Hypsipyla grandella. [Distribution map].

A new distribution map is provided for Hypsipyla grandella (Zeller). Lepidoptera: Pyralidae. Hosts: Spanish cedar (Cedrela odorata), mahogany (Swietenia macrophylla), American mahogany (S. mahagoni), African mahogany (Khaya senegalensis). Information is given on the geographical distribution in North America (Belize, Costa Rica, Cuba, Dominica, El Salvador, Grenada, Guadeloupe, Guatemala, Haiti, Honduras, Jamaica, Martinique, Mexico, Panama, Puerto Rico, Saint Lucia, Saint Vincent and the Grenadines, Trinidad and Tobago, United States, Florida), South America (Argentina, Bolivia, Brazil, Acre, Amapa, Amazones, Distrito Federal, Mato Grosso, Minas Gerais, Para, Rio Grande do Sul, Rondonia, Roraima, Santa Catarina, Colombia, Ecuador, French Guiana, Guyana, Paraguay, Peru, Suriname, Uruguay, Venezuela).

Leaf-cutting ant (Atta laevigata Smith) in an African mahogany plantation in Minas Gerais state, Brazil

Khaya grandifoliola C. DC. (Meliaceae), known as African mahogany, is used in the establishment of commercial plantations for high-value timber production. This work aims to report the first occurrence of the genus Atta in a commercial plantation of this species. An ant nest mound with 105 m2 of loose soil and five active ant holes were observed. Leaves cut into crescent shaped sections and pieces of young branches were found near these holes, in addition to trees with the apical part of their crown partially defoliated. The collected specimens were identified as Atta laevigata Smith (Hymenoptera: Formicidae: Attini), locally known as the glass-head leaf-cutting ant.

Numerical Modeling of Microfluid Dynamics in Xylem Vessels of Khaya grandifoliola

Computational fluid dynamic (CFD) can be used to quantify the internal flow variables of xylem conducting vessels. This study aims to analyze through numerical simulations the xylem water ascent of African mahogany (Khaya grandifoliola) cultivated under different irrigation regimes. We determined a geometric model, defined through the variability of the anatomical structures of the species, observing characteristics of the xylem vessels such as diameter, length, number of pits, and average surface area of the pits. Then we applied numerical simulation through an Eulerian mathematical model with the discretization of volumes via CFD. Compared to other models, we observed that numerical simulation using CFD represented the xylem microstructures in a greater level of detail, contributing to the understanding of the flow of xylem vessels and the interference of its various structures. Analyzing the micrographs, we observed the non-irrigated vessels had a higher number of pits in the secondary wall thickening when compared to the irrigated treatments. This trend influenced the variability of the radial flow of the xylem vessels, causing greater fluid movement in this region and decreasing the influence of the smooth part of the wall, resulting in a lower total resistance of these vessels.

Ultrasound to estimate the physical-mechanical properties of tropical wood species grown in an agroforestry system

The great diversity of tropical wood species makes it difficult to obtain information about their technological properties. The present work employed ultrasound to estimate the physical and mechanical properties of four wood species: African mahogany (Khaya senegalensis), ‘freijó’ (Cordia goeldiana), ‘paricá’ (Schizolobium amazonicum), and teak (Tectona grandis). Nineteen-year-old adult trees were selected and harvested from an agroforestry system (AFS) located in the Brazilian Amazon. From the harvested trees, 1.5 m logs were sawn and test specimens were obtained for physical-mechanical assays. The ultrasound propagation speed (V 0) and the dynamic modulus of elasticity (E d ) were obtained from applying ultrasound longitudinally in wood samples. Values of V 0 decreased from the lightest wood (paricá) to the heaviest (African mahogany), and E d presented the opposite behavior. For the physical properties, the coefficient of determination (R 2) ranged from 12 to 35% and the best linear regression models were fitted for the basic density, having V 0 and E d as independent variables. For the mechanical properties, the values of R 2 varied from 18 to 63% and higher correlations were found between parallel-to-grain compression strength and E d , and rigidity, static bending and Ed. Ultrasound presented the potential to estimate the properties of tropical wood species from the ASF.

Variações microclimáticas e edáficas em sistemas silvipastoris no município de Belterra, Pará

The objective of this work was to evaluate microclimatic and edaphic variations in silvopastoral systems, a system in which forest, forage species and animals that graze in consortium are integrated for production. The research was conducted at Fazenda Boa Safra located in the municipality of Belterra. The data were collected in a timely manner in October 2016 in two environments: four forage areas and four arboreal areas with the species: Andiroba (Carapa guianensis Aubl), African Mahogany (Khaya ivorensis A. Chev.), Teak (Tectona grandis L. f.) and Cumaru (Dipteryx odorata Willd.). The variables studied were temperature, soil moisture, litter stock and canopy cover. The results indicate that coumaru is the species that offers better thermal comfort compared to other species, while andiroba stood out in the best litter supply. The role of vegetation cover promoted by trees in the silvopastoral system is highlighted, promoting a better surface temperature of the soil (2 cm deep) in relation to pasture.

The Formation of Interlocked Grain in African Mahogany (Khaya spp.) Analyzed by X-Ray Computed Microtomography

Interlocked grain occurs when the orientation of xylem fibers oscillates, alternating between left- and right-handed spirals in successive wood layers. The cellular mechanisms giving rise to interlocked grain, thought to involve the slow rotation of fusiform initials within the vascular cambium, remain unclear. We suggest that observations of wood structure at the cellular level, but over large areas, might reveal these mechanisms. We assayed timber from several commercially-important tropical angiosperms from the genus Khaya (African mahogany) that exhibit interlocked grain using X-ray computed microtomography followed by orthogonal slicing and image processing in ImageJ. Reconstructed tangential longitudinal sections were processed with the ImageJ DIRECTIONALITY plug-in to directly measure fiber orientation, and showed grain deviations of more than 10o from vertical in both left- and right-handed directions. Grain changed at locally constant rates, separated by locations where the direction of grain change sharply reversed. Image thresholding and segmentation conducted on reconstructed cross sections allowed the identification of vessels and measurement of their location, with vessel orientations then calculated in Matlab and, independently, in recalculated tangential longitudinal sections with the DIRECTIONALITY plug-in. Vessel orientations varied more than fiber orientations, and on average deviated further from vertical than fibers at the locations where the direction of grain change reversed. Moreover, the reversal location for vessels was shifted ~ 400 μm towards the pith compared to the fibers, despite both cell types arising from the same fusiform initials within the vascular cambium. We propose a simple model to explain these distinct grain patterns. Were an auxin signal to control both the reorientation of cambial initials, as well as coordinating the end-on-end differentiation and linkage of xylem vessel elements, then it would be possible for fibers and vessels to run at subtly different angles, and to show different grain reversal locations.