TOXICITY OF CERTAIN PLANT EXTRACTS ON CULEX PIPIENS LARVAE (DIPTERA: CULICIDAE) UNDER LABORATORY CONDITIONS.

To minimize the negative impacts of chemical insecticides on public health, eight extracts (ethanolic – aqueous) of four plants were determined against the 3rd larval instar of Culex pipens. After 24 h of treatment, the eight plant extracts showed larvicidal activity with LC50 values of 357, 519, 569, 579, 717, 2268, 2371 and 2544 ppm for ethanolic Allium sativum, aqueous Allium sativum, ethanolic Punica granatum, ethanolic Nerium oleander, aqueous Nerium oleander, aqueous Punica granatum, ethanolic Cinnamomum camphora and aqueous Cinnamomum camphora, respectively. The tested extracts resulted a significant effect on total proteins, total carbohydrates, acetylcholinesterase (AChE), α-esterase, β-esterase and glutathione S- transferase (GST) in the treated larvae. The treated 3rd larval instar of Cx. pipiens were affective to all tested plant extracts and showed remarkable change of metabolic rate comparing with untreated control. All plant extracts reduced total proteins and total carbohydrates content. The highest effect was recorded with Ethanolic A. sativum. Ethanolic P. granatum and ethanolic A. sativum increased the activity of AChE, GST, α-estrases and β-estrases while the aqueous A. sativum decreased the activity of GST, α-estrases and β-estrases. Aq. P. granatum decreased the activity of AChE. The results show that the tested plant extracts used were possible promising as a larvicidal agents against Culex pipiens, naturally occurring biopesticide could be an alternative for chemical insecticides.