No abstract

No abstract

Tomato is one of the most important vegetable crops in Turkey, with national production of over 10 million tonnes in 2010. Tuta absoluta (Meyrick) is an important pest of tomato, and was first recorded in Urla District of Izmir Province in the Aegean region of Turkey in August 2009. It has since spread rapidly to the other regions of Turkey and become the main pest of tomato. Since its dispersal, chemical control has been the main method of control. Intensive use of insecticides has led to the development of resistance in T. absoluta. In this study, the baseline toxicity (LC50 values) of some insecticides was determined using a leaf‐dip bioassay method in Antalya and Ankara populations of T. absoluta.

No abstract

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 Kırıkkale 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 Kırıkkale population (3.0-fold), EST-PNPA activities showed an increase only in Samsun population (1.3-fold). Finally, GST-CDNB activities increased both in Kırıkkale (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 Kırıkkale population of S. zeamais from Turkey.