Abstract: 【Objective】Increasing plant diversity is an effective way for sustainable pest control through trapping pests, protecting natural enemies. Host plants of rice leaffolder (Cnaphalocrocis medinalis) include rice and some graminaceous plants. The objective of this study is to develop a new strategy of C. medinalis control based on the preference of C. medinalis to graminaceous plants and rice plants. 【Method】Seven common graminaceous weeds (Leersia sayanuka, Paspalum distichum, Digitaria sanguinalis, Leersia hexandra, Leptochloa chinensis, Echinochloa crusgalli, and Eleusine indica) around rice fields were selected as the potential hosts in the experiments. These weeds were planted in pots and were placed into cages with rice plants, C. medinalis adults were also introduced into the cages, then thehabitat and oviposition preference of C. medinalis to graminaceous weeds and rice, and the biological fitness of C. medinalis on graminaceous weeds were studied. Furthermore, the effects of graminaceous weeds, which were planted on bund as 1 m width, on the distribution and oviposition of C. medinalis and egg parasitoids were evaluated in rice fields. Meanwhile, population density of C. medinalis in bund planted with different graminaceous weeds and that in the site with 1, 5 and 10 m from bund were recorded by chasing moth method. Number of C. medinalis eggs, parasitized eggs and parasitism rate on different graminaceous weeds in the field were also investigated. 【Result】C. medinalis adults prefer to the habitat of L. sayanuka and D. sanguinalis, and do not prefer P. distichum. There was no significant difference between L. hexandra, E. indica, L. sayanuka, L. chinensis and rice. C. medinalis adults prefer to lay eggs on rice compared with L. sayanuka, E. crusgalli, E. indica, L. chinensis, P. distichum and L. hexandra. L. sayanuka significantly attracted C. medinalis adult to lay more eggs than rice. No significant difference on oviposition preference was found between D. sanguinalis and rice. C. medinalis could complete their generation on all seven tested graminaceous weeds. However, significant difference on development time was detected among treatments. Lowest development time was found on L. sayanuka, followed with P. distichum. There was no significant difference on development time among L. hexandra, L. chinensis, E. indica, D. sanguinalis, E. crusgalli and rice. Plant hosts significantly impact the pupal weight. Female pupal weight from D. sanguinalis, male pupal weight from D. sanguinalis and L. chinensis were significantly lighter than those from the other host plants. The emergence rates of C. medinalis from different host plants varied largely, which from L. sayanuka, L. hexandra, E. indica, E. crusgalli, and rice were ranged from 42.17%-51.31%; but which fromL. chinensis and P. distichum were as low as 11.76% and 13.29%, respectively. Female rate of C. medinalis reared on rice and E. crusgalli was significantly higher than those reared on the other host plants. Field experiments indicated that graminaceous weeds could attract more C. medinalis adults than rice, except E. indica and E. crusgalli. There were significant differences on the number of C. medinalis eggs on different graminaceous weeds, which was ranged from 2.92-3.92 per tiller on L. sayanuka, L. hexandra, E. crusgalli and L. chinensis. The mean number of C. medinalis eggs on P. distichum and D. sanguinalis was 2.16 and 1.72, respectively; and lowest eggs on E. indica. The parasitism rate of C. medinalis eggs by egg parasitoids was varied significantly among different graminaceous weeds, ranged from 21.90%-55.61%. The mean number of parasitized C. medinalis eggs was 1.47 and 1.42 per tiller on L. sayanuka and L. hexandra,respectively, which was highest than those on the other graminaceous weeds. 【Conclusion】The results imply that L. sayanuka has the most potential to be used as a functional plant for controlling C. medinalis. The results could provide a theoretical foundation for developing new green C. medinalis management technology.

Key words: Cnaphalocrocis medinalis, graminaceous weed, host plants, habitat selection, oviposition selection, ecological fitting, functional plant