Inheritance and mechanism of resistance to Bacillus sphaericus in Culex quinquefasciatus (Diptera: Culicidae) from China and Brazil.
Investigations on the inheritance and mechanism of resistance to Bacillus sphaericus Neide in Culex quinquefasciatus Say colonies, selected with strains C3-41 (RLCq1/C3-41) and 2362 (CqRL1/2362), were performed in China and Brazil, respectively. The progeny of reciprocal F1 crosses (susceptible female x resistant male and vice versa) from both resistant colonies responded alike in bioassays, indicating recessive inheritance. Data on larvae susceptibility from the backcross offspring between F1 and their respective susceptible and resistant parental colonies are consistent with a monofactorial and autosomal mode of inheritance. In vitro binding assays between 125I binary (Bin2) toxin and the brush border membrane fractions (BBMF) from CqRL1/2362 and RLCq1/C3-41 larvae showed that resistance, in both colonies, is caused by a failure in the binding step of the B. sphaericus Bin2 toxin to its specific midgut receptor. The specific and saturable binding of Bin2 toxin to BBMF from F1 larvae (CqRL1/2362 X susceptible counterpart) confirms the recessive inheritance of the resistance gene. Further studies are needed to advance understanding of B. sphaericus resistance.
Centro de Pesquisas Aggeu Magalhães-FIOCRUZ, Departamento de Entomologia, Av. Moraes Rêgo s/n Recife-PE 50670-420, Brazil.
Cláudia M F
CM
Oliveira
Maria Helena
MH
Silva-Filha
Christina
C
Nielsen-Leroux
Guofeng
G
Pei
Zhiming
Z
Yuan
Lêda
L
Regis
D000818:Animals; D001407:Bacillus / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity*; D001427:Bacterial Toxins / Q000235:genetics; D003433:Crosses, Genetic; D003465:Culex / Q000235:genetics* / Q000276:immunology / Q000382:microbiology*; D007113:Immunity, Innate; D007814:Larva; D012098:Reproduction
D001427:Bacterial Toxins