Leaf-cutting ants of the genus Atta are an important insect pest in forest plantations in many countries of South America. The objective of this work was to evaluate the potential for using Landsat-8 images, with medium spatial resolution and distributed free of charge, to detect leaf-cutting ant nests in Tectona grandis plantations in Brazil, using partial least squares discriminant analysis (PLS-DA). The regression model adjusted by PLS-DA selected three principal components with a cross-validation error of 0.275 to map and predict the presence of leaf-cutting ant nests in these plantations. The most important bands and vegetation indices were selected using the main variables in the projection (VIP) and predicted pixels with the presence or absence of leaf-cutting ant nests with an accuracy of 72.3% on an independent validation data set. The study indicates that Landsat-8 OLI images have the potential to detect and map leaf-cutting ant nests in T. grandis plantations.
insecticides are the main method of controlling lepidopteran pests of eucalyptus plantations and those selective to natural enemies, such as the endoparasitoid Palmistichus elaeisis Delvare et LaSalle (Hymenoptera: eulophidae), are preferable. the objective of this study was to evaluate the selectivity and effects on biological parameters of the insecticide deltamethrin, registered for the control of defoliator caterpillars of eucalyptus, to the parasitoid P. elaeisis aiming the rational use of this insecticide and its compatibility with parasitoids. the experiment was in a completely randomized design. The treatments were the doses of 0.
Thaumastocoris peregrinus (Hemiptera: Thaumastocoridae), the eucalyptus bronze bug, is among the many species of insect pests that affect commercial eucalyptus forests in Brazil. T. peregrinus reduces the photosynthetic capacity of trees and, in some cases, can lead to the complete death of plants. The objective of this research was to evaluate the potential of medium spatial resolution images, available for free, in the mapping and prediction of attacks caused by T. peregrinus in eucalyptus plantations in Brazil, using Partial Least Squares Discriminant Analysis (PLS-DA). The PLS-DA regression model selected three main components, with a cross-validation error rate of 0.245 for the prediction and mapping of stands attacked by T. peregrinus. The important bands were selected from the PLS-DA model, using variable importance in the projection (VIP). The VIP bands predicted healthy and Palavras-chave: Análise discriminante dos mínimos quadrados parciais; Análise multivariada; Insetos-praga; Imagens de média resolução.
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