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Abstract:
The rice stem borer, Chilo suppressalis (Walker) (Lepidoptera: Crambidae), is one of the most important pests in rice cultivation. Today, with the spread of problems resulting from the implementation of chemical control methods, such as the excessive use of chemical pesticides and environmental pollution, pest management methods, especially biological control, have a special place. Accordingly, this research was conducted on one of the biological control agents (Trichogramma wasp) against the rice stem borer (Chilo suppressalis). Until now, rice farmers have been releasing Trichogramma wasps against stem-eating pests using Trichocards in rice fields. However, due to the inefficiency and lack of acceptance by farmers and dissatisfaction with the use of Trichocards, it is necessary to use newer methods to make the bees more effective in the rice fields. This research was conducted over two years from 1402 at the Rice Institute Research field. In this research, 4 treatments were used including 1- releasing Trichogramma wasps with Trichocapsule, 2- releasing Trichogramma adult insects inside the can by hand, 3- releasing Trichogramma with Trichocard, 4- control (without Trichogramma wasps). The results of the first year of the study showed that the highest average total parasitism in the first generation of the pest in 1402 was related to the Trichocapsule treatment with 39.01 percent, the average total parasitism was related to the Trichocard with 28.55 percent, and the average parasitism in the can release method was 25.12 percent. Also, the highest parasitism in the second generation of the pest in 1402 was related to the Trichocapsule release treatment with 60.28 percent, and the lowest was related to the Trichocard treatment with 30.50 percent. The results of this study showed that the highest number of dead central buds in the vegetative stage of the rice plant and in the first generation of the pest in 1402 was observed in the control treatment with 46.19% infection, and the lowest number of dead central buds was observed in the Trichocapsule method with 7.95% infection. Also, in this study, in the second generation of the pest, the most whitened clusters were observed in the control treatment with 20.26% infection and the least whitened clusters were observed in the Trichocapsule treatment with 6.98% infection. The results of this study showed that the average yield in 1402 related to the Trichocard, Trichocapsule, and can treatments did not differ significantly from each other, but a significant difference was observed with the control treatment, so that the highest yield was observed in the Trichocapsule release method with a yield of 3767.08 kg/ha. Meanwhile, the control treatment was observed to have the lowest yield of 3370.93 kg/ha. Studies in the second year of 1403 research showed that the highest average total parasitism in the first generation of the pest was related to the Trichocapsule treatment with 59.98 percent, the average total parasitism was related to Trichocard with 47.10 percent, and the average parasitism in the can release method was 49.51 percent. Also, the highest parasitism in the second generation of the pest and in 1403 was related to the release treatment with Trichocapsule with 66.93% and the lowest was related to the Trichocard treatment with 32.73%. The results of this study in 1403 showed that the highest number of dead central buds was observed in the vegetative stage of the rice plant and in the first generation of the pest related to the control treatment with 18.39% infection and the lowest number of dead central buds was observed in the Trichocapsule method with 7.51% infection. In this study, in the second generation of the pest, the highest number of whitened clusters was observed in the control treatment with 13.23% infection, and the lowest number of whitened clusters was observed in the Trichocapsule treatment with 7.31% infection. In this study, the average yield in the Trichocard, Trichocapsule, and can treatments in 1403 did not differ significantly from each other, but a significant difference was observed with the control treatment, so that the highest yield was observed in the Trichocapsule release method with a yield of 3877.48 kg/ha. Meanwhile, the control treatment was observed to have the lowest yield of 3362.21 kg/ha. Therefore, for integrated management of stem borer in biological control, the most suitable method of releasing Trichogramma wasp is using Trichocapsule.
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