RESUMEN

Co-occurrence a correlation profiles are driven by different factors (exogenous and endogenous) and drawing a profile of association between species based on co-occurrence, without assessing how these species vary in terms of ecological niche can lead to wrong conclusions. The objective was to determine the co-occurrence and correlation patterns of phytophagous insects in canola crop and to evaluate how these patterns varied according to the crop stage (phenology-biotic) and sowing times (agricultural practice-abiotic). We found that the patterns of co-occurrence and correlation between species were reflections of population variations due to the phenology and sowing times of canola. Variations in the multi-species abundance matrix were influenced by mean air temperature and accumulated rainfall. The main species associated with canola in southern Brazil, in terms of abundance, were P. xylostella, D. speciosa, and N. viridula. These species were mostly negatively associated. When evaluating their population variations, we found that they explore different temporal niches, whether in terms of phenology or sowing times. Finally, we demonstrate empirically that despite being important, association patterns based on co-occurrence and correlation should be interpreted in light of the understanding of patterns of niche exploitation and temporal variation of species.

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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.

RESUMEN

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.(AU)

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.(AU)

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RESUMEN

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.(AU)

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.(AU)

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Host plants are key factors in the survival of true bugs during unfavorable periods. The objective of this study was to evaluate the composition, diversity and abundance of pentatomid bugs in Saccharum angustifolium (Nees) Trin. (Poales: Poaceae). Plants were evaluated during the soybean and corn off--season for five years. A total of 250 plants were sampled, the true bug population was counted and used for statistical and faunistic analysis. We observed the occurrence of the species: Euschistus heros (F.), Dichelops furcatus (F.), Dichelops melacanthus (Dallas), Edessa meditabunda (F.), and Edessa ruformaginata (De Geer). Among the species, the highest population density was verified for E. meditabunda, E. heros, and D. furcatus. We also observed a direct effect of the clump diameter on the population density of E. heros, D. furcatus, and E. meditabunda. Finally, we conclude that S. angustifolium plants serve as adequate hibernacles for the survival of true bugs of economic importance during the soybean and corn off-season.(AU)

Plantas hospedeiras são fatores fundamentais na sobrevivência de percevejos durante períodos desfavoráveis. O objetivo deste trabalho foi avaliar a composição, diversidade e abundância de espécies de percevejos pentatomídeos ocorrentes em plantas de Saccharum angustifolium (Nees) Trin (Poales: Poaceae). As plantas foram avaliadas durante a entressafra de soja e milho por cinco anos. Foram amostradas 250 plantas, sendo a população de percevejos contabilizada e utilizada para a análise estatística e faunística. Observamos a ocorrência das espécies: Euschistus heros (F.), Dichelops furcatus (F.), Dichelops melacanthus (Dallas), Edessa meditabunda (F.) e Edessa ruformaginata (De Geer). Entre as espécies, foi verificada uma maior densidade populacional para E. meditabunda, E. heros e D. furcatus. Observamos, também, o efeito direto do diâmetro de touceira sobre a densidade populacional de E. heros, D. furcatus e E. meditabunda. Por fim, concluímos que plantas de S. angustifolium servem como hibernáculos adequados para a sobrevivência de percevejos de importância econômica durante a entressafra de soja e milho.(AU)

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RESUMEN

Host plants are key factors in the survival of true bugs during unfavorable periods. The objective of this study was to evaluate the composition, diversity and abundance of pentatomid bugs in Saccharum angustifolium (Nees) Trin. (Poales: Poaceae). Plants were evaluated during the soybean and corn off--season for five years. A total of 250 plants were sampled, the true bug population was counted and used for statistical and faunistic analysis. We observed the occurrence of the species: Euschistus heros (F.), Dichelops furcatus (F.), Dichelops melacanthus (Dallas), Edessa meditabunda (F.), and Edessa ruformaginata (De Geer). Among the species, the highest population density was verified for E. meditabunda, E. heros, and D. furcatus. We also observed a direct effect of the clump diameter on the population density of E. heros, D. furcatus, and E. meditabunda. Finally, we conclude that S. angustifolium plants serve as adequate hibernacles for the survival of true bugs of economic importance during the soybean and corn off-season.(AU)

Plantas hospedeiras são fatores fundamentais na sobrevivência de percevejos durante períodos desfavoráveis. O objetivo deste trabalho foi avaliar a composição, diversidade e abundância de espécies de percevejos pentatomídeos ocorrentes em plantas de Saccharum angustifolium (Nees) Trin (Poales: Poaceae). As plantas foram avaliadas durante a entressafra de soja e milho por cinco anos. Foram amostradas 250 plantas, sendo a população de percevejos contabilizada e utilizada para a análise estatística e faunística. Observamos a ocorrência das espécies: Euschistus heros (F.), Dichelops furcatus (F.), Dichelops melacanthus (Dallas), Edessa meditabunda (F.) e Edessa ruformaginata (De Geer). Entre as espécies, foi verificada uma maior densidade populacional para E. meditabunda, E. heros e D. furcatus. Observamos, também, o efeito direto do diâmetro de touceira sobre a densidade populacional de E. heros, D. furcatus e E. meditabunda. Por fim, concluímos que plantas de S. angustifolium servem como hibernáculos adequados para a sobrevivência de percevejos de importância econômica durante a entressafra de soja e milho.(AU)

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