| Popis: |
Within-tree distribution of an insect pest is useful to determine sample unit, sampling location, and required sample number for this pest within a tree. This study was conducted to characterize the within-tree distribution pattern and determine an efficient sample unit for eggs of Ricania shantungensis (Hemiptera: Ricaniidae) on a chestnut tree. A total of 60 chestnut trees were randomly selected from chestnut fields in Gongju-Si and Buyeo-Gun, Korea in 2019. For each tree, 12 branches were cut at three vertical heights (low, middle, and high) in four cardinal directions (east, west, south, and north). The cut branches were observed for counting the number of egg masses per 10 cm from the branch tip. Coefficient of variation (CV) and coefficient of determination (r2) were calculated and used to determine an optimal sample unit for eggs of R. shantungensis on chestnut trees. Numbers of R. shantungensis egg masses were not significantly different (P > 0.05) vertically and horizontally within a tree. Based on CV and r2 values, the 50 cm branch tip would be the optimal sample unit for R. shantungensis eggs. Using this small sample unit for sampling of R. shantungensis eggs could be economical and efficient. |
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