ABSTRACT. Tibraca limbativentris is considered one of the main species of insect pests in irrigated rice. This species can be found in plants in the vegetative and reproductive stages. This study aimed to select semivariogram models to estimate rice stem bug population densities by ordinary kriging. Two fields were used to survey the T. limbativentris population in Oryza sativa. A grid of 30 x 30 m was drawn, which generated 143 and 385 sample units for the first and second fields, respectively. Seven evaluations of two hundred plants per sampling unit were performed during cultivation. From the insect counts, the results were input into circular, spherical, pentaspherical, exponential, Gaussian, rational quadratic, cardinal sine, K-Bessel, J-Bessel, and stable semivariogram models via ordinary kriging interpolation and the best model was selected via cross-validation. Each assessment had a particular spatial structure and semivariogram model that best fit the experimental data.

Abstract Kriging is a method that estimates values in places not sampled from different interpolators, therefore, widely used to predict the spatial distribution of organisms. However, the different interpolators may vary in performance depending on the organism under study or the area evaluated. The aimed study to compare the ordinary kriging and inverse of distance weighted interpolation methods, applied to the spatial distribution of population density of Tibraca limbativentris in irrigated rice. This study was carried out in Santa Maria, RS, Brazil, in two fields with areas of 1.3 ha and 6.2 ha, respectively. Seven evaluations of the population density of T. limbativentris were carried out, corresponding to the period from sowing to maturation. In these areas the adults of T. limbativentris were quantified and the sum used for the statistical and geostatistical analysis. The sample population of T. limbativentris was submitted to different semivariograms, which were selected through cross-validation. The sample population of T. limbativentris was submitted to different semivariograms, selected by means of cross-validation. Once selected, semivariograms were used in both tested interpolation methods. From the results it was concluded that the ordinary kriging interpolation method performed better in all evaluations performed in both areas. Therefore, we recommend its use for estimating the population density and spatial distribution of T. limbativentris in the irrigated rice throughout the crop phenology. Using appropriate interpolation methods, localized management can be used, reducing costs for controlling this pest and increasing the sustainability of the environment.

RESUMO O objetivo foi identificar a dispersão de Tibraca limbativentris (Hemiptera: Pentatomidae) em diferentes fases fenológicas do arroz irrigado. A pesquisa foi realizada em uma área de 20,12 ha, subdividida em quatro lavouras de 0,25 a 14,1 ha com a cultura de arroz irrigado, cultivadas sob as recomendações técnicas da cultura. Em cada lavoura, foi gerado um grid de amostragem de 30 × 30 m sendo cada ponto amostral correspondente a 1·m-2 (200 plantas), a amostragem realizada foi através de contagem direta. O número de adultos de T. limbativentris·m-2 foi submetido a análises descritivas e geoestatística. Tibraca limbativentris apresenta dispersão das bordaduras para o centro da área de cultivo de arroz irrigado. As maiores densidades populacionais foram estimadas na fase de antese e elongação.

ABSTRACT The objective was to identify the dispersion of Tibraca limbativentris (Hemiptera: Pentatomidae) in different phenological phases of irrigated rice. The research was carried out in an area of 20.12 ha, subdivided in four fields of 0.25 to 14.1 ha with the irrigated rice culture, grown under the technical recommendations of the culture. In each field, a sampling grid of 30 × 30 m was generated, with each sampling point corresponding to 1·m-2 (200 plants), sampling was through direct counting. The number of adults of T. limbativentris·m-2 was subjected to descriptive and geostatistical analyzes. Tibraca limbativentris presents border dispersion towards the center of the irrigated rice cultivation area. The highest population densities were estimated in the anthesis and elongation phase.

ABSTRACT. Identifying the behavior of natural enemies during the crop offseason is a key tool for integrated pest management. The objective of this work was to evaluate the population density of natural enemies of the plants Chloris distichophylla, Andropogon bicornis, and Erianthus angustifolium and to analyze the influence of the structural complexity of these plants on the present population. During the offseasons of 2014, 2015, and 2016, 150 plants of each species were evaluated and subdivided into different clump diameters. The species Lycosa spp., Eriops connexa, Cicloneda sanguinea, Coleomegilla quadrifasciata, Lebia concinna, and Harmonia axyridis were identified. A. bicornis was the plant with the highest population density, followed by C. distichophylla and E. angustifolium. Plants with greater structural complexities sheltered a higher population density of natural enemies.

Resumo: O objetivo deste trabalho foi avaliar a dinâmica populacional do percevejo-do-colmo (Tibraca limbativentris) no entorno e na área de cultivo de arroz irrigado por inundação, quantificar o fluxo populacional do percevejo entre lavouras e plantas hospedeiras, e determinar a influência da espécie, do diâmetro da planta e da distância da planta hospedeira da bordadura sobre a população do percevejo-do-colmo. O trabalho foi conduzido na safra 2012/2013 e na entressafra, com amostragem de plantas de arroz, Andropogom bicornis e A. lateralis em seis áreas de cultivo, para a contagem do número de insetos. A densidade populacional do percevejo-do-colmo em arroz irrigado e plantas hospedeiras alternativas apresenta dependência espacial e temporal. Nas áreas de cultivo, a densidade populacional do percevejo-do-colmo aumenta de acordo com a evolução dos estádios fenológicos do arroz, com as maiores densidades concentradas em regiões próximas às suas bordaduras. O diâmetro e a espécie da planta hospedeira influenciam a população do percevejo-do-colmo. Andropogon bicornis apresenta maiores densidades populacionais que A. lateralis e plantas com maiores diâmetros apresentam maiores densidades populacionais do percevejo-do-colmo. Durante a entressafra, a maior população do inseto em plantas hospedeiras se concentra até 45 m da bordadura, mas é capaz de se dispersar até 150 m.

Abstract: The objective of this work were to evaluate the population dynamics of the rice stem bug (Tibraca limbativentris) around and in flood irrigated rice cultivation area, to quantify the insect population flow between crops and host plants, and to determine the effect of the species, the diameter of the plant, and the distance of the host plant from the border on the rice stem bug population. The work was conducted in the 2012/2013 harvest and in the off-season, with sampling of rice, Andropogom bicornis, and Andropogon lateralis plants in six cultivated areas, in order to count the number of insects. The population density of the rice stem bug in irrigated rice and alternative host plants presents spatial and temporal dependence. In the cultivated areas, the population density of the rice stem bug increases according to the evolution of the rice phenological stages, with the highest densities concentrated in regions close to the crop borders. The diameter and species of the host plant affect the rice stem bug population. Andropogon bicornis plants have higher population densities than A. lateralis, and plants with larger diameters show higher population densities of the rice stem bug. In the off-season, the greatest population of the rice stem bug on host plants is concentrated up to 45 m from the crop border, but it can disperse until 150 m.

O conhecimento da entomofauna dos ecossistemas florestais tem sua importância no que se refere aos danos provocados pelos seus diferentes segmentos. Estudou-se a bioecologia do serrador Oncideres cervina (Coleoptera: Cerambycidae), em Ocotea puberula (Lauraceae), na região central do estado do Rio Grande do Sul, Brasil. Em 49 galhos cortados foram analisados a frequência de corte, o diâmetro de galhos no corte e secções, comprimento de galhos, frequência de incisões de postura, emergência de adultos, tamanho do orifício de saída, comprimento e volume da galeria larval desta espécie. O período de corte de galhos se estende de fevereiro a março e esta espécie se enquadra como cortadora de galhos grossos. O número de incisões de postura é variável, porém, a maior concentração é encontrada nas secções de 20 a 40 cm a partir do corte, com valor médio de 11 incisões. Duzentos adultos emergiram de 27 galhos, com pico de emergência na primeira quinzena de dezembro. Para completar o seu desenvolvimento, esta espécie requer menor volume de madeira se comparada a outras espécies de serrador.

The insect fauna knowledge of forest ecosystems have their importance in relation to damage caused by their different segments. The bioecology of the Oncideres cervina (Coleoptera: Cerambycidae) in Ocotea puberula (Lauraceae) was studied in the central region of Rio Grande do Sul state, Brazil. In 49 cut twigs were analyzed the cutoff frequency, the diameter of cut twigs and sections, twig length, posture incisions frequency, adult emergence, exit orifice size, length and volume of the larvae gallery of this species. The cut twigs period extends from February to March and this species is fit as thick cutter twigs. The incisions posture number is variable, but the highest concentration is found on sections 20 to 40 cm from the cut, with an average value of 11 incisions. Two hundred adults emerged from 27 twigs, with the most emergent on the first half of December. In order to complete its development, this species requires less wood volume if compared to other twig girdlers species.

Com o objetivo de determinar a eficiência de diferentes diâmetros de furos em garrafas PET na captura de moscas das frutas e seu efeito sobre o ataque de pragas em pomar de goiaba e caqui, desenvolveram-se dois experimentos no período de 31 de janeiro a 6 de março de 2012, em Santa Maria, Estado do Rio Grande do Sul, Brasil. Em delineamento de blocos ao acaso sob esquema fatorial, avaliou-se o número médio de adultos de Anastrepha fraterculus, Ceratitis capitata (Diptera: Tephitidae) e Zaprionus indianus (Diptera: Drosophilidae) emergidos de frutos em duas situações (no chão e sobre a planta) e o número de adultos capturados por armadilhas frasco caça mosca em duas condições iniciais de volume, ambas sob diferentes diâmetros de furo e em diferentes dias após a colocação do atrativo alimentar. Diâmetros de tamanho menor apresentaram maior captura de adultos de A. fraterculus, C. capitata e Z. indianus. O diâmetro de 1,0 cm apresentou maior eficiência na redução da emergência de adultos de Tephritidae, para Z. indianusos menores diâmetros, 0,6 e 0,8 cm, apresentaram as maiores eficiências sobre a emergência de adultos de frutos de caqui e goiaba.

Two experiments were conducted during the period from 31 January to 6 March 2012 in Santa Maria, Rio Grande do Sul State, Brazil to determine the efficiency of different hole diameters in PET trap bottles on pests in guava and persimmon orchards. In a randomised block design in a factorial scheme, we assessed the average number adults of Anastrepha fraterculus, Ceratitis capitata (Diptera: Tephitidae) and Zaprionus indianus (Diptera: Drosophilidae) infruits thatemerged in two situations (in the plant and on the soil); we also assessed the number of captured adults in trap bottlesunder two conditions, different hole diameters and different days after placement of the attractive solution. Smaller diameter sizescaptured more A. fraterculus, C. capitata and Z. indianusadults. The 1.0 cm diameter was the most efficient hole size in reducing the adult emergence of Tephritidae to Z. indianus, whereas the smallest diameter hole sizes, 0.6 and 0.8 cm, showed the highest efficiencies in controlling adult emergence in persimmon fruit and guava fruit.

São escassas as informações referentes à presença de pentatomídeos na amoreira-preta no Brasil (Rubus spp.). Este trabalho teve por objetivos de identificar as espécies de pentatomídeos associadas à amoreira-preta, realizar a análise faunística e determinar seus danos em frutos. O experimento foi conduzido em Santa Maria, Rio Grande do Sul, Brasil, em pomar de amoreira-preta. Semanalmente, foram realizadas avaliações visuais sobre amoras e amostragens por batimento para identificação dos pentatomídeos associados e caracterização de danos, realizadas em diferentes horários do dia. Foram determinadas cinco espécies de pentatomídeos associadas amoreira-preta: Piezodorus guildinii, Nezara viridula, Euschistus heros, Dichelops furcatus e Edessa meditabunda. Esses percevejos atacam as mini-drupas deixando-as com aspecto marrom escuro e enrugado.

Information concerning the presence of stink bugs in blackberry (Rubus spp.) in Brazil is sparse. This study aimed to identify the stink bug species associated with blackberry, to establish the daily dynamics and evaluate the fruits damage. The experiment was conducted in Santa Maria, Rio Grande do Sul State, Brazil, in blackberry orchard. Presence and evaluations of stink bugs were done weekly through visual and sweeping samplings at different day times. Five species of pentatomids were identified: Piezodorus guildinii, Nezara viridula, Euschistus heros, Dichelops furcatus and Edessa meditabunda. The bugs attack the drupelets producing a dark brown spot and wrinkled berries.

A mosca-do-figo (Zaprionus indianus) é uma das principais pragas da cultura do figo, no Brasil, sendo o seu monitoramento importante para a redução no uso de inseticidas químicos. Este estudo objetivou avaliar a eficiência de atrativos alimentares para o monitoramento de Z. indianus, em pomar de figo. O experimento foi instalado em pomar doméstico de figo (cv. Roxo de Valinhos), utilizando-se cinco tratamentos (suco de figo a 50%, melaço de cana a 7% e suco de uva a 30%, 40% e 50%), com cinco repetições, em delineamento inteiramente casualizado. Foram capturados 3.284 indivíduos adultos da mosca-do-figo (1.983 fêmeas e 1.301 machos), representando 42% do total de insetos e 62% dos drosofilídeos capturados. A proporção de machos e fêmeas foi similar em todas as soluções atrativas. A solução suco de figo a 50% foi eficiente na captura da mosca-do-figo, podendo ser recomendada para o seu monitoramento em pomares domésticos. A solução melaço de cana a 7%, embora eficiente, não apresentou regularidade na captura da mosca-do-figo, sendo indicada apenas para períodos inferiores a 28 dias. Nas concentrações testadas, o suco de uva não foi eficiente.

The fig fly (Zaprionus indianus) is one of the major fig pests in Brazil, being its monitoring important for reducing the use of chemical insecticides. This study aimed at evaluating the efficiency of attractive food for Z. indianus, in fig orchard. The experiment was installed in a domestic fig ('Roxo de Valinhos' cultivar) orchard, using five treatments (fig juice at 50%, sugarcane molasses at 7% and grape juice at 30%, 40% and 50%), with five replicates, in a completely randomized design. A total of 3,284 adult fig flies (1,983 female and 1,301 male) were captured, representing 42% of the total insects and 62% of the drosophilids captured. The proportion of males and females was similar for all attractive solutions. Fig juice at 50% was effective in capturing the fig fly, being recommended for its monitoring in domestic orchards. Sugarcane molasses at 7%, despite its effectiveness, did not present regularity in fig fly capturing, being only indicated for periods of less than 28 days. At the concentrations tested, the grape juice was not effective.