Evaluation releasing of parasitoid wasp Trichogramma brassicae with other methods for the control of rice striped stem borer (Chilo suppressalis) in field conditions

The striped stem borer is a serious pest of rice in the northern provinces of Iran, which is found in all stages of its growth from nursery to paddy field. It causes qualitative and quantitative damage on rice. Nowday, with the expansion the development of problems due to chemical control, other methods of pests management especially biological controlhas a special place in agriculture is rice. Accordingly, in order to study one factor affecting the role of biological control agents (Tricogramma) compared to other control methods. In this research,five different treatments, including biological control three, two and one-year-old, chemical control and cultural controlto reduce the population of rice striped stem borerin two city of Guilan province were evaluated in paddy fields. The results showed that rice striped stem borer population flactuations in three-year of biological control had a decreasing trend and its natural enemies population hadan increasing trend.Furthermore, results of this study indicated that the average number of natural enemies collected during the season in biological control of three, two and one year old, cultural and chemical controls, 679, 589, 469, 447 and 396 number was, respectively. This study also showedthat all treatments in terms of yield levels had significantly different from each other. The highest yield on three-year biological and chemical control methods was observed. 3677 and 3650 kg per hectare, respectively.Based on the results obtained, two time release of Trichogramma in each generation of rice striped stem borer and during three consecutive years,hadthe highest effective compared to other methods used in the control of rice striped stem borer in paddy field.