Assessment of some chemical and biorational insecticides against culex pipiens (Diptera : Culicidae)‎ in Abha City, Saudi Arabia

الملخص EN

The present study was tested certain chemical insecticides (Propetamphos and Cypermethrin) and a Bioinsecticide (Baciloid 5000: Bacillus thuringiensis) against Culex pippins, the dominant mosquito species in Abha City.

LC50 value of Propetamphos was 0.0162 ppm against the 3rd instar larvae of laboratory strain compared with field strain which was 0.0442 ppm, and LC90 of Propetamphos was 0.8109 ppm against the 3rd instar larvae of laboratory strain, comparing to field strain (3.31ppm).

Cypermethrin was also very effective where LC50 was 0.0132 ppm against the adult females of laboratory strain, comparing to (0.1192 ppm) of laboratory strain.

On the other hand, residual activity of Bacillus thuringiensis var.

israelensis reached from 4 to 20 days of concentrations ranged between 0.001 to 100 ppm (lethality was 11.7 to 96.8%) in laboratory strain in the 1st week, whereas ranged between 0.0 to 70.8% in the 2nd week with same concentrations finally ranged between 0.0 to 12.7% in the 3rd week.

While reached 6 -23 days at concentrations 0.001 to 100ppm in field strain in the 1st week, whereas ranged between 0.0 to 70.8% in the 2nd week with the same concentrations and ranged between 0.0 to 12.7% in the 3rd week.

So, the field collected larvae of Cx.

pipens were more susceptible and have prolonged residual effect as compared to laboratory reared larvae.