Genetic diversity, phylogenetic and phylogeographic analyses of Oncideres impluviata (Germar, 1823) (Coleoptera: Cerambycidae) in Rio Grande do Sul state, Brazil

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.

Occurrence of Amblycerus species in Cordia trichotoma seeds and their influence on germination

ABSTRACT Forest species can have their seeds damaged by granivorous insects, especially by those in their larval stage. In this context, this study aims to report the occurrence of Amblycerus species in Cordia trichotoma seeds, to describe their main damage to seeds and effects on germination, as well as their associated hymenopteran parasitoids. Therefore, seven trees were selected in the municipality of Taquaruçu do Sul, RS, Brazil. Fruits were collected weekly from the medium third of the tree crown, from the beginning of their formation until total dehiscence. To examine the damage caused by granivorous insects within the fruits, 15 fruits from each tree were sectioned with a scalpel. Furthermore, 10 fruits from each tree were stored individually in clear plates to verify the occurrence and identification of granivorous insect species. Evidence of the damage caused to seeds was verified through the germination test by comparing preserved and damaged seeds, with four repetitions of 25 seeds each. The species Amblycerus longesuturalis and Amblycerus profaupar (Chrysomelidae: Bruchinae) were found associated with fruits of C. trichotoma. Female insects predominantly laid eggs on the superior part between the marcescent calyx and the fruit, and larvae perforated the fruit tegument to start consuming seed embryos and reserves. Bruquine larvae are parasitized by Hymenoptera of Bracon, Mirax, Omeganastatus and Triapsis genera. In conclusion, the germination of C. trichotoma seeds is significantly affected by emergence orifices caused by granivorous species.

First record of Heteropsylla caldwelli Burckhardt (Hemiptera: Psyllidae) from Brazil and its population dynamics on earpod tree in Rio Grande do Sul

Abstract Heteropsylla caldwelli Burckhardt (Psyllidae, Ciriacreminae) is reported for the first time from Brazil (States of Minas Gerais, Paraná, Rio Grande do Sul) from Enterolobium contortisiliquum (Vell.) Morong. The earpod tree, from Albizia edwallii (Hoehne) Barneby and J.W. Grimes and Senegalia polyphylla (DC.) Britton (Fabaceae, Mimosoideae), all previously unknown hosts. The population dynamics of the psyllid were investigated in a seven-year-old plantation of E. contortisiliquum in an abandoned open-pit coal mine in Candiota, Rio Grande do Sul during two years. The population showed peaks in spring and summer, correlating directly with the mean air temperature and the population size of microhymenoptera.