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首页> 外文期刊>International Sugar Journal >Sampling plans for greyback canegrub, Dermolepida albohirtum, to aid management decisions at farm and district level
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Sampling plans for greyback canegrub, Dermolepida albohirtum, to aid management decisions at farm and district level

机译：灰背甘蓝（Dermolepida albohirtum）采样计划，以帮助农场和地区一级的管理决策

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Numbers of greyback canegrubs were monitored in cane fields in central and northern Queensland from 2003-2010. Canegrubs were counted annually from March-May under 20 cane stools in each field. Two different sampling schemes were used in different fields, with stools dug in each of four transects the length of each field, five per transect, or from the four corners and the centre of each field, four per position. Relationships between the mean and variance of grub counts did not differ significantly between the two schemes when calculated over a similar range of means. Mean grub counts did not differ significantly between the inner and outer transects or the central and corner positions in either scheme. Taylor's power law was used to describe the mean-variance relationships for individual fields and for whole districts, and these relationships were used to derive optimal sampling plans. To estimate grub densities in individual fields with a standard error equal to 0.25 of the mean, a sample of 20 stools per field will only be adequate at high grub densities of more than 2 per stool. However, to estimate district-wide grub densities with the same precision, it will usually be better to sample fewer than 20 stools per field and sample more fields. For a given grub density, the optimal number of fields and samples per field depend on the time it takes to sample stools within fields and the cost of travel between fields. The latter will vary greatly depending on the layout of the district and the way a survey is structured- whether a grub survey is a stand-alone activity or done in conjunction with other activities, and the size of the sampling team. More sampling is needed to achieve higher precision of density estimates.
机译：2003年至2010年，在昆士兰州中部和北部的甘蔗田中监测了灰背甘蓝的数量。从3月至5月，每年在每个田地的20个甘蔗凳下对Canegrub进行计数。在不同的田地中使用了两种不同的采样方案，在每个田地的长度的四个横断面中挖出粪便，每个横断面五个，或者从每个田地的四个角和中心挖出粪便，每个位置四个。当在相似的均值范围内进行计算时，两种方案之间的rub虫计数平均值和方差之间的关系没有显着差异。在两种方案中，内，外样线之间或中心和角位置之间的平均g数均无显着差异。泰勒幂定律用于描述单个区域和整个区域的均值-方差关系，这些关系用于推导最佳采样计划。要以标准误差等于平均值​​0.25的方式估计各个田间的g密度，每个田地20个粪便的样本仅在每个凳子大于2的高g密度下才足够。但是，要以相同的精度估算区域范围内的g密度，通常最好每个字段采样少于20个粪便，而对更多字段采样。对于给定的g密度，最佳田间数量和每个田间样本的数量取决于在田间采样粪便所需的时间以及田间之间的旅行成本。后者的变化将取决于地区的布局和调查的结构方式-原始调查是独立活动还是与其他活动结合进行的活动，以及抽样团队的规模。需要更多采样以实现更高的密度估计精度。

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