Study of the Seasonal Activity and Dynamic Fluctuation of Medically Important Species of Mosquitoes with Reference to Testing the Susceptibility of the Dominant Species Culex pipiens L. 1758 to some Insecticides in Jeddah

The work was carried out for two years from January 2008 up to December 2009. During the survey, 30907 adult mosquitoes were collected representing 9 different mosquito species. These species were belonged to the genera of Aedes, Culex and Anopheles. Moreover, A survey of larval stages of mosquitoes from 87 different breeding sites in Jeddah governorate was conducted. The records showed that Cx. pipiens mosquito larvae were the dominant species. On the other hand, the technique of Polymerase chain reaction (PCR) was used to detect the virus of dengue fever in mosquito females of Ae. aegypti and Ae. caspius. The results indicated that all samples tested for virus of dengue were found negative (-) except one sample of Ae. aegypti which was positive (+). Susceptibility levels of Cx. pipiens mosquito larvae treatment with some conventional and non-conventional insecticides were determind. Mosquito larvae of Cx. pipiens proved to be more susceptible to the pyrethroid Pesgard than the organophosphate Actikil and the bacterial insecticide Bacilod, respectively. On the other hand, the records showed that treatments with the chitin synthesis inhibitor dudim and the plant extract neem oil against mosquito larvae of Cx. pipiens produced different biological effects similar to those induced by other IGRs. The joint action of different mixtures against mosquito larvae was expressed as the co- effective factor (C.F.). Values of C.F. showed that the joint action of Bacilod with Actikil and Pesgard produced different levels of potentiation and additive effects in respect. The same trend of additive effects was obtained when the plant extract neem oil applied jointly with dudim respectively. The effectiveness of slow- release formulations (SRFs) of two Insect growth regulators (IGRs) Altosid XR-briquets and Dudim tablets against mosquito larvae of Culex pipiens was evaluatd. The effective control of the present SRFs was defined as 90-100% inhibition of adult emergence.The result showed that the treatment with Altosid XR-briquets and Dudim tablets against mosquito larvae gave effective control with 90-100% inhibition of adult emergence for 67، 86 days and 37، 62 days, in tap water and pond water respectively. The susceptibility status of a field mosquito strain of Cx pipiens females against three pyrethroid insecticides and two organophsphorous insecticides was determined. The insecticides were tested at diagnostic dosages using WHO impregrated filter paper assays. The records showed that exposure of mosquito adult females to the diagnostic dosages of permethrin (0.75) , lambdacyhalothrin (0.5%) , cyfluthrin (0.15%), Malathion (5%) and Fenitrothion (1.0%) caused 57 , 48, 58, 41 and 23% mortality, respectively, indicating resistance of the present mosquito species Cx. pipiens to the tested adulticides.