Vol. 9, Issue 6, Part B (2022)

Filariasis, transmitted by the lymphatic filariasis vector Culex quinquefasciatus, is still a global public health issue. Resistance to Cx. quinquefasciatus is caused by the eradication of filariasis with synthetic insecticides. The aim of the study was to evaluate the toxicity of pure camphor on Cx. quinquefasciatus, with a focus on detoxifying enzymes and midgut histopathological abnormalities. Cx. quinquefasciatus larvae are field-collected wild-strain larvae. The WHO protocol was followed for the larval bioassays. Pure camphor concentrations of 0.5, 1.5, 10.5, 25.5, and 50 ppm were applied to larvae for 24, 48, and 72 h, with 5 replications. The biochemical method was used to test detoxification enzymes such as acetylcholinesterase (AChE), glutathione S-transferase (GST), and oxidase. The routine histopathological examination was performed on the larvae's histopathological midguts. At 48 h, pure camphor caused 100% mortality of Cx. quinquefasciatus larvae. LC₅₀ and LC₉₀ values were found to be 2.32 and 12.40 ppm respectively. AChE and oxidase activity were both significantly lower (p<0.05). Damage to the food bolus (FB) and peritrophic membrane (PM), broken epithelial layers (EP), changes in the size and shape of epithelial cells (EC), and microvilli (Mv) damage were all observed in larval midguts. In our study, pure camphor demonstrated larvicidal activity via decreased AChE and oxidase activity, as well as midgut damage.