Effects of Temperature on Life-History Traits of Paralipsa gularis (Zeller) (Lepidoptera: Pyralidae), a Newly Emerged Maize Pest from the Border Areas Between China and Southeast Asian Countries

Paralipsa gularis (Zeller) (Lepidoptera: Pyralidae) is a storage pest native to Southeast Asia that has since spread to Northern Europe, North America, and other parts of Asia. In recent years, it has become an increasingly destructive pest in maize agroecosystems along the China–Southeast Asia border region, causing severe damage. Temperature is a key environmental factor influencing insect development, fecundity, and distribution, yet its effects on P. gularis remain unclear. In this study, we used an age-stage two-sex life table to evaluate the effects of temperature on the development duration, survival, and fecundity of P. gularis. We also determined the developmental threshold temperatures and effective accumulated temperatures for each life stage and developed a predictive model of developmental duration. Our results showed that temperature significantly affected the development duration across all stages, as well as larval and pupal survival rates and adult fecundity. Temperatures of 15–20 °C and 33–35 °C were unsuitable for population development, whereas 23–30 °C was optimal. At 15 and 35 °C, P. gularis failed to reach the pupal stage; at 33 °C, only a very few individuals reached adulthood. Between 18 and 30 °C, the development duration of each stage decreased with increasing temperature, with larval development ranging from 69.81 to 14.92 days. The optimal temperature was 28 °C, at which the insects exhibited high body weight, survival rate, intrinsic rate of natural increase (r), finite rate of increase (λ), and net reproduction rate (R0). The developmental threshold temperatures for eggs, larvae, pupae, and the overall generation were 17.33, 14.03, 11.72, and 13.11 °C, respectively, and the effective accumulated temperatures were 33.49, 242.51, 116.26, and 524.93 degree-days, respectively. This study provides a scientific basis and technical support for predicting population dynamics under varying climatic conditions and for developing effective control strategies for P. gularis.