Potential of Eugenol for Eco-friendly Control of Aedes albopictus (Diptera: Culicidae) in an Integrated Model with Non-target Organism.

Eugenol, a major constituent of clove and basil essential oils, has gained attention for its insecticidal properties, particularly against Aedes aegypti Linnaeus, suggesting potential effectiveness against other Aedes species. Aedes albopictus (Skuse) (Asian tiger mosquito) is a rapidly spreading invasive species responsible for transmitting serious diseases, including dengue. In the present study, we evaluated eugenol's larvicidal activity against A. albopictus larvae and its impact on the non-target larvivorous fish, Trichogaster fasciata. Eugenol showed larvicidal activity with an LC₅₀ of 149.89 ± 17.38 ppm, while clove oil had a lower LC₅₀ of 77.11 ppm at 24 h. Eugenol exposure resulted in notable larval morphological changes, including melanization of the thorax and anal papillae. Histopathological analysis revealed toxic effects of eugenol on the peritrophic membrane, epithelial layer and microvilli of the larval midgut after 24 h. We also assessed the acute toxicity of eugenol on T. fasciata over 96 h using LC₁₀, LC₂₅ and LC₅₀ concentrations. LC₁₀ and LC₂₅ concentrations were safe for the fish, but LC₅₀ caused immediate mortality. Remarkably, LC₂₅ concentration restored the natural pigmentation of T. fasciata, which had been lost in aquarium acclimatized conditions. Histopathological examination revealed normal gill and liver features in fish exposed to LC₂₅. In an integrated model, eugenol at LC₂₅ effectively killed A. albopictus larvae and did not harm the non-target larvivorous mosquito Toxorhynchites splendens Theobald and fish T. fasciata. Thus, eugenol (LC₂₅) shows promise for controlling A. albopictus larvae in small aquariums and nursery ponds, alongside beneficial larvivorous species.