The sugarcane aphid, Melanaphis sacchari (Zehntner), has emerged as a serious pest of sorghum in the United States. Field trials were conducted in Louisiana and South Carolina in 2016–2018 to investigate its population characteristics and distribution patterns in relation to four sample unit sizes (three circular and one leaf based). Sugarcane aphid populations usually progressed through a phase of rapid rise followed by a phase of rapid decline within a span of 5–6 wk, with peak density determined by sorghum cultivars and climatic conditions. Peak population densities for susceptible cultivars were 1.9–14.9× that for resistant cultivars on a per plant basis. Melanaphis sacchari tended to concentrate on the lower green leaf nodes early in the infestation, with the distribution shifting toward higher green leaf nodes as the infestation progressed. Aphid densities per cm² at the basal and middle sections were about twice as high as at the distal section of leaves. The proportions of infested sample units were fitted to the Wilson–Room binomial model that incorporates the effect of density on clumping pattern. For a specific sample unit size, clumping patterns were similar across cultivars, years, and leaf positions, but varied across infestation stages. For a fixed aphid density per sample unit, the proportion of infested sample units decreased with increasing sample unit size. For a fixed aphid density per cm², proportion infested increased with increasing sample unit size, indicating less clumping with a larger sample unit size. Field sampling time and efficiency between samplers were quantified.

中文翻译：

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高粱上的甘蔗蚜虫（半翅目：蚜科）。一、与不同样本单位规模相关的人口特征和分布模式

甘蔗蚜虫Melanaphis sacchari (Zehntner) 在美国已成为严重的高粱害虫。2016-2018 年在路易斯安那州和南卡罗来纳州进行了田间试验，以调查其与四个样本单位大小（三个圆形和一个基于叶子的）相关的种群特征和分布模式。甘蔗蚜虫种群通常在 5-6 周内经历快速上升阶段和快速下降阶段，其峰值密度由高粱品种和气候条件决定。以单株为基础，易感品种的种群密度峰值是抗性品种的 1.9-14.9 倍。蜜饯在侵染初期倾向于集中在较低的绿叶节点上，随着侵染的进行，分布向较高的绿叶节点转移。^{基部和中部每cm 2}的蚜虫密度约为叶片远部的两倍。受侵染的样本单位的比例符合 Wilson-Room 二项式模型，该模型结合了密度对聚集模式的影响。对于特定的样本单位大小，不同品种、年份和叶片位置的丛集模式相似，但在侵染阶段不同。对于每个样本单位固定的蚜虫密度，受侵染的样本单位的比例随着样本单位大小的增加而降低。^{对于每 cm 2}固定的蚜虫密度，受侵染的比例随着样本单位大小的增加而增加，表明随着样本单位大小的增加而聚集较少。量化了采样器之间的现场采样时间和效率。