Simulating Banks Grass Mite (Acari: Tetranychidae) Population Dynamics as a Subsystem of a Crop Canopy-Microenvironment Model

Abstract

The population dynamics of the Banks grass mite, Oligonychus pratensis (Banks), were described, using a distribution delay model (MitMod). MitMod was linked to a comprehensive plant-microenvironment model (Cupid). Leaf temperatures throughout the canopy are calculated by Cupid and are used by MitMod in the calculation of spider mite developmental rates and fecundity. In turn, spider mite densities alter parameters in Cupid and therefore exert an influence on plant-microenvironmental variables, Simulated crop water stress, manifested by stomatal closure, caused rapid Banks grass mite population growth, primarily through enhanced canopy and soil surface temperatures. Conversely, irrigation was found to suppress Banks grass mite densities primarily through reducing canopy and soil surface temperatures. Results of simulations suggest that, in semi-arid, hot regions, spacial and temporal variation in canopy microenvironments can play an important role in determining where and when spider mite outbreaks will occur.