Temperature-dependent toxicity of insecticide chlorantraniliprole (Altacor®) in the aquatic primary producers Raphidocelis subcapitata and Lemna minor

Anthropogenic activities and climate change are intensifying multiple environmental stressors that may interact and threaten aquatic ecosystems. Among these, pesticides represent a major concern due to their frequent detection in surface waters. This study evaluated the combined effects of the insecticide chlorantraniliprole (CAP; the active ingredient of Altacor®), and elevated temperature on two standard aquatic primary producers: the microalgae Raphidocelis subcapitata and the macrophyte Lemna minor . Organisms were exposed to a range of CAP concentrations (0.007–10.5 mg L -1 ) at 24 ± 1 °C (standard condition) and 28 ± 1 °C (projected climate change scenario). Relative growth rates, photosynthetic pigments (chlorophylls and carotenoid contents), and oxidative stress biomarkers (catalase activity and lipid peroxidation) were measured. Temperature significantly modulated CAP toxicity, with interactions between both factors for most endpoints evaluated. R. subcapitata showed minimal growth inhibition but significant alterations in pigment content, whereas L. minor exhibited moderate to high physiological and biochemical effects, particularly enhanced catalase activity and lipid peroxidation at 28 °C. An increase in temperature generally intensified oxidative stress and pigment imbalances. Overall, these findings highlight significant temperature-dependent interactions between pesticide exposure and warming, posing risks to primary producers and, consequently, aquatic food webs. The results reinforce the need to integrate climate-related variables into environmental risk assessments and to promote more sustainable pesticide management under global warming scenarios.