ABSTRACT
ABSTRACT The Cerambycidae Oncideres impluviata (Germar, 1823) is an important insect pest for Acacia mearnsii De Wild in Southern Brazil. The damage caused by their girdling behavior reduces tree productivity, specially in the early years of plant establishment, when girdling is performed on the main trunk of trees. Here, we used a fragment of the mtDNA COI gene to analyze the genetic diversity, population structure and demography of O. impluviata in Southern Brazil, as well as to present the first hypothesis of phylogenetic relationships among species of the genus Oncideres. Our results identified five distinct haplotypes among the populations of O. impluviata, with the most common haplotype identified as O.imp_COI_01. The phylogenetic inferences corroborated the monophyly of O. impluviata with maximum statistical support. In addition, the phylogeny recovered three main population strains that are largely congruent with the haplotype network, which includes two lineages that are found in different edaphic regions of Rio Grande do Sul (Serra do Sudeste and Encosta Inferior do Nordeste). This is the first molecular phylogenetic assessment of O. impluviata. Our findings provide insights into the evolution of a significant species for the Brazilian forestry sector, as well as new resources for planning of pest management strategies.
ABSTRACT
ABSTRACT This study aims to report the occurrence of Heilipus draco in seeds of Ocotea puberula, and to describe the main injuries caused to the seeds and the effects on germination, as well as the occurrence of parasitoid hymenopterans. To this end, fruits of seven trees were selected, in the extreme south of the Atlantic Forest, Brazil. Fruit collection was carried out weekly in the middle third of the canopy, forming lots, from the beginning of fruit formation until total dehiscence, for two years. In order to examine the damage caused by the granivorous insects inside the fruits, 100 fruits were sectioned taking into account the batch/year with the aid of a scalpel and analyzed using a binocular stereomicroscope. In the same way, 144 fruits from each lot/year were stored individually in transparent plates in order to verify the occurrence and identification of species of granivorous insects. The proof of the influence of the injury caused to the seeds by the granivorous insects was carried out by the germination test, with four replications of 25 seeds, comparing seeds with and without oviposition holes. The species H. draco was found to be associated with the fruits of O. puberula. The egg-layings are endophytic, carried out directly on the seed. Larval parasitism of Hymenoptera Bracon, Omeganastatus, Scambus and Triapsis was observed. It is concluded that the cycle from egg to adult takes place inside the seed of O. puberula, and the injuries caused by the larvae decrease germination.