title: Potential for Culex pipiens to develop resistance against Bacillus sphaericus toxins.
abstract: Susceptibility of field Culex pipiens populations to Bacillus sphaericus and the possibility of resistance development in the selected laboratory colony were investigated. 180 populations collected from Giza and Qualyobia over one year show no marked variation at LC50 and LC90 values. Larvae of laboratory colony of Cx pipiens were subjected to selection pressure with a preparation of Bacillus sphaericus strain 2362 at LC80 values for 20 successive generations. The selected laboratory colony began developing resistance at F10 (RR = 1.69) when compared with its unselected counterpart. The magnitude of resistance increased gradually and reached 33 fold by F20. The unselected colony reared without any exposure to the B. sphaericus toxin, did not show any marked change in their susceptibility to this microbial agent.
authors.affiliation: Department of Biological Science, Faculty of Education, Suez Canal University, Suez, Egypt.
authors.forename: B A
authors.initials: BA
authors.lastname: Soliman
authors.forename: M K
authors.initials: MK
authors.lastname: Tewfick
authors.forename: G A
authors.initials: GA
authors.lastname: Hafez
mesh_terms: D000818:Animals; D001407:Bacillus; D001427:Bacterial Toxins / Q000494:pharmacology*; D003465:Culex / Q000187:drug effects / Q000276:immunology / Q000382:microbiology*; D007113:Immunity, Innate; D012641:Selection, Genetic
chemical_list: D001427:Bacterial Toxins