Composition structure and spatial distribution of white grubs in upland rice field in Yunnan

【Objective】To identify the species composition,population spatial distribution pattern and sampling method of white grubs in upland rice field of mountain area in Yunnan,which provided a reference for the prediction and comprehensive control of white grubs in upland rice field. 【Method】The white grub population was systematically investigated and identified by five-point sampling method in 2022 and 2023 in three main upland rice growing areas, Haozhiba Village, Haguoma Village and Nuoguo Village of Zhutang Township, Lancang County, Pu'er City, Yunnan Province.Aggregation index method,Iwao regression analysis,Taylor power function method and population aggregation mean were used to analyze the spatial distribution patterns and aggregation reasons of white grubs in different experimental sites. Based on the spatial distribution results,theoretical sampling and sequential sampling models were formed. 【Result】A total of 9 species of white grubs belonging to 6 genera and 3 families were found in 3 experimental sites in Lancang County,Pu'er City,Yunnan Province. Apogonia cupreoviridis and Maladera orientalis were the dominant species. The relative abundances were 30.91% and 24.18%,respectively. The aggregation index method,Iwao regression analysis and Taylor power analysis showed that the spatial distributions of white grub in Haozhiba Village,Haguoma Village and Nuoguo Village in 2022 and 2023 were all aggregation distributions(α<0,β>1). And the aggregation mean λ values were greater than 2,the results showed that the living habits of insects, environmental climate, soil moisture and plant growth were the main factors affecting the aggregation of grubs in upland rice field. Through the establishment of theoretical sampling and sequential sampling model, when the allowable error D was 0.3 and the white grub population density in Haozhiba Village,Haguoma Village and Nuoguo Village was 2 insects/m²,the required theoretical sampling numbers were 353,393 and 155 m² in 2022,and 76,44 and 49 m² in 2023 respectively. 【Conclusion】A total of 9 white grub species are found in upland rice fields in 3 villages of Zhutang Township,Lancang County,Pu'er City,Yunnan Province. The main dominant species are A. cupreoviridis and M. orientalis, and the grub populations are all aggregated in the field in individual groups,which are caused by the living habits of insects, environmental climate, soil moisture and plant growth conditions.