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Investigation of the role of glutathione S-transferase isozymes in pyrethroid resistance of Helicoverpa armigera in Turkey

Konus, Metin
Ugurlu, Sakine
İşcan, Mesude
Helicoverpa armigera, cotton bollworm, is one of the insects causing severe yield loss of economically important crops including cotton, legumes and vegetables. It has developed resistance against the pyrethroid insecticides that have been introduced into market. Resistance against pyrethroids have been reported in H. armigera populations at various parts of the world, however, except 1-chloro-2,4-dinitrobenzene substrate (CDNB), almost no any other substrates used for analysis of the role of glutathione S-transferases (GST) in pyrethroid resistance of H. armigera. In this study, in addition to CDNB, GST activities were determined using 4-nitrobenzylchloride (PNBC), 3,4-dichloronitrobenzene (DCNB) and 1,2-epoxy-3-(p-nitrophenoxy)propane (EPNP) as substrates. Midguts of H. armigera obtained from Çanakkale (n = 30) and Mardin (n = 30) field populations and a susceptible (n = 30) population obtained from Germany. GST-PNBC activities in Çanakkale and Mardin field populations showed statistically significant (p < 0.05), 2.2- and 4.8-fold increase, respectively, compared to susceptible population. Similarly, GST-DCNB activities showed statistically significant (p < 0.05), 2.0- and 4.8-fold increase in Çanakkale and Mardin field populations, respectively. However, as GST activities of both populations were determined using common substrate CDNB, only Mardin field population showed statistically significant (p < 0.05), 1.5-fold increase compared to susceptible population, no change in the GST-CDNB activity was observed in Çanakkale field population. Finally, GST activities against EPNP in Çanakkale and Mardin field populations were not detected. Thus, it may be concluded that GST isozymes using DCNB and PNBC as substrates play a role in pyrethroid resistance of Çanakkale and Mardin field populations.