Mortality estimation of seedlings and sampling subterranean termites in Eucalyptus plantations

Abstract

Subterranean termites are pests of all stages of the plant development in cultivated Eucalyptus in Brazil. Programs of integrated pest management (IPM) aims to avoid losses by termites and reduction on insecticides use, resulting in economic and environmental benefits. These programs require the quantification of damage and knowledge on the spatial distribution of these organisms. This study was conducted with two species of termites, both of economic importance, Syntermes molestus which damage seedling eucalyptus stage and Heterotermes tenuis which damage bark and trunk of mature trees. This study was conducted in seven commercial farms in a region originally of Mata Atlântica in Minas Gerais State, Brazil. In the first study, eucalyptus mortality was correlated with foraging holes of S. molestus, during six months after implantation, with zero inflated beta-binomial probability model. In the second work, spatial distribution of S. molestus and H. tenuis was studied, through the determination of assemblages between the two species related to altitude and vegetation factors, using the method of classification and spatial analysis (CASA). The best fitting model ignores the zero-inflation and despite the model uncertainty, the probabilistic beta-binomial model approach allows to predict the increase of seedlings deaths versus the increase of S. molestus foraging holes. The CASA method reveals five termites assemblages between S. molestus and H. tenuis, which was mapped and compared to the factors. This biological information allowed to propose a sampling plan for these termites.