Figure 4 - available via license: Creative Commons Attribution 4.0 International
Content may be subject to copyright.
Relative deviation coefficient (RDC, in %) among maps of the Euschistus heros infestation obtained by the reference sampling grid (10 × 10 m) and others sizes of sampling grids during different reproductive phenological stages of the soybean crop, in Londrina, Paraná.
Source publication
Euschistus heros is one the most important pest insect in soybean fields in Brazil. Therefore, site-specific management applied for controlling E. heros can result in economic and environmental benefits. However, sampling protocols for assessing spatialtemporal variability of this soybean pest and, then, for guiding a more sustainable pest manageme...
Context in source publication
Context 1
... these soybean phonological stages the infestation of E. heros was > 3.5 individual per meter, being considered above of the economic threshold level established by pest integrated management in soybean fields in Brazil ( Bueno et al. 2013). These results were confirmed by the RDC data (Figure 4), in which smaller sampling grid sizes decreased the data deviation among maps, as well as high insect infestation (i.e., from R 5.4 to R 7 ) also led to greater similarity among maps (i.e., RDC < 0.20). Negative linear correlations were observed for both RDC versus average the E. heros infestation (-0.83; p< 0.05), and RDC versus CV values (-0.85; p < 0.05). ...
Citations
... Understanding the spatiotemporal dynamics of pest insects in crops provides important information that can be incorporated into integrated pest management programs [19][20][21][22]. The study of the spatiotemporal dynamics of insects using geostatistics can provide important information about the pattern of colonization, aggregation, and dispersion of pests in the field [20,[22][23][24][25]. This statistical tool uses a method that characterizes spatial variation by comparing similarities between distant and proximal points. ...
... This technique provides results that allow colonization maps to be produced, zoning the different densities and determining the pattern of spatial distribution of the insects in the field [20,25]. A sequence of these maps during crop development may indicate areas that demand greater attention for the observation of pest infestation over time. ...
... Some results obtained for B. tabaci adults and nymphs showed a weak degree of spatial dependence. This finding is characterized as a pure nugget effect (total absence of spatial dependence), probably due to the low infestation by adults and whitefly nymphs in each evaluation, making the presence of insects in geostatistical analyses imperceptible [25,35]. These results are a common finding in this type of study; other authors with experiments on the spatial distribution of Euschistus heros (Fabricius, 1798) (Hemiptera: Pentatomidae) in soybean have made similar observations [25,36]. ...
Spatiotemporal dynamics studies of crop pests enable the determination of the colonization pattern and dispersion of these insects in the landscape. Geostatistics is an efficient tool for these studies: to determine the spatial distribution pattern of the pest in the crops and to make maps that represent this situation. The aim of this study was to determine the spatiotemporal distribution of B. tabaci adults and nymphs in commercial soybean crops from planting to harvest using geostatistics. Infestation by adults and nymphs of B. tabaci started between 30 and 50 days after the emergence of the plants. The maximum population density of ten adults per plant and two nymphs per leaf was registered between 90 and 101 days after plant emergence. The colonization of soybean plants by B. tabaci may be divided into three stages: beginning infestation (at the outermost parts of the crop), whole area colonization, and dispersion colonization (when the whole crop area is infested). The density of adult insects was positively correlated with rainfall and relative humidity. Wind speed positively affected the dispersion of adult whiteflies. The distribution pattern of B. tabaci in the soybean crop was aggregated.
... The spatiotemporal dynamics of insects using geostatistics can provide important information about the pattern of colonization, aggregation, and dispersion of pests in the field (Pias et al., 2017;Galdino et al., 2017;Lima et al., 2018;Suekane et al., 2018;Martins et al., 2018;Felicio et al., 2019). This statistical tool uses a method that characterizes spatial variation by comparing similarities between distant and proximal points. ...
... This statistical tool uses a method that characterizes spatial variation by comparing similarities between distant and proximal points. This technique provides results that allow colonization maps to be produced, zoning the different densities, and determining the pattern of spatial distribution of the insects in the field (Pias et al., 2017;Lima et al., 2018). A sequence of these maps during crop development may indicate areas that demand greater attention to pest sampling and control in time and space (Sciarretta and Trematerra, 2014;Macfadyen et al., 2015;Martins et al., 2018). ...
... Some results obtained for B. tabaci adults and nymphs showed a weak degree of spatial dependence. This finding is characterized as a pure nugget effect (total absence of spatial dependence), probably due to the low infestation by adults and whitefly nymphs in each evaluation, making the in geostatistical analyses imperceptible (Reay-Jones et al., 2010;Pias et al., 2017). These results are a common finding in this type of study; other authors with experiments on the spatial distribution of Euschistus heros (Fabricius, 1798) (Hemiptera: Pentatomidae) in soybean have made similar observations (Pias et al., 2017;De Souza et al., 2018). ...
Studies on the spatiotemporal dynamics of crop pests enable the determination of their colonization pattern and dispersion in the landscape. Geostatistics is an efficient tool to determine the spatial distribution pattern of the pest in the crops and to visualize them in appropriate maps. Analysis of these maps across the crop developmental stages can be a helpful tool in precision agriculture programs. The aim of this study was to determine the spatiotemporal distribution of Bemisia tabaci whitefly adults and nymphs in commercial soybean crops from planting to harvest. Infestation by the whitefly adults and nymphs started between 30 and 50 days after plant emergence. The maximum population density of ten adults per plant and two nymphs per leaf occurred between 90 and 101 days after plant emergence. In Kriging maps, it was possible to observe the distribution pattern for both adults and nymphs. The colonization of soybean plants by B. tabaci may be divided into three stages: beginning infestation (at the outermost parts of the crop), whole area colonization, and dispersion colonization (when the whole crop area is infested). The density of adult insects was positively correlated with rainfall and relative humidity. Wind speed positively affected the dispersion of adult whiteflies. The distribution pattern of B. tabac i in the soybean crop was aggregated. Climatic factors, such as wind speed, increase the dispersion radius of the whitefly in the crop. Contribution to the field.
... Traditional techniques of Geostatistics by linear kriging have been applied in Agricultural Entomology to map the distribution of organisms in a space when the target variables of the study are insect density (insect counts) (Pazini et al., 2015a;Alves et al., 2016;Pias et al., 2017;Pasini et al., 2018). However, there are no studies for categorical data, such as the occurrence of pest insects in the immature or adult phase or the coexistence of these phases predominant in crop segments throughout the crop cycle. ...
The rice stem bug, Tibraca limbativentris Stal (Hem.: Pentatomidae), is one of the main insect pests in Brazilian rice crops. Knowledge of its spatiotemporal distribution can support the development of an effective sampling system and improve IPM strategies. This study aimed to map the spatiotemporal distribution of rice stem bug in flooded rice crop in Southern Brazil. Flooded rice crop was scouted for two seasons to estimate insect densities. Four occurrence categories were observed: no insect, only adults, only nymphs, and both phases. The relationship between phenological stages and insect categories was established. Interpolation (mapping)of occurrence categories of T. limbativentris was performed by multiquadric equations. In two seasons during the rice cycle, the results indicate that rice stem bug “adults” were the most abundant category until the mid-vegetative phase of the rice; “nymphs” were the most abundant from the end of vegetative phase; “adults + nymphs” occurred from the beginning of reproductive phase; there were no rice stem bugs in more than 66% of the area, as they were most concentrated near the edge of the crop. The information presented here provides further knowledge about T. limbativentris spatiotemporal dynamics that can be applied to improve IPM strategies, such as developing sampling plans and localized control measures at the edge of rice fields.
