Journal of Medical Entomology (2002) 39, 729-735
Christina Nielsen-Leroux, Nicole Pasteur, Jérôme Prètre, Jean-François Charles, Hassen Ben Sheikh and Christine Chevillon (2002)
High resistance to Bacillus sphaericus binary toxin in Culex pipiens (Diptera: Culicidae): The complex situation of west Mediterranean countries
Journal of Medical Entomology 39 (5), 729-735
Abstract: This study was aimed at clarifying the nature of the resistance to Bacillus sphaericus Neide (Bs) that Culex pipiens L. has developed in west Mediterranean countries, France, and Tunisia. Two recessive and sex-linked mutants, sp-1R and sp-2R, were previously detected in southern France. Here, the Tunisian resistance was also shown to involve a single recessive and sex-linked gene that was temporarily named sp-TR. In addition, sp-1R, sp-2R, and sp-TR were shown to separately confer a similar high resistance level (>5,000-fold) in the homozygous state. Knowing that sp-1R resistance does not alter the binding of Bs binary toxin to its specific receptor, we investigated this character in sp-2RR and sp-TRR homozygotes. This was performed by in vitro experiments in which larval brush border membrane fractions (BBMF) were exposed to the 125I-Bin2 toxin of B. sphaericus strain 1593. The toxin-receptor binding was found disrupted by sp-2R but not by sp-TR. Comparing the binding kinetics among nine Culex pipiens strains of diverse origins revealed that the Bs receptors of sp-1RR and sp-TRR homozygous larvae were displaying the highest affinity toward Bs binary toxins. These results are discussed with regard to alternative assumptions on the dynamics of high Bs-resistance and on the emerging possibilities to test them in a near future.
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Database assignments for author(s): Christina Nielsen-Leroux
Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
pesticide resistance of pest
Research topic(s) for beneficials or antagonists:
resistance/tolerance/defence of host
Pest and/or beneficial records:
Beneficial | Pest/Disease/Weed | Crop/Product | Country | Quarant.
|
---|---|---|---|---|
Culex pipiens | France | |||
Culex pipiens | Tunisia | |||
Lysinibacillus sphaericus (entomopathogen) | Culex pipiens | France | ||
Lysinibacillus sphaericus (entomopathogen) | Culex pipiens | Tunisia |