Sub-lethal and population-level impacts of afidopyropen and flonicamid on Harmonia conformis (Coleoptera: Coccinellidae)

Insecticides that selectively target pests while preserving natural enemies are essential for Integrated Pest Management (IPM) programs. This study investigated the effects of two 'selective' insecticides, afidopyropen and flonicamid, alongside a broad-spectrum insecticide, gamma-cyhalothrin, on the predatory ladybird Harmonia conformis (Coleoptera: Coccinellidae). Acute toxicity was assessed following International Organisation for Biological Control (IOBC) guidelines, and supplemented with further investigations into sub-lethal and population-level impacts. Gamma-cyhalothrin caused 100 % mortality within 24 h, classifying it as 'harmful' under IOBC guidelines. In contrast, afidopyropen and flonicamid caused minimal acute mortality in H. conformis and were classified as 'harmless', and had no observable effects on longevity, development rates or population growth. Despite this, sub-lethal assessments showed that both insecticides significantly reduced feeding rates and fecundity, suggesting that they may still impair the ability of H. conformis to effectively control aphid populations in the field. Overall, the study highlights the importance of assessing sub-lethal impacts of insecticides to thoroughly understand their effects on biological control agents. This knowledge can be used in IPM programs to balance pest management with the conservation of natural enemies.