关键词: 观赏水稻, 稻纵卷叶螟, 产卵选择性, 生态适应性, 寄生偏好

Abstract:

【Objective】The application of colorful rice in field painting is an important part of creative agriculture, but it may affect the occurrence and damage of the main pests in paddy field. The objective of this study is to investigate the effects of colorful rice on Cnaphalocrocis medinalis and its egg parasitic wasps, and to provide a theoretical basis for the control of C. medinalis in creative agriculture.【Method】The biological characteristics of C. medinalis in purple rice, yellow rice and common rice (control) were compared, including the developmental duration of larval and pupal stage, survival rate of larvae and pupae, pupal weight and sex ratio. The oviposition selectivity of C. medinalis, and parasitic selectivity of its important egg parasitoids (Trichogramma chilonis and Trichogramma japonicum) between colorful rice and common rice were also compared. The occurrence of C. medinalis in colorful rice paddy field and creative field painting with purple rice was investigated as well.【Result】The results of laboratory test showed that C. medinalis preferred to lay eggs on colorful rice, and the percentage of egg laying on colorful rice was more than 60%, which was significantly higher than that of green common rice. The ecological fitness of C. medinalis on colorful rice was higher than that on green common rice. The larval and pupae survival rates of C. medinalis fed with purple rice and yellow rice were significantly higher than those of common rice. The colorful rice had no significant effect on the developmental duration, pupal weight and sex ratio of C. medinalis. The parasitic selectivity of different Trichogramma species to the eggs of C. medinalis on different rice varieties was different. T. chilonis preferred to parasitize the C. medinalis eggs laid on purple rice, and had the lowest parasitic selectivity on yellow rice, but the parasitic rate had no significant difference. However, T. japonicum preferred to parasitize the eggs laid on green common rice, and had the lowest selectivity of the eggs laid on purple rice. The parasitic rate of T. japonicum on the eggs of common rice was 4.3 times higher than that of purple rice and 2.1 times higher than that of yellow rice when three kinds of rice existed at the same time. The rate of rolled leaf caused by C. medinalis and the larva density in colorful rice field were significantly higher than those in common rice field. The rate of rolled leaf in purple rice area was the highest (15.3%), which was 10.9 times of that of common rice and 3 times of that of yellow rice. The residual rate of C. medinalis in purple rice and yellow rice was 4.5% and 3.3%, respectively, which was significantly higher than that of common rice (1.1%). When purple rice was used to write Chinese characters in paddy field, the rate of rolled leaf in purple rice was above 6%, which was significantly higher than that in common rice field (below 4%). 【Conclusion】Compared with common rice, colorful rice is easier to attract C. medinalis, and the ecological fitness of C. medinalis on colorful rice is higher than that of common rice, while T. japonicum has the lowest selectivity to C. medinalis eggs on purple rice. It is unfavorable to biological control of C. medinalis on purple rice. The negative ecological effects should be fully considered when using colorful rice to paint the creative agricultural paddy fields, and corresponding control strategies should be worked out.

Key words: ornamental rice, Cnaphalocrocis medinalis, oviposition preference, ecological fitness, parasitic preference