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 The replacement of natural grassland by cultivated areas might favor the increase in abundance of some root-feeding species such as the white grubs, which may become a constraint for field crop production. This research aimed to assay the population density and geographical distribution of white grubs pest and other species in natural grassland and cultivated areas throughout the Brazilian Pampa biome. White grubs were sampled in 18 locations in both landscape use types and identified. Population density (number of larvae m-2) was calculated for each recorded species and sorted within two groups (pest species and other species), compared between natural grasslands and cultivated areas, as well as among locations. A dendrogram to evaluate species similarity among locations was built based on combined data obtained from both landscape use types throughout the region. In total, 31 species were found in the Brazilian Pampa, and four of them are considered as crop pests: Diloboderus abderus (Sturm, 1826), Euetheola humilis (Burmeister, 1847), Lyogenys fusca (Blanchard, 1830), and Phyllophaga triticophaga Morón & Salvadori, 1998. The average population density of pest species in cultivated areas was less than five larvae m-2, at most of locations. Some species had a wide geographical distribution (e.g. D. abderus and Cyclocephala modesta Burmeister), while other melolontids occurred at only one location. The knowledge of which white grub species are present in a field and its population densities assist farmers to take proper management decisions.

RESUMO Além de competirem com as culturas, as plantas daninhas podem servir de abrigo para artrópodes, em lavouras e áreas adjacentes. Objetivou-se estudar a ocorrência e flutuação populacional de insetos-praga e inimigos naturais associados a buva (Conyza spp.), em áreas de cultivo de soja. As espécies predominantes foram Schizaphis graminum, Taylorilygus apicalis, Empoasca spp. e Nysius simulans. Espécies que compreendem complexos importantes de pragas, incluindo percevejos e lagartas, são capazes de se desenvolver sobre plantas dessa espécie daninha. Dentre elas, prevaleceram os percevejos Edessa meditabunda, Dichelops spp., Piezodorus guildinii, Nezara viridula e Euschistus heros, e as lagartas Anticarsia gemmatalis, Spodoptera frugiperda, Spodoptera eridania, Chrysodeixis includens e Helicoverpa spp. Os inimigos naturais mais encontrados foram Orius spp., Eriopis connexa, Cycloneda sanuiinea e Chrysoperla spp. A análise de flutuação populacional indicou a ocorrência de percevejos sobre plantas de buva, sobretudo no período inicial do cultivo e após a maturação da soja. Já as lagartas utilizam esta planta como hospedeiro alternativo durante todo o ciclo da cultura, continuando após a maturação e colheita da soja. Para os inimigos naturais, a flutuação das espécies depende da ocorrência de insetos que lhes servem como fonte de alimento. Logo, é possível concluir que a buva é um importante hospedeiro alternativo de insetos-praga e seus inimigos naturais, em cultivo de soja.

ABSTRACT In addition to competing with crops, weeds can provide shelter for arthropods in cropping fields and adjacent areas. This study aimed to investigate the occurrence and population fluctuation of insect pests and their natural enemies associated with hairy fleabane (Conyza spp.), in soybean farming areas. The predominant species were Schizaphis graminum, Taylorilygus apicalis, Empoasca spp. and Nysius simulans. Species that comprise important pest complexes, including stink bugs and caterpillars, can develop on fleabane plants. Among them, the stink bugs Edessa meditabunda, Dichelops spp., Piezodorus guildinii, Nezara viridula and Euschistus heros, as well as the caterpillars Anticarsia gemmatalis, Spodoptera frugiperda, Spodoptera eridania, Chrysodeixis includens and Helicoverpa spp. have prevailed. The most common natural enemies were Orius spp., Eriopis connexa, Cycloneda sanuiinea and Chrysoperla spp. The population fluctuation analysis indicated that hairy fleabane mainly hosted stink bugs at the beginning of the crop cycle and after soybean maturation. The caterpillars, however, use this weed as an alternative host throughout the crop cycle, continuing after soybean maturation and harvesting. For natural enemies species, the population fluctuation depends on the occurrence of insects that serve as a food source for them. Thus, it is possible to conclude that hairy fleabane is an important alternative host for pest insects and their natural enemies in soybean crops.

Esta nota é o primeiro registro da infecção de larvas de Diloboderus abderus Sturm pelo fungoOphiocordyceps melolonthae na região subtropical do Brasil. A identificação foi possível graças è extração e sequenciamento do DNA do fungo que cobria o aparelho bucal, protórax, cutícula e aparelho digestivo (canal alimentar) das larvas. Amplificação, sequenciamento e comparação da região ITS com sequências voucher do GenBank foram realizados, mostrando 95% de similaridade com Ophiocordyceps melolonthae. O fungo é um entomopatógeno que ataca larvas Melolonthidae, tendo importância científica e econômica devido è necessidade de aumento do conhecimento sobre sua distribuição e de alternativas de controle biológico de corós.

This note is the first report on the infection of Diloboderus abderus Sturm (Coleoptera: Melolonthidae) larvae by the fungusOphiocordyceps melolonthae (Hypocreales: Ophiocordycipitaceae) in subtropical Brazil. Identification was made possible by extraction and sequencing of the fungal DNA that was covering the larvae’s mouthparts, prothorax, cuticle, and digestive tract (alimentary canal). Amplification, sequencing and comparison of the ITS region of the ribosomal DNA with voucher sequences of GenBank were performed and were 95% similar to Ophiocordyceps melolonthae. The fungus is an entomopathogen which attacks Melolonthidae larvae, having scientific and economic importance because of the need for increased knowledge on its distribution and on alternatives for biological control of white grubs.