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Roles of detoxification enzymes in pyrethroid resistance of Helicoverpa armigera from Turkey

Konus, Metin
UgurIci, Sakine
İşcan, Mesude
Abstracts / Toxicology Letters 180S (2008) S32–S246S169Helicoverpa armigera, cotton bollworm, is a polyphagous insect. Itis one of the most important preharvest pests for economicallyimportant crops including cotton, legumes, and vegetables.In this study, midguts ofH. armigeraobtained from Adana,Antalya, C ̧ anakkale and Mardin field populations were used. GSTactivities were determined using 1-chloro-2,4-dinitrobenzene asa substrate. Adana and Antalya field populations showed statisti-cally significant (p< 0.05), 2.4 and 2.9 fold increase, respectively,compared to susceptible population. General esterase activitymeasurements were done with Adana, Antalya and susceptiblepopulations by usingp-nitro phenyl acetate as a substrate. Adanapopulation showed statistically significant increase (p< 0.05); nev-ertheless, a small increment (1.29 fold) was found as compared tosusceptible population. Although, Antalya population did not showstatistically significant increase (p> 0.05) compared to susceptiblepopulation, it exhibited tendency to increase.The role of cytochrome P-450 monooxygenases (CYP6B6,CYP6B7, and CYP9A12) in pyrethroid resistance developmentanalyzed using Reverse Transcriptase-PCR method. In these exper-iments, C ̧ anakkale and Mardin field populations ofH. armigerawere used. Some individuals in both field populations exhibitedslight increases in gene expressions of CYP6B7 and CYP9A12 genescompared to susceptible individuals. CYP6B6 gene expressionwas not detected in susceptible strain; nonetheless, expressionof the same gene was observed in some of the individuals fromMardin and C ̧ anakkale field populations. Increased GST activity inconjunction with activation of CYP6B6 appears to play a role in theresistance of TurkishH. armigerain monitored field