evaluating the efficiency of trichogramma pintoii and bacillus thuringiensis var. kurstaki on corn stem borer, ostrinia nubilalis (lepidoptera:pyralidae) in corn fields of moghan plain

objective: in this study the efficacy of two agent of this biological control agent of corn stem borer in corn fields compared with common synthetic insecticides endosolfan to find a suitable alternative for chemical control of pests in corn fields. methods: in order to evaluate the efficiency of biocontrol agents of corn stem borer ,ostrinia nubilalis, experiment was conducted in a randomized complete block by five treatments and four replication, including, indoxacarb (avant), trichogrammawasps, bacillus thuringiensis var: kurstaki, integration of trichogramma sp. and bt., and control as treatments number 1 to 5. in treatments with parasitoid release, four days after releasing the wasps, the number of parasitized eggs was recorded. in each plot, 20 plants were randomly selected for recording the number of the larval holes on corn stems. the number of damaged stems was recorded on the same number of corn plants before harvest. statistically analysis of data was carried out by using minitab software. results: in treated plots by egg parasitoid wasp, the range of egg parasitism was 10 to 28 percent. the number of larval holes was 1.05, 1.30, 1.55, 1.38, and 2.04 per plant in treatments number 1, 3, 4, and 5 respectively. there was significant difference among the treatments considering the number of larval holes. the number of damaged stem in treatments number 1, 3, 4, and 5 were 0.17, 0.59, 0.98, 0.80 and 1.60 per plant, respectively. there was significant difference among the treatments considering the number of damaged stems. despite this, there was no significant difference among biological control treatments in the number of larval holes and number of damaged stems. the achieved results from present study were revealed that the efficiency of the egg parasitoid wasp, trichogramma sp. is lower than examined bt.