Pamuk yaprak kurdu Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae)'te insektisitlere karşı oluşan direncin biyokimyasal ve moleküler karakterizasyonu
Özet
This study was performed in the aim of identifying the biochemical and molecular mechanisms of resistance to organophosphates (chlorpyrifos), carbamates (carbamate) and synthetic pyrethroids (deltamethrin) observed in S. littoralis populations collected from Adana, Mersin, Egypt and Israel and have been maintained in the laboratory.The response of Adana, Mersin, Egypt and Israel populations to chlorpyrifos, carbamate and deltamethrin was identified. The populations were all insensitive to even the highest dose of carbamate. The most susceptible and the most resistant populations to chlorpyrifos are Adana and İsrail, respectively. The most susceptible and the most resistant populations to deltamethrin are Mersin and Egypt populations, respectively. Since the resistance mechanisms developed by S. littoralis to pyrethroids have not been identified clearly yet and especially since there are not any studies concerning molecular characterization of those mechanisms, this study have continued in this direction. Part of the Israel population was subjected once a generation to deltamethrin dose that kills about 90 % of the former generation in order to increase deltamethrin resistance. This has done for 6 generations, and the resistance ratio was 17,10 at generation F6. The activities of esterase, cytochrome P450 monooxygenase and glutathione S-transferase were found to increase as the resistance increases. The esterase bands on native-PAGE were observed as darker and thicker for resistant individuals. The synergistic ratios were found to be 8,5 by PBO and 6,3 by DEM when the populations were exposed to deltamethrin. Reciprocal crosses have been carried out and the inheritance of deltamethrin resistance was found to be controlled by an autosomal and codominant trait.The cDNAs of IIS4-IIS6 region of voltage-gated sodium channel gene of both deltamethrin susceptible and resistant (F6) populations were cloned, sequenced and aligned with each other as well as other related species. Any mutation related to resistance could be detected, except for a point mutation that gives rise to substitution of serine instead of asparagine at position 927. The deltamethrin resistance observed in S. littoralis, is thought to be the result of metabolic detoxification where the induced activities of monooxygenases, esterases and GSTs observed.The use of insecticides with different modes of action and thus relaxation pyrethroid selection pressure for some periods, allowing gene flow to dilute the resistance allels in field conditions, avoidance of pyrethroid use on crops other than major cash crops are some of the recommendations for efficient resistance management strategies for S. littoralis.On the other hand, the sequence of a region of sodium channel of Spodoptera littoralis has been identified for the first time in this study.