Geostatistics as a tool to study mite dispersion in physic nut plantations

Abstract

Spatial distribution studies in pest management identify the locations where pest attacks on crops are most severe, enabling us to understand and predict the movement of such pests. Studies on the spatial distribution of two mite species, however, are rather scarce. The mites Polyphagotarsonemus latus and Tetranychus bastosi are the major pests affecting physic nut plantations (Jatropha curcas). Therefore, the objective of this study was to measure the spatial distributions of P. latus and T. bastosi in the physic nut plantations. Mite densities were monitored over 2 years in two different plantations. Sample locations were georeferenced. The experimental data were analyzed using geostatistical analyses. The total mite density was found to be higher when only one species was present (T. bastosi). When both the mite species were found in the same plantation, their peak densities occurred at different times. These mites, however, exhibited uniform spatial distribution when found at extreme densities (low or high). However, the mites showed an aggregated distribution in intermediate densities. Mite spatial distribution models were isotropic. Mite colonization commenced at the periphery of the areas under study, whereas the high-density patches extended until they reached 30 m in diameter. This has not been reported for J. curcas plants before.

Spatial-temporal distribution of phytophagous and predatory mites in the canopy of Jatropha curcas L.

“…The number of mites was relatively low when compared to other studies performed in the state of Tocantins (Table 1) (SARMENTO et al, 2011;CRUZ et al, 2012;2013a;2013b;ROSADO et al, 2014;ROSADO et al, 2015a). However, a study performed during the same agricultural year (2011/2012) as the present study (SARAIVA et al, 2015) also observed a low occurrence of phytophagous and predatory mites associated with J. curcas.…”

“…However, a study performed during the same agricultural year (2011/2012) as the present study (SARAIVA et al, 2015) also observed a low occurrence of phytophagous and predatory mites associated with J. curcas. This indicates seasonal dynamics for both predatory and phytophagous mite populations of J. curcas (ROSADO et al, 2015a).…”

“…Considering the potential use of Jatropha curcas L. for biofuel production (ALONSO; LEZCANO, 2014), integrated management studies of pest arthropods associated with this crop are necessary for optimizing its production. For example, phytophagous mites are usually reported to be potential pests of J. curcas (SARMENTO et al, 2011;CRUZ et al, 2013a;LOFEGO et al, 2013;PEDRO-NETO et al, 2013;ROSADO et al, 2015a;2015b;SARAIVA et al, 2015). Predatory mites, especially those in the family Phytoseiidae, also colonize J. curcas plants and play a key role in limiting phytophage population (SARMENTO et al, 2011).…”

“…Seasonality may affect arthropod distribution and population density in the field (ZUNDEL et al, 2009), and climatic factors such as rainfall and temperature affect the population dynamics of phytophagous and predatory mites present in agricultural crops (PEDRO-NETO et al, 2010;CRUZ et al, 2013b;ROSADO et al, 2015a). Rainfall, relative humidity, and temperature are important explanatory mechanisms for abundance of the mite community colonizing J. curcas (CRUZ et al, 2013b).…”

Population density of Tibraca limbativentris on flood irrigated rice and alternative host plants

“…Populations of insect pests in crops can be estimated using interpolation procedures, which allow generating continuous surfaces through specific sampling units (Soares et al, 2008;Duarte et al, 2015). Among the interpolation methods, ordinary kriging is one of the most used (Sciarretta & Trematerra, 2014;Rosado et al, 2015). In it, theoretical semivariogram models are fit to the experimental ones, in order to find the best model -with the smallest errors -for each data set (Pasini et al, 2014).…”