Palm Red Mite Management with Soursop Seed Plant Residue Extracts

Raoiella indica Hirst, 1924 (Prostigmata: Tenuipalpidae), is one of the leading pest mites in palm and banana trees, however, there are few control methods available for this pest species. Therefore, this work aimed to evaluate the acaricidal effect of soursop seed extract (Annona muricata L.) on R. indica adults. The experiment was conducted in a completely randomized design using soursop seed extract with 7 replicates and 12 individuals of R. indica per replicate. The experimental units consisted of discs of coconut palm leaves (4 cm in diameter), with cotton moistened at the bottom of the Petri dish (10.0 × 1.2 cm) and around the disc to maintain turgor and prevent mites from escaping. The application was performed using an airbrush, connected to a calibrated compressor with a constant pressure of 1.3 psi and 1 mL of solution per repeat plate. The acaricidal effect was evaluated 24, 48, and 72 hours after spraying. Mortality data were corrected and submitted to Probit analysis (p ≤ 0.05) using the statistical program R, with the LC50 and LC90 calculated for the extract. At the maximum concentration (15%), the soursop seed extract showed mortality of 70% of individuals of R. indica, and the LC50 was 6.58%. It was concluded that the soursop seed extract showed acaricidal potential on R. indica in the laboratory.

Each Epiphyte on Its Branch: A Comparative Study between Different Phorophytes

Epiphytes are plants that use the mechanical support provided by a host tree, called phorophytes, without emitting haustorial structures. Constituting an important component of the flora, playing an important role in the maintenance of ecosystems, such as water and nutrient cycling, in addition to providing resources, sometimes unique, such as food and shelter, for the canopy fauna. However, the epiphytic flora may show high beta diversity, even when compared with different phorophytes, possibly as a response to the dendromorphological characteristics of the phorophyte. Thus, this work aims to: 1) compare whether the species richness of epiphytes differs in trees with different morphological characteristics, and 2) compare species composition among three tree species. For this, 10 individuals of three tree species were selected: Guaria guidonia, Ficus sp., and Roystonea oleracea. In each individual, the number of species (richness) of vascular epiphytes was recorded and obtained from the species composition. To test differences in richness values between the three trees, we used analysis of variance (ANOVA) followed by Tukey’s test. To understand whether the epiphyte community formed separate groups according to the tree species used, we used the available non-metric multidimensional scaling method (NMDS). Thirty-four species of epiphytes were found in the 30 phorophytes surveyed. The three tree species showed significantly different richness, with the highest found in Guarea guidonea and the lowest in Roystonea oleraceae. The NMDS showed that epiphytes group the three tree species into distinct groups, although Ficus sp individuals present a transitional community between the two other species. Thus, the results suggest that the differences in the richness and composition of the epiphytic flora of the different phorophytes are influenced by their distinct morphological characteristics.

What Do Seedlings Like? The Relationship between Seedling Richness and Abundance with Abiotic Factors

Natural regeneration is the interaction of natural processes to restore the forest ecosystem. Its dynamics are influenced by the intensity and extent of a series of abiotic and biotic factors, which may be intrinsic or extrinsic. Knowing the importance of establishing natural regeneration within forest ecosystems, this work aimed to evaluate whether litter depth and trail distance influenced seedling abundance and richness in a forest fragment undergoing natural restoration. The hypothesis tested in this research was that abiotic factors influence the natural regeneration of this forest since they are factors that are directly linked to seed germination and seedling establishment. 30 plots of 1 m2 were randomly analyzed within the forest located on the brown trail. A millimeter ruler was used to diagnose the litter depth and a measuring tape to measure the distance from the plot to the edge. In each plot the seedlings were morpho-specified and each morphospecies had the number of individuals counted. Linear regression tests were performed to assess the relationships between species richness and trail distance and litter depth. The same was done for species abundance. All results showed that there is no relationship pattern between any of the variables. Other factors also influence the regeneration of a forest, such as luminosity and seed bank. Furthermore, litter depth is related to the successional stage of the forest. It was concluded that the abiotic factors tested do not influence the regeneration of the study area.