Investigating the effect of gaucho and cruiser insecticides as seed treatment of Colza in the control of Athalia rosae

Population increase of Athalia rosae L., caused severe damages to many Colza fields of Marivan region in Kurdistan province in 2001. After investigatng the biology of this pest, a study was carried out to control the pest during 2006-2008. Regarding the special characteristics of Gaucho WS (imidacloprid (and Cruiser FS (thiamethoxam), these insecticides were used as seed treatment with 4 doses in a randomized complete block design with 3 replications. Weather conditions and density of larval populations were very different during the two years study period. Results of the first year indicated that the differences between treatments were significant for the number of larvae and yield. Comparing the means revealed that Gaucho and Cruiser dose of 5 g/kg  had no effects on pest control and Cruiser at 7.5, 10 , 12.5 and Gaucho at 12.5 g/kg had the highest effects on the reduction of larval population. Also, Gaucho dose of 10 and 12.5 g/kg had the highest effect on the increase of the yield but Gaucho 5 g/kg had no the effect on the yield increase. In the second year of research, because of dry conditions, the density of larval population was very low but the treatment of seeds caused decrease of larval population significantly and Gaucho 12.5 was the best, but results revealed no differences between treatments for the yield. That is, the densities of pest in the second year can not reduce the yield significantly. The difference between the years for their number of larvae was significant but it was not for their yield.