Susceptibility Status of Several Field-Collected German  Cockroaches (Blattella germanica) to a Pyrethroid Insecticide and Molecular Detection of Knockdown Resistance (kdr)

Kamal  Dashti; Saber  Gholizadeh; Morteza Zaim; Mozhgan  Baniardalani; Hamidreza  Basseri

doi:10.18502/ijph.v53i4.15573

Kamal Dashti Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences , Tehran, Iran
Saber Gholizadeh Department of Medical Entomology and Vector Control, School of Health, Urmia University of Medical Sciences, Tehran, Iran
Morteza Zaim Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences , Tehran, Iran
Mozhgan Baniardalani Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences , Tehran, Iran
Hamidreza Basseri Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences , Tehran, Iran

DOI: https://doi.org/10.18502/ijph.v53i4.15573

Keywords: German cockroach; Field strains; Insecticide resistance; Heterogeneity

Abstract

Background: High frequency of insecticide used to control German cockroaches may lead to insecticide resistance development. We aimed to compare the level of insecticide resistance and heterogeneity in insecticide resistance of field-collected German cockroaches in eight selected zones of Mashhad City, Razavi Khorasan Province, Iran.

Methods: The present study was conducted from October 2019 to May 2021. Adult and nymphs of German cockroaches were collected from infested restaurants or hotels in eight zones of Mashhad City and then colonized in an insectarium. The cockroaches were subjected to bioassay against cypermethrin insecticide. In addition, the genomic DNA of each cockroach population was analyzed in the region where the kdr mutations reside in the German cockroach.

Results: The LT₅₀ values against cypermethrin in the susceptible strain (SS) and eight field-collected strains so varied from 17.52 to 95.36 min. The resistance ratio of the strains was also different in response to the insecticide. The similarity of multiple sequence alignments at the amino acid level was 97.5%-100%. An exon 20 transversion mutation and a nonsynonymous substitution were found. The L1014F substitution was detected in 83.4% of the cockroach samples.

Conclusion: The field-collected strains were resistant to cypermethrin at different levels. Furthermore, the molecular study confirms the heterogeneity in the level of resistance among eight strains. Therefore, eight strains might have a different history of insecticide treatment.