ABSTRACT
This study was conducted to monitor the housefly "Musca domestica" population abundance in different districts of Alexandria Governorate throughout one year from January to December 2002. Also, it determined the susceptibility of housefly against different currently used insecticides by Ministry of Health and Population [namely malathion and azamethiphos against adults and chlorpyriphos against larvae]. In addition, it evaluated the effect of a botanical compound; neem oil against both adults and larvae as an alternative insecticide. The data demonstrated that the highest housefly abundance was observed in El-Amreya and West Districts with mean grid count of 75.0 +/- 40.8 and 72.9 +/- 46.3, respectively. The lowest housefly abundance was observed in Borg El-Arab and East Districts with mean grid count of 37.7 +/- 19.7 and 39.5 +/- 28.1, respectively. The order of housefly population abundance in different districts of Alexandria Governorate was as follows: El-Amreya > West > El-Montaza > Middle > El-Gomrok> East> Borg El-Arab. Also, the abundance of housefly was greatly affected by temperature fluctuation where there were two peaks observed in Spring and Autumn while there were two depressions in Summer and Winter. There was a negative significant correlation between housefly abundance and both shadow and wind. As regards the susceptibility of housefly towards tested insecticides, the LD[50] of malathion against adult insect using topical application for laboratory strain was 0.0199 mg/fly while in case of field strain, it was 0.0363 mg/fly [1.824 times more than that of laboratory strain]. As regards azamethiphos using diet treatment, the LC50 for laboratory strain was 0.0281% while it was 0.0312% for field strain [1.11 times more than that of laboratory strain]. The EC50 of chloropyriphos using diet treatment against first instar larvae of field strain of housefly was 3.50 ppm. The most prominent toxic effect of neem oil emulsion was noticed in larval stage where EC[50] for laboratory strain was 1982.9 ppm, while it was 2045.3 ppm for field strain. Neem oil had no toxic effect on adult housefly by either topical application or diet treatment. In conclusion, the study reports no resistance of housefly against the tested compounds