Detection of Bendiocarb and Carbaryl Resistance Mechanisms among German Cockroach Blattella germanica (Blattaria: Blattellidae) Collected from Tabriz Hospitals, East Azerbaijan Province, Iran in 2013.
BACKGROUND
Insecticide resistance is one of the serious problems for German cockroach control program. This study was conducted to determine the bendiocarb and Carbaryl resistance mechanisms in German cockroaches using the piperonyl butoxide (PBO).


METHODS
Bioassay tests were conducted with 4 to 6 different concentrations of both insecticides with four replicates of 10 susceptible strain cockroaches per concentration to determine of discriminative concentration. After determining discriminative concentration, the result was compared to wild strain. The levels of susceptibility and resistance ratio (RR) and synergism ratio (SR) were calculated for each five wild strains. Moreover resistance mechanisms in wild strains were determined using PBO synergist in vivo.


RESULTS
Hospital strains showed different levels of resistance to bendiocarb and carbaryl compared to susceptible strain. The bendiocarb and carbaryl resistance ratios ranged from 2.11 to 7.97 and 1.67 to 2 at LD50 levels, respectively. The synergist PBO significantly enhanced the toxicity of bendiocarb and carbaryl to all strains with different degrees of synergist ratio, 1.31, 1.39, 3.61, 1.78, 1.62 and 2.1 fold for bendiocarb, 1.19, 1.18, 1.12. 1.29, 1.45 and 1.11-fold for carbaryl, suggesting monooxygenase involvement in bendiocarb and carbaryl resistance.


CONCLUSIONS
The synergetic effect of PBO had the highest effect on bendiocarb and resistance level was significantly reduced, which indicates the important role of monoxidase enzyme in creating resistance to Bendiocarb. Piperonyl butoxide did not have a significant synergistic effect on carbaryl and did not significantly break the resistance.
College of Paramedics, Kashan University of Medical Sciences, Kashan, Iran.
Afshin
A
Salehi
Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
Hassan
H
Vatandoost
Departmemt of Parasitology, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran.
Teimour
T
Hazratian
Department of Medical Entomology and Vector Control, Faculty of Health, Hormozgan University of Medical Sciences, Bandar Abbas, Iran; Social Determinants in Health Promotion Research Center, Hormozgan University of Medical Sciences, Bandar Abbas, Iran.
Alireza
A
Sanei-Dehkordi
Department of Parasitology, School of Medicine, Kashan University of Medical Sciences, Kashan, Iran.
Hossein
H
Hooshyar
Department of Parasitology, School of Medicine, Kashan University of Medical Sciences, Kashan, Iran.
Mohsen
M
Arbabi
School of Health, Rafsanjan University of Medical Sciences, Rafsanjan, Iran.
Yaser
Y
Salim-Abadi
Research Center for Biochemistry and Nutrition in Metabolic Diseases, School of Medicine, Kashan University of Medical Sciences, Kashan, Iran.
Reza
R
Sharafati-Chaleshtori
Department of Environmental Health and Medical Entomology, School of Health, Kerman University of Medical Sciences, Kerman, Iran.
Mohammad Amin
MA
Gorouhi
Department of Parasitology, School of Medicine, Kashan University of Medical Sciences, Kashan, Iran.
Azim
A
Paksa
Bendiocarb; Carbaryl; German cockroach; Resistance mechanism