Background: The common house mosquito, Culex pipiens, is
abundant in Egypt and act as a vector of pathogens of medical and
veterinary importance. Aim: The present study aimed to compare
the toxic effect of rose bengal a photosensitizer to that of
chlorpyrifos, a commercially available larvicide against the early 3rd
larval instar of Cx. pipiens. Methods: We compare the toxic effect
of rose Bengal exposed to sunlight from 10 am to 4 pm to that of
chlorpyrifos, against the early 3rd larval instar of Cx. pipiens.
Results: Treatments revealed dose-dependent mortality, reaching
100% after treatment with rose bengal for 6 hrs and 90.6% for
chlorpyrifos for 24 hrs. Six hours post-treatments, the LC50 of rose
bengal and chlorpyrifos were 4.9x10-6 and 4.9x10-4, respectively;
while the LC95 were 2.0x10-3 and 4.0x0-3, respectively. Based on the
LC50 values of chlorpyrifos as a reference substance, rose bengal
was found 100 times more potent than chlorpyrifos. The LT50 of
rose bengal ranged from 34.8 to 1.1 hrs post-treatment with1×10-6 M
and 1×10-2, respectively. The LT50 values of chlorpyrifos ranged
from 3065.9 to 6.1 hrs after subjecting to 1×10-4 M and 1×10-3,
respectively. Conclusion: It could be concluded that rose bengal
could be used to prevent mosquito bites and their associated diseases
as an alternative to traditional insecticides and an eco-friendly
larvicide. |
