Comparative inhibitory action of 4 standard bacteriophages on the larvicidal activity of certain mosquito pathogenic bacteria against culex pipiens larvae

Four bacteriophages [CP-51, CP-54, Yousten-4 and Yousten-14] were assayed against 7 entemopathogenic bacterial strains. The two CP ones, indicating variability of the host range of the tested phages was suggested to be related to the environmental characteristics of the tested strains. On testing the susceptibility of 5 bacterial strains to the phage Yousten-4 at different cultural ages, a correlation was found between incubation time and level of bacterial susceptibility to the tested phage. This observation was explained to be due to the number of vegetative cells and/or sporulation

field survey of bacteriophage contamination of mosquito breeding places, inhibiting bacterial insecticide

Twelve geographically different mosquito breeding places were described and sampled for the detection of naturally existed bacteriophage viruses which could transduct and lysate 5 entomopathogenic bacteria. The surveyed places are classified into seepage, sewage, and irrigation breeding water. Bacterial free filtrates of the collected samples were assayed against the tested bacteria in vitro and against 3rd instar Culex pipiens larvae as well. Nine out of the twelve places could demonstrate the presence of phages. Bacillus thuringiensis H-14 was found susceptible to phage[s] present in polluted and irrigated water of 5 locations, while B. thuringiensis Berliner was susceptible to only a specific phage of one breeding place [pollutes, sewage water]. With regard to Bacillus sphaericus strains 1593 and 114, bacteriophages of sewage and irrigated water could lysate them and these phages are characterized by being of a moderate host range, except one phage which showed high specificity with strain 114 and was detected in a polluted sewage water sample collected from Daqahlia Governorate. The detected phages proved to lysate both B. thuringiensis H-14 and B. sphaericus 1593 on their larvicidal action through a series of bioassay experiment, almost all results indicate the presence of a significant inhibitory activity

Isolation, purification and ultrastructure of bacteriophages from natural mosquito breeding places in Egypt

Two bacteriophages were isolated from field collected samples representing two different mosquito breeding places. The phage AB-1 [isolated from Abheit Village, Fayoum Governorate "seepage water"] and the phage GA-2 [isolated from El-Gabal El-Asfer, Qalyoubia Governorate "sewage drain water"] were purified. Both bacteriophages were ultrastructurally described with respect to their morphology, dimensions, phases of bacterial attack and lysogeny. No major differences were observed between both isolated phages in relation to specificity, however, they were isolated from two different types of breeding places and two different geographic areas as well. This study may assume a wide host range of the isolated phages and reflect how bacterial insecticides used for mosquito larval control could be inhibited by such bacteriophage

Antibacteriophage action on the larvicidal activity of bacillus thuringiensis H-14 and bacillus sphaericus against culex pipiens

An organically polluted mosquito breeding water was tested for the presence of bacteriophages which could inhibit the larvicidal activity of B. thuringiensis H-14 and B sphaericus. More than one bacteriophage were isolated which could inhibit the tested bacteria. The sensitivity of the two bacterial species to 12 antibiotics was tested. Two of them, showed no antibacterial action, were selected and considered as antivirus agents in the bacteriophage assays; namely, Amoxycillin and Co-Trimoxazole. Results indicated their antivirus activity as the addition of the antibiotics to the isolated phages could permit normal bacterial growth as well as persistence of larvicidal activity against Culex pipiens larvae