Larvicidal effect and mechanism of action of the essential oil and major compound from Piper brachypetiolatum (Piperaceae) against Aedes aegypti (Linnaeus, 1762) larvae, with protection of non-target aquatic animals

Botanical larvicides like essential oils (EO) and their main compounds extracted from plants, such as those in the Piper species offer eco-friendly approaches to mosquito control on account of promote activity against Culicidae larvae, while demonstrating low toxicity to non-target aquatic animals. This study investigated the mechanism and larvicidal activity of the essential oil from Piper brachypetiolatum and its main compound against Aedes aegypti, as well as the lethal effects on the non-target aquatic organisms Toxorhynchites haemorrhoidalis, Anisops bouvieri, and Diplonychus indicus. The EO was extracted from the leaves of P. brachypetiolatum using the hydrodistillation method, yielding 1.5 ± 0.7%. Gas chromatography analyses revealed the presence of sesquiterpenes (64.70%), oxygenated sesquiterpenes (17.64%), monoterpenes (11.76%), and oxygenated monoterpenes (5.88%). The major compound identified was (E)-nerolidol, comprising 64.32% of the EO. Both EO and (E)-nerolidol exhibited larvicidal activity against A. aegypti, with LC50 values of 15.51 and 9.50 ppm, respectively. They also inhibited AChE activity, with IC50 values of 44.97 and 11.07 ppm, respectively, and induced RONS overproduction (p < 0.05) compared to the positive control, α-cypermethrin. Additionally, EO and (E)-nerolidol showed no lethal effects on T. haemorrhoidalis, A. bouvieri, and D. indicus, with these species exhibiting 100% survival after exposure. In contrast, α-cypermethrin caused 100% mortality in these species. These findings highlight the promising potential of the EO from P. brachypetiolatum and (E)-nerolidol as effective and safe alternatives for controlling A. aegypti larvae.