evaluation of the effectiveness of fipronil insecticide in control of chilo suppressalis walker in the paddy field

long –term use of some of insecticides on rice striped stem borer (chilo suppressalis walk.) and for the reason the urgency of use of new suspension insecticide an experiment carried out, in paddy fields under condition at rice research institute in rasht, iran.treatments were as follow;1-fipronilg in first generation 2-fipronil g. in second generation 3-fipronil sc in first generation 0.5 lit.4-fipronil sc in second generation 0.5lit. 5-fipronil sc in first generation 1lit. 6-fipronil sc in second generation 1lit. and control. this experiment was conducted with randomized complete block design(rcbd) in 3 replications. indexes of measurement were included d.h% , w.h%, the alive larvae percentage before &after; the first and the second of pest and yield.the results indicated that the lowest rate of d.h at first generation was with granular 20kg. and suspension one lit. per ha. with 5.63, 5.57 percent, respectively. also, in the second generation, the lowest rate of w.h showed in fipronil g with 3.64% and sc 1and 0.5 lit/ha with 4.24 ,4.96%, respectively. the yield of treatments, control except had not significant in 1% level. the highest of insecticidal efficiency in first generation, related to in fipronil granular 53.84 and sc(1 and 0.5 lit/ha) with 45.29 and 44.75, and in second generation, observed with formulations of granular and sc 1lit/ha with 56.55 and 56.15 % ,respectively. therefore, when we confronted with population increasing ssb, we can use fipronil sc(1lit/ha) in second generation.