关键词: 吡虫啉, 种衣剂, 玉米, 节肢动物群落, 非靶标害虫

Abstract: 【Objective】The objective of this study is to investigate the effects of imidacloprid flowable concentrate for seed coating (FSC) on the arthropod community and the non-targeted insects in maize field, in order to provide a theoretical basis for the application of seed coating agent.【Method】The study was conducted in the experimental field in Xuchang Campus of Henan Agricultural University from June to September in 2015 and 2016, respectively. Maize seeds were coated with the recommended dose of 600 g·L^-1 imidacloprid FSC and its doubled and quadrupled dose, with water as control. Each treatment was repeated for 4 times and arranged with randomized block. The density of the arthropods in maize field was estimated by using 5 sampling spots methods, each spot with 10 tagged plants at seedling, bellmouthed, booting and filling stages of the maize plants. The characteristics of the arthropod community including arthropod species and their amounts in different treatment areas were analyzed. In order to analyze the effects of imidacloprid FSC on non-targeted insects, the amount of insect pests in maize ears within the sampling spots at filling stage and the amount of lepidopteran larvae in maize ears and stalks by sampling 100 plants within two lines at mature period were surveyed. 【Result】Imidacloprid FSC treatment had no effect on the number of species of arthropod in maize field, and the species richness in the treatment areas showed similar change trend to that in the control area. The difference of the richness in different treated plots at the same time was related to the low density and uneven distribution of some species. Seed coating could not lead to the decrease of the diversity and evenness of the arthropod community. When the population of target pest, Rhopalosiphum maidis, occurred at high level, the diversity and evenness in seed coating areas could be increased by inhibiting the target pests. The effects of imidacloprid FSC on the dominant species differed with maize growth stages in different years. In 2015, R. maidis occurred at higher population density, the dominant species of the phytophagous insects and predators in seed coating plots were similar to that in control plot at early growth stage of maize, while Pseudaletia separata and Erigonidium graminicolum were the dominant species in plots of 2 times and 4 times doses of maximum recommended doses (MRD). In 2016, when R. maidis occurred at lower population density, Ostrinia furnacalis and Helicoverpa armigera were dominant phytophagous species, and Propylea japonica and Harmonia axyridis became the dominant species of predators. The dominance degree showed similar change trend to dominant concentration index. The impact of seed coating on ear-feeding lepidopteran larvae was complex. For example, the population density of O. furnacalis in the treated plots was higher than or equivalent to that in the control plots during early and middle grain-filling, and the density of Dichocrocis punctiferalis larvae also increased significantly at the early grain-filling stage, but decreased at the middle grain-filling stage. For P. separata, the density in seed coating plots increased significantly than that in control plot at middle filling stage, while the density of H. armigera in seed coating plots differed from the check plots with no remarkable degree. The results of the two-year investigations showed that the density of O. furnacalis, D. punctiferalis and P. separata had an increasing trend in seed coating plots, but it was not closely related to the dosage of seed coating agent of 600 g·L^-1 imidacloprid. 【Conclusion】It is recommended that lepidopteran pests should be prevented or controlled in the maize field with application of imidacloprid coating agent.

Key words: imidacloprid, seed coating agent, maize, arthropod community, non-target pests