Transgenerational effects of short-term low-temperature stress on development, fecundity, and cold tolerance of Megabruchidius dorsalis

Abstract

Megabruchidius dorsalis (Fåhraeus) (Coleoptera: Chrysomelidae) is a key field and storage pest of Gleditsia sinensis seeds. This study investigated the transgenerational effects of short-term low-temperature stress (5 °C and 10 °C for 1, 3, and 5 days) on the development, fecundity, and cold tolerance of M. dorsalis. The results showed that low-temperature stress significantly prolonged the pre-oviposition of the parental (P) generation and extended adult longevity, indicating a survival-fecundity trade-off strategy. In the F₁ generation, exposure to 10 °C for 1, 3, or 5 days notably extended the egg period, delayed reproductive timing and reduced total fecundity, revealing transgenerational effects. Adult longevity of F₁ generation was significantly influenced by temperature, stress duration, and their interaction, with distinct patterns between mated and unmated individuals and between sexes. The supercooling point (SCP; temperature at which spontaneous nucleation and ice lattice growth begin), increased with prolonged exposure at 5 °C. However, SCP and freezing point (FP; temperature at which insect fluids freeze) decreased under 10 °C treatment with exposure durations from 3 to 5 days. But, neither treatment significantly affected the SCP and FP of F₁ adults. These findings provide novel insights into the life-history adaptations and short-term cold-tolerance strategies of M. dorsalis, highlighting the importance of transgenerational responses for forecasting population dynamics under fluctuating temperature conditions and informing temperature-based pest management strategies.