The effect of apple cultivar on the distribution of the predatory mite Typhlodromus pyri was studied in an experimental orchard where spider mites occurred at negligible densities. Seven apple scab-resistant cultivars, showing some differences in their leaf morphology, were considered. In particular, their leaf blade was classified according to four levels of pubescence. The distribution of T. pyri along the shoots was also studied. In the first experimental year the colonization of different cultivars by T. pyri showed definite patterns, sometimes influenced by the occurrence of eriophyids. One year later, T. pyri abundance again showed some differences among cultivars in conditions of prey scarcity. In both years large phytoseiid populations were recorded on the cultivar N.Y. 18491, despite the low eriophyid occurrence, probably because of its highly pubescent leaf undersurfaces. In contrast, Prima and TSR 29T219, characterized by slightly pubescent leaf undersurfaces, supported low phytoseiid densities independently of prey availability.

The effect of apple cultivar on the distribution of Amblyseius andersoni was studied in an experimental orchard where tetranychids were virtually absent and eriophyids reached low to moderate populations. Seven apple scab-resistant cultivars, showing some differences in their leaf morphology, were compared. Each cultivar was grafted onto three different rootstocks inducing increasing vigor. The intraplant distribution of A. andersoni was also studied by monitoring predator densities on basal and apical leaves. In the first year, the colonization of different cultivars by A. andersoni showed definite patterns, sometimes associated with the abundance of the eriophyid Aculus schlechtendali. In the second experimental season, eriophyids reached negligible levels and the effect of cultivar on A. andersoni abundance was less clear. Florina and N.Y. 18 491 cultivars were colonized in both years by relatively high phytoseiid numbers, while TSR 29T219 and Priscilla showed low populations in at least one season. The results observed on the remaining cultivars were intermediate or indefinite. The role of leaf pubescence on phytoseiid colonization is discussed.

Plant-insect interaction governs the dynamics of insect populations with respect to their interrelation with the environment. The objective of the present study was to identify the influence of antecedent crops, species and diameters of wild plants on the quiescent population of phytophagous stink bugs. The experiment was conducted in the months of June and July in Parada Link, municipality of Santa Maria, Rio Grande do Sul state, Brazil in two fields under crops of rice and soybean. In the off season, alternative host wild plants such as Andropogon bicornis, Andropogon lateralis, and Erianthus angustifolius with 10, 20, 30 and 40 cm in diameter were selected. Six wild plants were sampled for each crop, species, and diameter, totaling 144 experimental units. The stink bug species were identified and quantified. Soybean and rice previous cultivation, as well as the species and diameter of the wild plant, influence the quiescent population of Dichelops furcatus, Edessa meditabunda, E. rufomarginata, Euchistus heros, Piezodorus guildinii, and Tibraca limbativentris phytophagous stink bugs. The host plants A. bicornis, A. lateralis, and E. angustifolius were utilized for the maintenance of the populations of phytophagous stink bugs in the off-season periods. Soybean cultivation in floodplain areas has a negative impact on the quiescent population of T. limbativentris. RESUMO: A interação inseto-planta é o que rege a dinâmica de populações de insetos em interrelação com o ambiente. O trabalho teve por objetivo identificar a influência

Contribuição dos autores: Eduardo Engel realizou o experimento, a análise de dados, a revisão bibliográfica, a escrita científica e a apresentação dos resultados; Maurício Paulo Batistella Pasini contribuiu com a escrita científica, a análise de dados, a apresentação dos resultados e a revisão gramatical; Daniele Caroline Hörz Engel realizou o experimento, a revisão bibliográfica, a revisão ortográfica e a apresentação dos resultados. Fontes de financiamento: Não houve fonte de financiamento. Conflito de interesse: Os autores declaram não haver conflito de interesse.

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.

-The objective of this work was to select semivariogram models to estimate the population density of fig fly (Zaprionus indianus; Diptera: Drosophilidae) throughout the year, using ordinary kriging. Nineteen monitoring sites were demarcated in an area of 8,200 m 2 , cropped with six fruit tree species: persimmon, citrus, fig, guava, apple, and peach. During a 24 month period, 106 weekly evaluations were done in these sites. The average number of adult fig flies captured weekly per trap, during each month, was subjected to the circular, spherical, pentaspherical, exponential, Gaussian, rational quadratic, hole effect, K-Bessel, J-Bessel, and stable semivariogram models, using ordinary kriging interpolation. The models with the best fit were selected by cross-validation. Each data set (months) has a particular spatial dependence structure, which makes it necessary to define specific models of semivariograms in order to enhance the adjustment to the experimental semivariogram. Therefore, it was not possible to determine a standard semivariogram model; instead, six theoretical models were selected: circular, Gaussian, hole effect, K-Bessel, J-Bessel, and stable.Index terms: Zaprionus indianus, geostatistics, integrated pest management, monitoring, regionalized variables, spatial dependence. Modelos de semivariogramas para estimar a densidade populacional da mosca-do-figo ao longo do anoResumo -O objetivo deste trabalho foi selecionar modelos de semivariogramas para estimar a densidade populacional da mosca-do-figo (Zaprionus indianus; Diptera: Drosophilidae) ao longo do ano, com uso da krigagem ordinária. Dezenove locais de monitoramento foram demarcados em área de 8.200 m 2 , cultivada com seis espécies de frutíferas: caquizeiro, citros, figueira, goiabeira, macieira e pessegueiro. Durante um período de 24 meses, foram realizadas 106 avaliações semanais nesses locais. O número médio de moscas-do-figo capturadas semanalmente por armadilha, por mês, foi submetido aos modelos de semivariogramas circular, esférico, pentaesférico, exponencial, gaussiano, quadrático racional, seno cardinal, K-Bessel, J-Bessel e estável, por meio de interpolação por krigagem ordinária. Os modelos com melhor ajuste foram selecionados a partir da validação cruzada. Cada conjunto de dados (meses) tem uma estrutura de dependência espacial específica, o que torna necessário definir modelos específicos de semivariogramas para melhorar o ajuste ao semivariograma experimental. Portanto, não foi possível definir um modelo padrão de semivariograma; ao invés disso, seis modelos teóricos foram selecionados: circular, gaussiano, seno cardinal, K-Bessel, J-Bessel e estável.Termos para indexação: Zaprionus indianus, geoestatística, manejo integrado de pragas, monitoramento, variáveis regionalizadas, dependência espacial.

ABSTRACT. 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.

Stink bugs (Pentatomidae) are among the main entomological problems in the international farming. Their ability in using alternative plants (refuges) during the off-season is one of the reasons that led them to the status of key pests in several crops. Like other insect species, stink bugs are subject to atmospheric variations. Therefore, the objective of this experiment was to evaluate the abundance, the co-occurrence, and its variations according to the weather in the off-season. The work was conducted between 2014 and 2018, in the municipality of Cruz Alta, state of Rio Grande do Sul (RS), Brazil. Every year, refuges formed by Poaceae and located around the cropped area were evaluated in the second fortnight of June, corresponding to the beginning of the winter solstice. Atmospheric variables corresponding to the evaluation period were used to explain the variation in the populations. In short, our results demonstrated interannual variations in the population abundance of stink bugs in the evaluated refuges. We also found variations in the co-occurrence between species. Finally, we demonstrate the trend in the increase in these refuges in years with cold and dry off-seasons.