Development of Resistance in European Red Mite Panonychus ulmi (Koch.) to Commonly Used Pesticides in Kashmir.

Dose mortality response in adults of European red mite Panonychus ulmi (Koch) to various pesticides, viz., fenazaquin, dimethoate, endosulfan, chlorpyrifos and ethion and development of resistance populations to recurrent application of fenazaquin were studied in the Division of Entomology, SKUAST-K, Shalimar during the year 2007 and 2008, and genetic variation analyzed by randomly amplified polymorphic DNA polymerase chain reaction (RAPD-PCR) technique of the selected populations were carried out at the Insect Molecular Biology Laboratory, Department of Entomology, PAU Ludhiana (Pb). The findings of the investigation revealed that P. ulmi at different locations in Kashmir valley responded differently to different pesticides used. For fenazaquin the highest LC50 values of 0.0041 per cent and resistance factor of 6.54 were recorded in Mattan (District Anantnag) while as the lowest LC50 value of 0.0010 and resistance factor of 1.60 was recorded in Merihama (District Anantnag) and Rajpura (District Shopian) respectively. The LC50 value of the susceptible population was worked out to be 0.0006277 per cent. In case of dimethoate the highest LC50 value of 0.029 per cent and resistance factor of 11.47 were observed in Kunil (District Kupwara) while the lowest LC50 value of 0.014 per cent and resistance factor of 5.54 were observed in Wagoora (District Baramulla) and Kellam (District Shopian) respectively. While as the LC50 value of the susceptible population were recorded as 0.002528 per cent. Similarly, for endosulfan the highest LC50 value of 0.061 per cent and resistance factor of 2.45 were observed in Mattan (District Anantnag) and Wagoora (District Baramulla) respectively. However, the lowest LC50 value of 0.027 per cent and resistance factor of 1.08 observed in Rajpura (District Shopian). The LC50 value of the susceptible population were worked out to be 0.02486 per cent. For chlorpyrifos the highest LC50 value of 0.022 per cent and resistance factor of 2.97 were recorded in Achabal (District Anantnag). While as the lowest LC50 value of 0.008 per cent and resistance factor of 1.19 were obtained in Bonkoot (District Bandipora) and Malangpora(District Pulwama) respectively. Similarly the LC50 value of the susceptible population was recorded as 0.006728 per cent. However in case of ethion the highest LC50 value of 0.057 per cent and resistance factor of 2.83 were obtained in Zakura (District Srinagar) while as the lowest LC50 value of 0.025 per cent and resistance factor of 1.24 were recorded in Achabal (District Baramulla), and the LC50 value of the susceptible population was worked out to be 0.02016 per cent. Development of resistance in eight generations of P. ulmi was exhibited when the different generations were exposed to recurrent selection pressure with fenazaquin. When 1st generation was exposed to selection pressure of 0.001 per cent it resulted in no resistance. However, when the 8th generation was exposed to selection pressure of 0.004 per cent, it resulted in 15-fold resistance. This increase in resistance could be attributed to the recurrent selection pressure which may have led to reorganization of genes of the resistant individuals in P. ulmi populations. In this study the genetic variations in P. ulmi populations bred through selection pressure with fenazaquin were analyzed using RAPD-PCR. The comparative RAPD profile with five primers viz., OPA-01, OPF-04, OPF-07, OPR-07 and OPL-08 led to the identification of many polymorphic DNA bands that were amplified in selected population individuals and were absent in susceptible population. This implied that selection pressure of fenazaquin resulted in numerous genetic changes in populations of P.ulmi which could be attributed to resistance development. Resistance factor of 15.0 obtained in 8th generation was found to be associated with 54 per cent genetic similarity as compared to susceptible population which resulted in 95 per cent genetic similarity in generation 1st. These alterations in P. ulmi DNA could be related to unknown genes responsible for imparting resistance of selected populations of P. ulmi. Genetic variation amongst the eleven P. ulmi populations collected from different locations of Valley, and subjected to bioassay to various pesticides were also investigated by RAPD-PCR. The comparative RAPD profile with two primers, viz., OPR-07 and OPL-08 showed high level of genetic variation amongst all the eleven populations evaluated. The genetic similarity in the eleven populations evaluated against endosulfan was computed to be 100 per cent at Shalimar, Zakura and Kunil but it was 55.0 per cent when all the populations were compared with Wagoora population, rest of the population lie in between. Similarly the genetic relatedness of the eleven populations evaluated against dimethoate was computed to be 95.0 per cent at Mattan and Zakura but it was 67.5 per cent when Merihama and Shalimar populations were compared with Wagoora, Malangpora, Kunil, Rajpora and Achabal populations. Whileas Mattan and Zakura populations showed genetic similarity of 77 per cent when compared with Kupwara population. Genetic relatedness of the eleven population evaluated against fenazaquin was recorded to be 100.0 per cent at Shalimar, Zakura, Rajpura and Malangpora and it was 62.6 per cent when the populations from Achabal and Merihama were compared with all other populations. The genetic similarity of the eleven populations evaluated against ethion was computed to be 100.00 per cent at Shalimar, Kunil, Madar, and Malangpora and lowest of 63.0 per cent when all the populations were compared with Merihama population. While as the eleven populations evaluated against chlorpyrifos for genetic relatedness was evaluated to be 100.00 per cent at Wagoora, Kupwara, Mattan Shalimar, Merihama and Rajpora but it was 66.8 per cent when all the populations were compared with Wagoora and Kupwara populations. Highest amount of genetic similarity was observed in populations evaluated against endosulfan while as lowest amount of genetic similarity was registered in populations evaluated against dimethoate