Study of cucumber plant nutrition effect by different levels of potassium on biological parameters and life table of Tetranychus urticae Koch (Acari, Tetranychidae)

Two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae) is one of the most important pests of cucumber. In order to investigate the effect of different concentrations of potassium on biology and life table of this mite, cucumber plant was nourished by three levels of potassium including deficiency level of potassium K1 (5 meq/l K+), standard level of potassium K2 (7 meq/l K+) and excess level of potassium K3 (9 meq/l K+). The experiments were performed under laboratory conditions at 25±1 C°, 60±5% relative humidity and a photoperiod of 16:8 (L:D) hours. Based on the obtained results, the mean of pre-imaginal developmental time in deficiency, standard and excess levels of potassium was 11.66, 12.15 and 11.35 days for males and 12.2, 11.78 and 10.73 days for females, respectively. The highest mean of females life span was observed in plants which nourished by the lowest concentration of potassium and showed significant different with two other levels of potassium. The maen of oviposition period in mentioned levels was 13.71, 8.18 and 11.72 days, respectively. Also the maximum value of total fecundity was recorded in deficiency level of potassium. Mortality percentage of pre-imaginal stages was estimated 30.74, 23.65 and 20.34% in mentioned levels, respectively. Age specific survival rate (lx) at adult emergence in deficiency, standard and excess levels of potassium was estimated 0.55, 0.66 and 0.73, respectively. The highest value of life expectancy (ex) in the start of the experiments was recorded as 35.31 days in 9 meq/l K+ concentration. The results showed that deficiency of potassium in cucumber plants is caused more reproduction in two- spotted spider mite. So proper management of plant nutrition can be one of the most effective strategies to control this pest in integrated pest management programs.