Population Abundance, Prey Consumption and Body Size of the Predatory Bug Orius minutus Feeding on Tetranychus urticae on Six on Six Potato Cultivars

Two-spotted spider mite، Tetranychus urticae Koch، is a pest of potato crop in Ardabil region. Throughout the study، the population densities of T. urticae and Orius minutus L. were assessed on six cultivars of potato crop under field conditions during years 2011 and 2012. Also، the attraction rate and the body size of O. minutus were studied on six cultivars of potatoinfested with T. urticaeunder laboratory conditions. The lowest mite density (71. 1 prey/plant) and the highest predator population (3. 3 predator/plant) were recorded for Savalan. After 24، 48 and 72 hours past from release، the predators were significantly more attracted to two-spotted spider mite-infested leaves of Savalan (as compared with the other tested cultivars). The female predators reared on the two-spotted spider mite-infested leaves of Savalan cultivar were of higher body mass and greater body sizes among the six tested cultivars of the potato crop. The prey consumption per O. minutus nymphs on Savalan was significantly higher than that occurring on Kondor and Diamant cultivars. Therefore، it can be concluded that cultivation of Savalan potato cultivar integrated with O. minutusas as a biological control agent could be practically useful in the integrated management of T. urticae in the potato fields of Ardabil.