Department of Biological Sciences, Florida International University, Miami, Florida 33 199, USA.
J Insect Sci. 2011;11:124. doi: 10.1673/031.011.12401.
Stigmacoccus garmilleri Foldi (Hemiptera: Margarodidae) is an ecologically important honeydew-producing scale insect associated with oak trees (Quercus spp.) in highland forests of Veracruz, Mexico. The honeydew exudates of S. garmilleri serve as a significant nutrient source to many species of birds, insects, and sooty molds. Oak trees found in the forest interior, forest edge, and those scattered in pasture areas support scale insect colonies, though the pattern of insect infestations on trees within these varying landscape types has not been elucidated. This study aims to describe the distribution of scale insect infestation and any distinctions in honeydew production based on tree location. Scale insect density, honeydew volume, and sugar concentration were surveyed throughout a continuous landscape that included both patches of forest and scattered pasture trees. In addition, the anal filament through which the honeydew drop is secreted was also measured and was experimentally removed to test and measure regrowth. Scale insect densities on tree trunks were greatest on pasture trees, while intermediate densities were found on trees at the forest edge, and low densities on interior forest trees, suggesting that trees in disturbed areas are more susceptible to scale insect infestation. Trees with small diameters at breast height had significantly higher insect densities than trees with medium to large diameters. Trunk aspect (North, South, East, and West) was not a significant determinant of scale insect density. In forested areas higher densities of scale insects were found at three meters height in comparison to lower heights. Sugar concentrations and drop volumes of honeydew in forest and pasture areas were not significantly different. However, scale-insect anal tubes/filaments were significantly longer in pasture than they were in forests. Sugar concentrations of honeydew appeared to be positively correlated with temperature and negatively correlated with relative humidity. Experiments indicated that anal filaments could grow approximately 4 mm every 24 hours, and average tube growth was significantly faster in pasture than in forest, suggesting that there may be a physiological effect on the insect due to landscape disturbance. The results obtained in this study describe the increases in scale insect infestation of trees with forest disturbance. The effect of these increased scale insect densities on the host tree physiology is still to be resolved.
加利福尼亚蜡蚧（Hemiptera：Margarodidae）是一种生态上重要的蜜露分泌性介壳虫，与墨西哥韦拉克鲁斯高地森林中的栎属树木（Quercus spp.）有关。S. garmilleri 的蜜露分泌物是许多鸟类、昆虫和煤烟霉菌的重要营养来源。森林内部、森林边缘和散布在牧场区域的栎树支持着介壳虫群体，尽管这些不同景观类型中树木上的昆虫感染模式尚未阐明。本研究旨在描述介壳虫感染的分布以及基于树木位置的蜜露产量的任何差异。在包括森林斑块和散布的牧场树木的连续景观中，调查了介壳虫密度、蜜露量和糖浓度。此外，还测量了分泌蜜露滴的肛毛，并将其实验性去除以测试和测量再生。树干上的介壳虫密度在牧场树木上最高，而在森林边缘的树木上则为中等密度，在森林内部的树木上则为低密度，这表明受干扰区域的树木更容易受到介壳虫感染。胸径较小的树木的昆虫密度显著高于胸径中等至较大的树木。树干的朝向（北、南、东、西）不是介壳虫密度的重要决定因素。在森林地区，三米高处的介壳虫密度高于较低高度。森林和牧场地区的蜜露糖浓度和滴体积没有显著差异。然而，在牧场中发现的介壳虫肛管/肛毛明显比在森林中长。蜜露的糖浓度似乎与温度呈正相关，与相对湿度呈负相关。实验表明，肛毛每 24 小时可生长约 4 毫米，并且在牧场中的平均管生长速度明显快于在森林中，这表明由于景观干扰，昆虫可能会受到生理影响。本研究获得的结果描述了树木受森林干扰时介壳虫感染的增加。这些增加的介壳虫密度对宿主树生理学的影响仍有待解决。
