مصطفی خنامانی

Cultural methods such as crop fertilization can affect susceptibility of plants to herbivores by altering plant tissue nutrient. In this study, the life table parameters of the two-spotted spider mite (TSSM), Tetranychus urticae Koch were determined under different chemical fertilizer regimes on resistant bean cultivar (var. Parastoo) under laboratory conditions at 25 ± 1°C, 60 ± 5% RH and a photoperiod of 16:8 (L:D) h. Treatments included three levels (30, 60 and 100% of the recommended level) of urea, ammonium nitrate and potassium sulfate fertilizers. According to the obtained results, the longest preadult development time was related to individuals reared on the fertilized bean with potassium sulfate 60% and the shortest period was related to those on ammonium nitrate 30% and urea 60%. The mean fecundity of the individuals reared on fertilized beans with different concentrations of ammonium nitrate (especially ammonium nitrate 60%) were significantly higher than those reared on the other fertilizers. The highest and lowest values of intrinsic rate of increase (r) were obtained on fertilized beans with ammonium nitrate 60% and potassium sulfate 100%, respectively. In addition, the values of net reproductive rate (R0) and the gross reproductive rate (GRR) of TSSM reared on fertilized bean with ammonium nitrate 60% were significantly higher than those estimated on the other fertilizer treatments. Our findings may provide important information in the design of a comprehensive program for integrated soil fertility management and subsequently integrated management of TSSM in bean fields.