Frequency of resistance alleles to Lysinibacillus sphaericus in a Culex quinquefasciatus population treated with a L. sphaericus/Bti biolarvicide

This study aimed to evaluate the effect of a L. sphaericus/Bti combined biolarvicide treatment on the frequency of three cqm1 resistance alleles in Cx. quinquefasciatus larvae from one subarea (SA2) compared to another (SA1) where only L. sphaericus was kept. Larvae collected before and during a two-year trial were subjected to bioassays and PCR assays. Susceptibility to L. sphaericus showed oscillations in both areas, but no significant alterations of the lethal concentrations were detected. The pre-trial frequency of the resistance alleles was 0.057, while during the trial, the mean frequency was significantly lower in SA2 (0.068) than in SA1 (0.088). All three alleles investigated were detected in the study subareas and the cqm1REC-D19 was the most frequent allele found, regardless the treatment employed. This study showed that the use of the L. sphaericus/Bti biolarvicide was associated with a lower frequency of the resistance alleles and can be a useful tool to prevent the onset of L. sphaericus resistance.Graphical abstract

Source: Biological Control - February 11, 2019 Category: Biology Source Type: research