Cholinestérase et toxicité des extraits aqueux de Pergularia tomentosa L. chez les larves de Culex pipiens Linnaeus, 1758.

Abstract

The aim of this study is to evaluate the insecticidal activity of aqueous extracts from Pergularia tomentosa L. leaves against Culex pipiens mosquitoes. The extraction yield from the leaves is 9.29%. The results obtained demonstrate a toxicity effect on L4 larvae treated with different doses of the Aqueous plant extract. Toxicity tests are conducted using various doses of the aqueous extract of Pergularia tomentosa L. (25%, 50%, 75%, and 100%), and 0% for the witnesses. allowing for the determination of mortality rates, DL50 and DL90, TL50 and TL90. Biochemical tests are then performed to determine the cholinesterase activity and specific activity. The corrected mortality rate is highest in larvae treated with the highest dose (100%), resulting in complete mortality after 2 days of exposure. The calculated DL50 is 1.0505 mg/ml and DL90 is 4.467 mg/ml. The shortest lethal time (TL50) is recorded in larvae treated with the highest dose of 100%, with TL50 is 9.12 hours compared to other dilutions, and the shortest TL90 is recorded in larvae treated with the highest dose of 100%, with TL90 is 29.51 hours compared to the dilutions. The cholinesterase enzyme activity increases with increasing dose of Pergularia tomentosa L. extract, and the maximum enzyme activity is observed in larvae treated with the dose of 100% of the aqueous extract after 1 hour and 24 hours of exposure, with values of 22.63±0.90 µmol/min/ml and 31.53±2.56 µmol/min/ml respectively. Similarly, the specific enzyme activity also increases with increasing dose of Pergularia tomentosa L. extract. The maximum enzyme activation is noted in larvae treated with the dose of 100% of the aqueous extract after 1 hour and 24 hours of exposure, with values of 3.450±0.17µg/min/µg of protein and 4.806±0.68 µg/min/µg of protein respectively, The analysis of the variance shows a significant effect of the applied dose on the larvae, also a positive and very significant correlation exists between the mortality and the activity of the enzyme cholinesterase.

The results of the insecticidal activity demonstrate the effectiveness of aqueous leaf extracts of Pergularia tomentosa L. against Culex pipiens