Nontarget effects of insecticides on biological control agents: insights from red pine forests and global challenges in forest pest management

Abstract The widespread use of insecticides in forest ecosystems has raised significant concerns about their nontarget effects on biological control agents (BCAs), such as predators and parasitoid wasps, which play a pivotal role in natural pest suppression. This review evaluates the lethal and sublethal impacts of various insecticide classes on BCAs. Systemic insecticides, while effective in controlling pests, have been shown to impair the reproduction, foraging behavior, and host-seeking abilities of BCAs, leading to disruptions in pest regulation and biodiversity loss. In Pinus koraiensis (Siebold & Zucc) forests, parasitoid wasps such as Baryscapus dioryctriae (Yang & Song) are critical for managing pests such as Dioryctria pryeri. However, insecticide exposure threatens their efficacy, exacerbating pest outbreaks and ecosystem instability. The deployment of B. dioryctriae as a BCA provides a sustainable alternative to chemical control, with demonstrated success in reducing pest populations and minimizing environmental impacts. Integrated pest management (IPM) frameworks that combine biological control with targeted insecticide use offer promising solutions to mitigate nontarget effects. Future research should focus on optimizing mass-rearing and release strategies for BCAs, exploring semiochemical-based pest disruption and assessing the long-term ecological consequences of low-dose insecticide exposure. By advancing IPM approaches, forest managers can achieve effective pest control while preserving the ecological integrity and biodiversity of forest ecosystems.