed that fecundity peaked at 27°C (532 eggs/female) and declined at higher temperatures, while the intrinsic rate of increase (rm) was highest at 30°C. Linear regression analysis estimated the lower temperature threshold (Tmin) for egg development at 7.71°C, while Tmin for larval instars ranged from 4.19°C to 10.52°C. Embryonic development required 74.07 degree-days. Among the six non-linear temperature development models tested, the Lactin-2 model yielded the most biologically realistic estimates of Tmin, optimal temperature (Topt), and upper threshold (Tmax), and showed the best goodness-of-fit based on AIC and related statistics. These results provide reliable temperature-based developmental and phenological models for H. armigera on chickpea, supporting better prediction of pest population dynamics and more precise timing of integrated pest management under variable climatic conditions.