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 This study aims to report two species of Scolytinae that have been damaging Carya illinoinensis trees in southern Brazil. In two Brazilian municipalities, Guarapuava in Paraná State and Pantano Grande in the Rio Grande do Sul State, insects of the Scolytinae family were found damaging pecan trees. Infested tree samples were kept in the laboratory in glass tubes sealed with a voile tissue until the emergence of adults. After the adults’ emergence, the specimens were identified by their morphological characteristics and sent to a taxonomist specialized in Scolytinae family for identification. The species Xyleborus retusus was identified causing damages to pecan trees from Guarapuava while the species Xyleborus ferrugineus was identified in pecan trees from Pantano Grande. Trees injured by these insects displayed similar symptoms in both study areas. In Guarapuava and Pantano Grande, 13 and 10 trees, respectively, died due to stem lesions caused by Xyleborus spp. Thus, this study reports for Brazilian pecan growers the occurrence of Scolytinae species X. retusus and X. ferrugineus damaging C. illinoiensis plants in southern Brazil. It also emphasizes the importance of constant crop monitoring to minimize the risk of pest damage.

RESUMO A lagarta do cartucho Spodoptera frugiperda é uma das principais pragas do milho, pelos danos que ocasiona e pela dificuldade de controle com as lagartas abrigadas e protegidas no interior das folhas do cartucho. Objetivou-se avaliar a influência da água no cartucho de milho, em combinação com inseticidas e conjuntos de pulverização, sobre os danos causados por S. frugiperda e a produtividade de grãos. Os experimentos foram conduzidos em campo, sob duas épocas de cultivo, ambas com híbridos de milho-Bt, em esquema fatorial 2 × 2 × 5 + 1, testando presença ou ausência de água no cartucho, dois inseticidas e cinco conjuntos de pulverização (combinações de volumes de calda, tipos de bico, pressões e velocidade de aplicação), mais um controle sem água e inseticida. A presença de água no cartucho reduziu os danos de S. frugiperda nos estádios iniciais, especialmente nas plantas tratadas com o inseticida clorantraniliprole. Os conjuntos de aplicação com 200 L ha1/20,3 psi ou 250 L ha1/33,4 psi proporcionaram as maiores reduções no percentual de plantas atacadas e nas notas de dano, independentemente do inseticida. Portanto, a aplicação de inseticidas, quando há água no cartucho do milho procedente de irrigação, orvalho ou chuvas, melhora o controle de S. frugiperda em cultivos de milho, especialmente em milho-Bt.

ABSTRACT The fall armyworm Spodoptera frugiperda is among the main insect-pests on maize crops, due to its damaging potential and control issues related to the larval habit of concealing itself within the plant whorl. This study aimed to evaluate the effect of water in the maize whorl, combined with insecticides and spray sets, on the damage caused by S. frugiperda and the grain yield. The experiments were carried out under field conditions, at two cropping seasons, both with Bt-maize hybrids, in a 2 × 2 × 5 + 1 factorial scheme, testing the presence or absence of water inside the plant whorl, two insecticides and five spray sets (combinations of spray volumes, nozzle types, pressures and spraying speed), plus a control without water and insecticide. The presence of water inside the whorl reduced the damage caused by S. frugiperda during the early growth stages, especially in the plants sprayed with the insecticide chlorantraniliprole. The spray sets with 200 L ha1/20.3 psi or 250 L ha1/33.4 psi provided the highest reductions in the percentage of damaged plants and damage scores, regardless of the insecticide. Therefore, the spraying of insecticides, when there is water from irrigation, dew or rainfall inside the maize whorl, improves the control of S. frugiperda in maize crops, especially in Bt-maize.

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 O estudo objetivou avaliar a eficiência de inseticidas no controle de Thaumastocoris peregrinus em laboratório. Para tanto, 15 plantas de Eucalyptus dunnii receberam aplicações a campo de: imidacloprido - 78,8 (g/ha), tiametoxam - 37,5 (g/ha), lambda-cialotrina+tiametoxam - 21,2+25,8 (g/ha), lambda-cialotrina - 24,9 (g/ha), e somente água (testemunha). Para determinar a eficiência dos inseticidas, utilizou-se o teste de confinamento, onde folhas de E. dunnii foram pulverizadas uma única vez, e em seguida, coletadas em dois períodos distintos. Em laboratório, foram utilizadas oito folhas para ninfas e oito para adultos, por tratamento, individualizadas em placas de petri; cada repetição recebeu 10 exemplares da espécie. As avaliações da sobrevivência foram realizadas no segundo, quarto, vigésimo segundo e vigésimo quarto dias após a aplicação dos tratamentos (DAT). Conclui-se que os inseticidas testados, nas suas respectivas doses, apresentam eficiência de controle de ninfas e adultos de T. peregrinus.

ABSTRACT The study aimed to evaluate the control efficiency of insecticides on Thaumastocoris peregrinus in the laboratory conditions. Therefore, 15 plants of Eucalyptus dunnii received the follow field spray: imidacloprid (78.8g ai / ha), thiamethoxam (37.5g ai / ha), lambda-cyhalothrin + thiamethoxam (21.2 + 25.8g ai / ha), lambda-cyhalothrin (24.9g ai / ha), and the untreated control only water. To determine the insecticides efficiency, we used a containment test, with E. dunnii leaves sprayed and collected at two different times. In the laboratory was used eight reps of leaves to adult and eight to nymphs by treatment individually placed in petri dishes; each repetition received 10 insect specimens. Assessments of alive insects were carried out at second, fourth, twentieth, twenty-fourth days after spray treatment (DAT). We conclude that the insecticides tested, on respective rate, presented efficient control of T. peregrinus nymphs and adults.