Temperature-dependent response of diapause termination in emerald ash borer (Coleoptera: Buprestidae): implications...

The emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), native to Northeast Asia, is the most destructive invasive pest of ash (Fraxinus spp.) in North America. In this study, we exposed mature fourth-instar diapausing EAB larvae (J-shaped or J-larvae) to nine temperatures ranging from 1.7 to 23.9 °C for 90 days, and then evaluated their diapause termination by measuring both the probability and timing of post-chill development to adults under warm rearing conditions (27 ± 0.5 °C, 16:8 h L: D). We also determined the effect of chill temperature on the mortality of diapausing J-larvae. Results showed that J-larvae successfully completed diapause after exposure to temperatures between 7.2 and 15.6 °C for 90 days and chill treatment significantly affected the duration required for post diapause development to adult emergence, with the mean number of days required for adult emergence increasing as chill temperature increased. In addition, the mortality rate for the EAB larvae that died at the J-larval stage before completing diapause development to adults was lower (0% to 7.1%) for temperatures between 1.7 and 12.8 °C than that (16% to 32.6%) for temperatures between 15.6 and 23.9 °C. These results refine our understanding of the thermal limits for EAB diapause termination and provide insight into how climatic conditions may influence EAB phenology and distribution across its geographic range.