Effect of nitrogen and phosphorus on damage of two-spotted spider mite (Tetranychus urticae Koch) on bean (Phaseolus vulgaris L.)

In order to study the interaction effects of nitrogen and phosphorus in two-spotted spider mite (Tetranychus urticae Koch) on chiti bean, sadri variety, this experiment was conducted in 2012–13 at the Agricultural Research Station of Islamic Azad University, Arak Branch, Iran. A factorial experiment was arranged in randomized complete block design with three replications. Three levels of nitrogen (as urea 46% N) including no application (N₁), 75 kg/ha (N₂) and 150 kg/ha (N₃) and three levels of phosphorus as di phosphate ammonium, no application (P₁), 100 kg/ha (P₂) and 200 kg/ha (P₃) were used. Each day the number of deaths and the number of eggs was counted. In this paper, the life expectancy (LEx) of 1, 5, 15, 20, 25 and 30 days after infection has been studied. Results showed that nitrogen increased the establishment of the plant mite in days after infection and that phosphorus application in plants reduced life expectancy 20, 25 and 30 days after infection.