Abstract: 【Aim】 To explore the ecological regulation effectiveness of habitat heterogeneity on predatory natural enemies and rice pests in rice paddies, and to determine whether this strategy would cause other herbivorous insects to become main rice insect pests. 【Methods】 Single-season rice was planted for two consecutive years (2017-2018). Peanuts and soybeans were planted at the edge of rice paddy to construct the rice paddy with high heterogeneous marginal habitats (HHR). The occurrence and correlation of predatory natural enemies and rice pest functional groups in both HHR paddy and rice paddy with low heterogeneous marginal habitats (LHR) were investigated, and the predator-to-pest ratio was calculated. 【Results】 In 2017, 1 667 predatory natural enemies belonging to 40 species were collected in HHR, and 991 predatory natural enemies belonging to 30 species were collected in LHR. In 2018, 1 384 predatory natural enemies belonging to 33 species were collected in HHR, and 1 031 predatory natural enemies belonging to 34 species were collected in LHR. The similarities of species of the predatory natural enemies with the community importance value P_i≥0.01 in HHR and LHR were high, and the dominant species in the two paddies were similar. In 2017, the species richness of predatory natural enemies in HHR was significantly higher than that in LHR, which was mainly caused by the species with the community importance value P_i<0.01. There was no difference in the species richness of predatory natural enemies between the two paddies in 2018. The number of predatory natural enemies in the quadrat area in HHR was higher than that in LHR, and this difference was significant in the tillering and maturity stages in 2017 (P<0.05), and extremely significant in the flowering stage in 2018 (P<0.01). In 2017, 637 rice pests belonging to 22 species were collected in HHR, and 743 rice pests belonging to 19 species were collected in LHR, with the similarity coefficient of community of 0.88 between the two paddies. In 2018, 1 011 rice pests belonging to 16 species were collected in HHR, and 2 014 rice pests belonging to 16 species were collected in LHR, with the similarity coefficient of community of 0.75 and the same compositions of main pest species between the two paddies. The temporal dynamic analysis of rice insect pest populations showed that the number of insect pests in HHR was significantly higher than that in LHR (P<0.05) in the tillering stage when the total number of insect pests was small and their damage to rice was light. In the booting stage, flowering stage and maturity stage, the numbers of rice pests in HHR were significantly lower than those in LHR, and this difference was extremely significant in the maturity stage in 2017 and the booting stage in 2018 (P<0.01), and significant in the maturity stage in 2018 (P<0.05). The N_pi (the individual number ratio of predatory natural enemies to insect pests) values in HHR and LHR were 2.62 and 1.33 in 2017, and 1.37 and 0.51 in 2018, respectively. 【Conclusion】 The rice paddy with high heterogeneous marginal habitats can improve the conservation potential of predatory natural enemies, and significantly increase the number of predatory natural enemies and the predator-to-pest ratio in rice paddy. This makes up a better material basis for controlling pests, can promote the ecological control efficacy of predatory natural enemies on rice pests, and has no risk of causing other herbivorous insects to evolve into main rice pests, providing strategies and methods for protecting the natural enemies in rice ecosystems.

Key words: Rice paddy, habitat heterogeneity, predatory natural enemies, rice insect pests, ecological regulation