Detection of organophosphate and pyrethroid resistance alleles in Czech Leptinotarsa decemlineata (Coleoptera: Chrysomelidae) populations by molecular methods.

Background: Pyrethroids and organophosphates are the most frequently used insecticides for Colorado potato beetle, Leptinotarsa decemlineata (Say), control in the Czech Republic. Based on molecular methods, organophosphate and pyrethroid resistance alleles have been detected in samples from three sites. The accuracy of restriction fragment length polymorphism (RFLP) and bidirectional polymerase chain reaction amplification of specific alleles (Bi-PASA) for detection of resistance alleles is compared.

Results: Leptinotarsa decemlineata from three sites showed higher frequencies of resistance alleles to organophosphates than to pyrethroids. The rates of occurrence of individuals homozygous resistant (RR) to pyrethroids ranged from 20.0 to 22.9%, while the rates of occurrence of individuals RR to organophosphates ranged from 52.9 to 66.7%. The incidences of individuals with resistance alleles to both organophosphates and pyrethroids ranged from 8.6 to 13.6%. No relationship was found between incidence of the pyrethroid resistance allele and site, while incidence of the organophosphate resistance allele differed significantly according to site.

Conclusion: Both RFLP and Bi-PASA were suitable for detecting resistance alleles to pyrethroids, and in most cases also for detecting resistance alleles to organophosphates. In contrast to Bi-PASA, RFLP was also suitable for samples with lower DNA quality when testing for the resistance allele to pyrethroids. On the other hand, RFLP was not as accurate as Bi-PASA in detection of the organophosphate resistance allele.