Introduction

To recognise and understand the environmental processes that lead to outbreaks of migrant pests, many environmental variables may need to be combined in a spatial context. Computer-based geographic information systems (GIS) make it possible to manipulate large spatially referenced data sets, including remotely sensed data on, for example, vegetation, rainfall and surface temperature. In this chapter, the extent to which these techniques have been applied to the ecology of migrant insect pests is discussed and ways in which they may be developed further are considered. The intention is not to provide technical information on the use of GIS and remote sensing, for which the reader is referred to standard texts (e.g. Curran, 1985; Burrough, 1986).

The use of GIS and remote sensing in entomology

GIS is the name given to the general techniques, and to specific computer packages, that can be used to register, store, manipulate and retrieve spatial data. The function of GIS is to integrate different types of spatial data. Spatial data are commonly held in computers in either vector or raster format and the relative advantages and disadvantages of each format are discussed by Burrough (1986). Vector data are a series of spatial coordinates defining points, lines and polygons that may be generated when maps are digitised, as well as specific point measurements, e.g. from meteorological stations, which are entered as tabular data. Raster data comprise a regular grid of cells, each having a particular value for a given variable. Satellite data are recorded in this format.