Dynamics and temporal niches of major pest insects and their natural enemies in perennial rice fields
Author of the article:YANG Shao-Wu；ZHANG Xiao-Ming；GUO Hai-Ye；DU Chun-Ze ；QUAN Yun-Chou；FU Yang；CHEN Guo-Hua
Author's Workplace：College of Plant Protection, Yunnan Agricultural University, National Key Laboratory for Conservation and Utilization of Biological Resources in Yunnan, Kunming 650201, China；College of Plant Protection, Yunnan Agricultural University, National Key Laboratory for Conservation and Utilization of Biological Resources in Yunnan, Kunming 650201, China；College of Plant Protection, Yunnan Agricultural University, National Key Laboratory for Conservation and Utilization of Biological Resources in Yunnan, Kunming 650201, China；College of Plant Protection, Yunnan Agricultural University, National Key Laboratory for Conservation and Utilization of Biological Resources in Yunnan, Kunming 650201, China；College of Plant Protection, Yunnan Agricultural University, National Key Laboratory for Conservation and Utilization of Biological Resources in Yunnan, Kunming 650201, China；College of Plant Protection, Yunnan Agricultural University, National Key Laboratory for Conservation and Utilization of Biological Resources in Yunnan, Kunming 650201, China；College of Plant Protection, Yunnan Agricultural University, National Key Laboratory for Conservation and Utilization of Biological Resources in Yunnan, Kunming 650201, China
Key Words：perennial rice; main pest insects; main natural enemies; population dynamics, temporal niche
Abstract：[Objectives] To clarify the occurrence of the main pest insects and their natural enemies in perennial rice fields, analyze the temporal relationships between these pests and their natural enemies, and provide a scientific basis for controlling pests of perennial rice crops. [Methods] The five point sampling method, incorporating sweep sampling, plate beating, visual inspection and trapping, was used to record the number of insects in perennial and conventional rice fields in two different rice planting areas in Yunnan Province. [Results] In the first growing season of conventional rice crops, the main pest insects were the rice planthopper Chilo suppressalis, Tryporyza incertulas and Cnaphalocrocis medinalis, and their main predators were Sepedon sphegeus, Tetragnatha nitens and Indolestes cyaneus. However, in the second growing season, the main pest insects were the rice planthopper and C. medinalis, and the main predators were S. sphegeus and Cyrtorrhinus livdipennis. In perennial rice crops, the main pest was C. medinalis and the main predators were S. sphegeus and C. livdipennis, both of which also occurred in the third and the fourth growing seasons. The species and dynamics of pest insects and their natural predators differed during different growing seasons in the two planting areas. The abundance of the rice planthopper, and the percentage damage caused by C. medinalis, were higher in the second than in the first growing season in conventional rice crops, and the percentage damage caused by C. medinalis was higher in the third than in the fourth growing season in perennial rice crops. The temporal niche of C. medinalis in the two different planting areas was larger than that of other pests; it appeared earlier and persisted longer than other pest insects in perennial rice fields. The rice planthopper had a smaller temporal niche and a briefer period of occurrence than other pest insects. Its main natural enemies were T. nitens, I. cyaneusand C. livdipennis. [Conclusion] The main pest insects and their natural enemies in perennial rice fields differed between two different rice planting areas. There was higher pest abundance and crop damage in the second than in the first growing season in conventional rice crops, but in perennial rice crops there were more pests and more crop damage in the third than in the fourth growing season. In perennial rice crops, Tetragnatha nitens, I. cyaneusand C. livdipennis were the main natural enemies of pest insects. Greater emphasis should be placed on protecting the natural predators of pest insects as a means of reducing crop damage in perennial rice fields.