Effect of three plant extracts on egg hatchability and larval development of Culex pipiens L. [electronic resource].

Includes references.

The activity of methanolic plant extracts from Rhazya stricta Cleo me paradoxa and Heliotroblum bacciferum has been investigated towards larval mortality and development of Culex pipiens L. Plant extracts exhibited variable biological activity. The greatest activity was observed for R stricta which showed LC 50s of 154.2 and 84.2 ppm, respectively after 2 and 10 days of exposure. Percentage of larval mortality was 95.33% in the treatment with extracts of R stricta and 84.8% in C. paradoxa. Egg hatchability was significantly reduced in R stricta concentrations. All concentrations of the plant extracts from R stricta, C. paradoxa (200 ppm and above) and H. bacciferum (400ppm and above) caused significantly high hindrance to the subsequent larval development and reduced both pupation and adult emergence. Drastic retardation of development was shown by R stricta extracts, where only 19.3% and 9 % of the larval managed to reach pupal and adult stages, respectively, when reared in very low concentration (100 ppm) of the extract. However, C.paradoxa and H. bacciferum were more effective at higher concentrations. Application of such plant extracts to mosquito breeding sites may have great practical importance in relation to non-synthetic chemical control of these serious disease vectors.

Summary in Arabic.

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