Contact in-vivo larvicidal toxicity and histological studies of Indian herb essential oils loaded niosomes against Aedes aegypti and Culex quinquefasciatus (Diptera: Culicidae)

The need for eco-friendly plant-based products has gained enormous attention. In this study, attempts were made to develop niosomes encapsulated with Indian herb oils using the transmembrane pH gradient method and evaluated for their mosquito larvicidal properties. The bioactive constituents in herb oils were analyzed using Gas Chromatography-Mass Spectrometry. The synthesized niosomes were characterized using Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, Zeta-Sizer and Zeta-Potential. The average size of neem oil, eucalyptus oil and rosemary oil encapsulated niosomes were identified to be 912.36 nm, 693.25 nm and 869.64 nm, respectively with good stability. The data obtained from mortality rate analysis against mosquito larvae with the synthesized niosomes were evaluated using probit analysis statistical method. The LC50 and LC90 values for neem oil, eucalyptus oil and rosemary oil encapsulated niosomes treated against Aedes aegypti larvae were 36, 59 ppm, 41, 79 ppm and 43, 72 ppm, respectively and treated against Culex quinquefasciatus larvae were 33, 71 ppm, 35, 75 ppm and 45, 80 ppm, respectively. In light of the above, it was found that neem oil loaded niosomes had better larval mortality rate. Histological analysis of dead larvae revealed the damage in the epithelial cells of midgut region of larvae, which led to mortality. The study suggested that Indian herb oil-based niosomes could be used as an alternative to synthetic mosquito larvicides.