Enzymatic Changes in the Larvae of Culex pipiens L., 1758 (Diptera: Culicidae) Induced by Nanoemulsion of Pimpinella anisum L. Essential Oil

Culex pipiens is a common mosquito species that transmit many important diseases. Formulation of new natural insecticides extracted from plants by the help of nanotechnology offers a new gate to control such a very important medical insect pests away from the hazardous synthetic insecticides. The nano-size add improved characteristics to the materials including insecticides, such as a greater surface area and a better penetration ability of the insecticides into the tissues of the target insect pest.The objective of the current investigation is to evaluate the larvicidal influence of nanoemulsion containing Pimpinella anisum essential oil on the larval enzymes responsible for insecticides detoxification. The quantitative measurements of enzymes acetylcholinesterase, glutathione-S-transferase, and α-esterase were performed after exposing third instar larvae of Culex pipiens to LC50 of the nanemulsion for 24 hours. The results obtained from this investigation indicated a neurotoxic activity and significant disruption of activity of the detoxification enzymes as proved by decreasing level and inhibition of acetylcholinesterase activity in the treated larvae compared with control samples. While, glutathione-S-transferase and α-esterase enzymes showed a significant increase in the treated larvae compared to the enzyme level in the control larvae.The current study showed encouraging insecticidal activity of essential oil of Pimpinella anisum against Culex pipiens larvae. In conclusion, the tested nanoemulsion proved to have insecticidal and disruptive effect on the enzymes of Culex pipiens larvae. So, it can be applied effectively in the management program to control the disease vector Culex pipiens in the breeding sites where the larval stage lives.