Browsing by Author "Karaagac, Sakine Ugurlu"

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Analysis of Molecular Resistance Mechanisms in Helicoverpa Armigera (Hubner) (Noctuidae: Lepidoptera) Populations Under Pyrethroid Stress in Turkey
(Gazi Entomological Research Soc, 2014) Konus, Metin; Karaagac, Sakine Ugurlu; Iscan, Mesude
Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) is a major pest of economically important crops such as cotton, tomato and soybean. In order to control this pest, pyrethroid insecticides have been extensively used in farming areas all over the world. However, applications of excessive amounts of these insecticides can result in resistance development in the field populations of H. armigera. Resistance to the pyrethroids, beta-cypermethrin and lambda cyhalothrin, was analysed using bioassays. It was found that a canakkale field population of H. armigera field showed low (2.1-fold) and moderate (14.5-fold) resistance levels for beta-cypermethrin and lambda-cyhalothrin, respectively. Furthermore, expressions of selected CYP450, GST and esterase genes of H. armigera canakkale field populations were compared to those of a susceptible strain using real-time PCR. Our results indicate that H. armigera reacts to pyrethroids mainly by increasing expression levels of CYP450s such as CYP9Al2 and CYP9A14. However, GST and esterase genes expression levels were not significantly altered in a field population. GSTs and esterases were also analyzed using biochemical assays. While GSTs and esterase genes were not found to be up-regulated in the real-time PCR, except GST-DCNB activity, the biochemical assays also showed no significant increases in enzyme activities in the canakkale field population as compared to the susceptible strain. Consequently, CYP9Al2 and CYP9A14 together with certain GSTs, catalyzing DCNB substrate, are proposed to be involved in the metabolic responses against beta-cypermethrin and lambda-cyhalothrin insecticides in field population of H. armigera from Turkey.
Determination of Organophosphate Resistance Status and Mechanism in Sitophilus Zeamais Motschulsky (Coleoptera: Curculionidae) From Turkey
(Walter de Gruyter Gmbh, 2015) Karaagac, Sakine Ugurlu; Konus, Metin
Objective: The objectives of this study were to determine resistance status to malathion and pirimiphos-methyl insecticides and to make biochemical analysis of resistance mechanism(s) developed to these insecticides in Sitophilus zeamais (S. zeamais) populations, collected from two different locations in Turkey. Two organophosphate insecticides, malathion and pirimiphos-methyl, were examined by bioassay using a discriminating dosage technique with impregnated filter papers. Mortality percentages were determined at the discriminating doses of these insecticides. In addition, esterase, glutathione S-transferase, and cytochrome P450 monooxygenase activities were also determined in this study in order to analyze detoxification mechanism(s) of tested insecticides in S. zeamais. Methods: Bioassay experiments of malathion and pirimiphos-methyl insecticides in S. zeamais populations were performed according to the IRAC susceptibility test method No:006. Furthermore, enzyme activities of esterases, cytochrome P450 monooxygenases, and glutathione S-transferases were determined by using biochemical assays. Results: The bioassay results of malathion and pirimiphos-methyl showed that only Kirikkale population of S. zeamais has resistance to both malathion and pirimiphos-methyl insecticides. However, no resistance was detected to malathion and pirimiphos-methyl insecticides in Samsun population of S. zeamais. Additionally, biochemical analysis displayed that while CYP450-PNOD activities showed an increase only in Kirikkale population (3.0-fold), EST-PNPA activities showed an increase only in Samsun population (1.3-fold). Finally, GST-CDNB activities increased both in Kirikkale (1.4-fold) and Samsun (2.2-fold) populations of S. zeamais compared to susceptible population. Conclusion: Consequently, cytochrome P450 monooxygenases and glutathione S-transferases seem to play a role in organophosphate resistance in Kirikkale population of S. zeamais from Turkey.
Determination of Possible Detoxification Mechanisms of Insecticide Resistance in Tribolium Castaneum (Herbst) Populations From Turkey
(Parlar Scientific Publications (p S P), 2016) Karaagac, Sakine Ugurlu; Konus, Metin
Red flour beetle, Tribolium castaneum (Herbst), is one of important grain storage pests in the world. The pest contributes to maximum spoilage of the stored grains at larval and adult stages. Infestation by these beetles results in an unappealing smell due to the secretion of benzoquinones from abdominal glands. In order to protect the stored product from this pest loss, insecticides are commonly used all over the world including Turkey. As a consequence of repeated chemical treatments, many cases of insecticide resistance have been detected in the genus Tribolium around the world. In order to estimate resistance status of T. castaneum to organophosphate insecticides, impregnated filter paper bioassay method was used. It is important to know resistance status of insecticides for resistance management. Hence, resistance status of T. castaneum to malathion, pirimiphos-methyl, and chlorpyriphos methyl insecticides was determined. In addition, detoxification mechanism was analysed by determining glutathione S-transferase and esterase activities with biochemical assays. The objective of this study was to examine the susceptibility in two populations of T. castaneum from Turkey to different contact insecticides and to analyse possible role(s) of glutathione S-transferases and esterases in detoxification mechanism in tested populations
Real-Time Pcr Analysis of Pyrethroid Resistance in Helicoverpa Armigera From Turkey
(Turkish Biochem Soc, 2014) Konus, Metin; Karaagac, Sakine Ugurlu; Iscan, Mesude
Aim: Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) is a polyphagous pest of a wide range of crops such as cotton, tomato and soybean. Pyrethroid insecticides have commonly used against it in agricultural areas, but excess amount applications of them result in resistance development in the field populations of H. armigera. Resistance development usually occurs with increased metabolism of certain enzymatic systems such as CYP450, GST and esterases. Therefore, expressions of selected CYP450, GST and esterase genes of H. armigera field populations (Adana and Mardin) were compared to those of a susceptible strain by real-time PCR method for analyzing role of these systems in pyrethroid resistance development of H. armigera. Material and Methods: Real-Time PCR Method Results: It was found that H. armigera reacts to pyrethroids mainly by increasing expressions of CYP9A14 gene together with CYP4S1 and CYP9A12 genes. However, analyzed GST and esterase genes expression were not significantly changed in field populations. Conclusion: Consequently, while CYP450 enzyme system is actively involved in pyrethroid resistance, GSTs and esterases enzyme systems don't seem to be actively involved in resistance development against pyrethroid insecticides in H. armigera field populations from Turkey.