Toxicity assessment of mixtures of plant-based compounds against Aedes albopictus larvae and non-target larvivorous fish Trichogaster fasciata

Urbanisation and modern aesthetic practices have increased the use of container gardening, aquariums and overhead water tanks in households. Although these water containers enhance urban living, they also serve as ideal breeding sites for the invasive Asian tiger mosquito Aedes albopictus , a dengue vector. In the search of a sustainable alternative to synthetic insecticides, although plant-based insecticides are explored, appropriate dose optimization is essential to minimize negative non-target effects. This study aimed to screen binary larvicidal combinations using diallyl disulfide, D-limonene and α-pinene against A. albopictus larvae, and to evaluate non-target toxicity to the native larvivorous fish Trichogaster fasciata . Diallyl disulfide + D-limonene showed the highest synergy and caused a significant inhibition of larval detoxification enzymes. α-Pinene also displayed synergism in LC 50 :LC 50 mixtures with both compounds, while the 1:1 mixture produced additive effects. Morphological and histopathological analysis demonstrated integumental melanisation and midgut tissue disruption in treated larvae. Molecular docking of these compounds revealed that α-pinene and D-limonene showed higher binding affinities toward glutathione s-transferase, Cytochrome P450 and esterase, forming Pi-alkyl, Pi-sigma and Van der Waals interactions. Non-target test revealed that LC 25 of all combinations were safe for T. fasciata , while only the LC 50 of D-limonene + α-pinene was non-toxic. Diallyl disulfide-containing combinations at LC 50 , showed mild gill alterations highlighting the need for caution at higher concentrations. Overall, at optimized concentrations, these combinations show promise as potential eco-friendly larvicidal candidates for controlling A. albopictus in urban water containers.