The photosensitizing activity of different photosensitizers irradiated with sunlight against aquatic larvae of Culex pipiens L. (Diptera: Culicidae)

Abstract

The response of Culex pipiens early 3rd instar larvae to three photosensitizing dyes (Toluidine blue O, Methylene blue, and Rose Bengal) was studied under laboratory conditions. Despite lack of toxicity in dark and with exposure to only sunlight, C. pipiens third instar larvae were highly sensitive to the three tested photosensitisers with 20 minutes of sunlight irradiation. Larvae showed the most sensitivity to Rose Bengal (RB) with LC50 values of 1.07, 1.19, 1.35, 1.65µM, and LC90 values of 3.88, 3.98, 4.19, and 4.51µM. Also, less sensitivity to methylene blue (MB) was recorded with LC50 values of 2.70, 2.79, 2.99, 3.08µM and LC90 values of 4.82, 4.90, 5.04, and 5.22µM. In addition, the least sensitivity was recorded by larvae towards toluidine blue o (TBO) with LC50 values of 3.30, 3.39, 3.58, and 3.87µM and LC90 values of 5.23, 5.32, 5.57, and 5.96 µM, respectively. Results showed that photosensitizers could be an excellent replacement for the traditional insecticides avoiding their negative impact on the environment.