ESTIMATIVAS DE ATAQUE E DA DIVERGÊNCIA MORFOMÉTRICA EM SUBPOPULAÇÕES DE Sirex noctilio FABRICIUS EM POVOAMENTOS DE Pinus taeda L.

Abstract

One of the main pests that affect Pinus spp. plantations is Sirex noctilio Fabricius (Hymenoptera: Siricidae). The pest, which has been identified across six continents, affects not only forest management planning but also causes economic losses. The general objective of this study is to develop a model to estimate the number of pine trees per hectare attacked by S. noctilio and to understand the genetic variability among these forest pest populations. The study was carried out in Pinus taeda stands belonging to the Reflorasul company, located in Palmas, Paraná State, Brazil. For the development of the mathematical model, sequential sampling, number of individuals in the plot, trap trees, average diameter at breast height (DBH), average height, average individual volume, plot volume, age, spacing, site, basal area of the plot, mean cross-sectional area, quadratic mean diameter, and the DBH stratified into three diameter classes were used as independent variables of the model. Of these, only sequential sampling and the number of individuals in the plot were selected to compose the model, defined as δ = β0 + β1AS + β2n + ε. To determine the genetic diversity of S. noctilio, four subpopulations (areas 1, 2, 3, and 4) were evaluated. Trap trees were installed in September 2017 and S. noctilio adults were collected in June 2018. After emergence, individuals were stored in 70% alcohol for subsequent assessment. The following characteristics were measured: wing, abdomen, and total length for both sexes, and ovipositor length in females. The grouping of subpopulations was carried out using the Tocher optimization method. In males, two distinct groups were formed regardless of the evaluated characteristic. When grouping was performed considering only females and both males and females together, distinct groups were identified depending on the characteristic analyzed, indicating that there is genetic divergence between the analyzed subpopulations.