Geostatistics applied to the study of the spatial distribution of insects and its use in integrated pest management

Abstract

Integrated Pest Management (IPM) programs based on the temporal variability of insect pests have been successfully implemented worldwide. These programs have been carried out by applying control strategies based on the existing knowledge about pest biology and population dynamics. However, systems based on temporal variability are insufficient to optimize plant protection and especially to reduce the environmental impact of area-wide control measures. This situation drove to the new concept of “site-specific IPM”. Currently, there are tools to implement large-scale studies (at a zonal and a regional level), allowing to describe and analyze the spatial distribution of insect populations via the management and analysis of large data sets (GIS, GPS, and geostatistics). Geostatistics measures the spatial fluctuations of the variables under study based on rigorous sampling, afterwards adjusting a semivariogram, interpolating and building maps of iso-lines with different levels of population densities. This has allowed to simplify forecasting and monitoring systems, determining both the location and the optimum number of samples to be taken on sites showed by iso-lines. In order to decide where control measurements should be applied, maps with geographical coordinates showing the spatial location of spots with high population density are used (regardless of the control strategy applied). Furthermore, these methods can be used to identify areas where, considering their special characteristics, selective large-scale control tactics, as mating disruption or the release of natural enemies could be applied.