Shahin Seidy; Mousa Tavassoli; Farnaz Malekifard
Volume 13, Issue 4 , December 2022, , Pages 529-535
Abstract
Resistance to the knockdown effect of pyrethroid insecticides occurs due to mutations at target sites of pyrethroids, meaning the voltage-gated sodium channels gene (VGSC) in the membrane of the neurons. In fleas, this mutation occurs at two sites in the sodium channel in neurons: one is the replacement ...
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Resistance to the knockdown effect of pyrethroid insecticides occurs due to mutations at target sites of pyrethroids, meaning the voltage-gated sodium channels gene (VGSC) in the membrane of the neurons. In fleas, this mutation occurs at two sites in the sodium channel in neurons: one is the replacement of leucine with phenylalanine (L1014F) and the other is the replacement of threonine with valine (T929V). In this study, 81 Pulex irritans and 47 Ctenocephalides canis fleas were collected from five provinces in the west and northwest of Iran. Adult fleas were exposed to cypermethrin 0.75%, and the mortality rate was calculated after 1 and 8 hr, and the mutation sites in the VGSC gene were investigated. The lethality of cypermethrin 0.75% for P. irritans was 40.00 - 57.14% after 1 hr and 60.00 - 73.91% after 8 hr. The lethality of this dose for C. canis after 1 and 8 hr of exposure was 33.33 - 41.17% and 66.66 - 80.33%, respectively. The VGSC sequence analysis indicated two mutation sites in the resistant and one mutation site in the susceptible fleas. The VGSC sequence analysis of susceptible P. irritans showed that 5.50% of them were homozygous susceptible and 94.45% were hetero-zygous susceptible. Susceptible C. canis were 5.26% homozygous and 94.73% heterozygous susceptible. All the resistant fleas were homozygous. The development of pyrethroid resistance and high-frequency L1014F mutation in fleas suggest that pyrethroids are likely to be ineffective in controlling fleas. Therefore, monitoring pyrethroid resistance and its underlying mechanisms are necessary for controlling fleas and finding new alternative control methods.
Awat Samiei; Mousa Tavassoli; Karim Mardani
Volume 11, Issue 3 , September 2020, , Pages 243-248
Abstract
The present study was aimed to assess the bedbugs susceptibility to pyrethroid insecticides using molecular analysis. With the aid of pest control companies, adult bedbugs were collected from various places such as hotels, residential houses, and industrial buildings in seven cities highly crowded with ...
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The present study was aimed to assess the bedbugs susceptibility to pyrethroid insecticides using molecular analysis. With the aid of pest control companies, adult bedbugs were collected from various places such as hotels, residential houses, and industrial buildings in seven cities highly crowded with domestic and foreign tourists in Iran from May 2016 to August 2017. Bedbugs were colonized in the laboratory to evaluate their resistance to pyrethroid using insecticide resistance bioassay. Genomic DNA was extracted from susceptible and resistant bedbugs. At first, specie specific primers targeting cytochrome oxidase subunit I (COI) gene was performed to confirm Cimex hemipterus species. Then, kdr-like gene was examined for point mutation using PCR and nucleotide sequencing. Bioassay showed that 11 out of 35 examined bedbugs were resistant to pyrethroids (31.43%; 95.00% confidence interval: 29.48-33.08%). The DNA sequencing showed that all examined bedbugs collected from Tehran province had homozygous V419L kdr-like gene mutations. The level of pyrethroid resistance found in the collected bugs from Tehran province indicated that this phenomenon has already been prevailed in the site and prompts the need to reevaluate the large use of pyrethroids to control the bedbugs.
