Susceptibility of Different Strains of the Sunn Pest, Eurygaster integriceps Put. and Eurygaster maura L. (Heteroptera: Scutelleridae) to Fenitrothion and Alpha-cypermethrin in Turkey
The Sunn pest are a group of insects representing several genera of the shield bug (Scutelleridae) families, including the species Eurygaster integriceps Put. and Eurygaster maura L. (Hemiptera: Scutellaridae) being the most economically important pests in Middle Anatolia, Southeast Anatolia and Thrace in Turkey. Chemical control has been the main method used against these pests. Chlorinated hydrocarbon, organophosphorus and pyrethroid insecticides have been used since 1955. The aim of this study was to determine the resistance levels of sunn pest, Eurygaster spp. collected from wheat fields in different regions of Turkey to alpha-cypermethrin and fenitrothion. Insecticide toxicity was measured using a topical bioassay method using new generation adults. Insects were treated on the pronotum with one microlitre aliquots of insecticide in acetone for treatments and acetone alone for the control. After treatment, insects were maintained at laboratory conditions and mortality was recorded after 48 hours. Results were analysed and LD50 values were determined by using probit analysis. The results of bioassays showed that there was no resistance in E. integriceps Put. strains to alpha-cypermethrin and fenitrothion. The resistance ratio for alpha-cypermethrin were determined 1.7 and 1.9 fold in the Diyarbakır and Tekirdağ strains of E. integriceps Put., respectively. For fenitrothion, the resitance ratios were determined 2.3 and 1.4 fold in the Diyarbakır and Şanlıurfa strains, respectively. In Eurygaster maura (L) strains, resistance ratios varied from 3.3 to 7.6 for alpha-cypermethrin and 1.05 to 1.9 for fenitrothion. The results obtained showed that there was no resistance in E. integriceps Put. strains to alpha-cypermethrin and fenitrothion. However, Yozgat, Kırıkkale and Konya strains of E.maura from Middle Anatolia had some resistance development to alpha cypermethrin but there was no evidence of resistance development to fenitrothion.
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