Impacts of elevated carbon dioxide on the development and reproductive biology of Choristoneura fumiferana (Lepidoptera: Tortricidae)

Rising atmospheric carbon dioxide (CO₂) concentrations are a major driver of climate change, posing a significant challenge to global ecosystem functions. This challenge is compounded by the potential effects of elevated CO₂ on forest pest insects like the eastern spruce budworm (Lepidoptera: Tortricidae), a major mortality agent in Canadian boreal forests. To better understand these impacts, this study investigates how elevated (1000 ppm) and ambient (469 ppm) CO₂ concentrations affect budworm development across different life stages. In vitro experiments revealed that budworms exposed to the elevated CO₂ concentration exhibited accelerated development, with increased larval weight gain from third to sixth instars, faster pupation and adult emergence, and earlier oviposition compared to those exposed to the ambient condition. However, elevated CO₂ concentration led to reduced realised fecundity. These findings highlight the direct impact of elevated CO₂ concentrations on budworm biology, with important implications for its role in forest ecosystems under climate change.