Towards food web engineering. A study of genetic variability and experimental evolution with the predatory mite Amblyseius swirskii.

Abstract

This thesis is part of the project titled "Towards food web engineering: linking trait variability to ecosystem functioning" which has food web engineering (FWE) as its central point. FWE is an extension of biological pest control (BPC) that integrates ecology and evolution into crop management by combining experimental data with individual-based models (IBM). Therefore, the main objective is to generate experimental data that will feed, in the future, an IBM (Weaver). To this aim, this thesis covers the evaluation of genetic studies of traits relevant to BPC. To explore this, the model species was predatory mite Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae), widely used as a biological control agent against some of the most important and damaging groups of pests in protected crops. Specifically, the genetic variability and genetic correlations of several traits from two populations, one commercial and one wild, were evaluated. Furthermore, the hypothesis that commercial populations should have less genetic variability than wild populations due to the appearance of undesirable effects during mass breeding processes was confirmed. Subsequently, an experimental evolution experiment was carried out, where subpopulations of this species were exposed to two selection pressures, one abiotic (high temperature) and another biotic (presence of a top-predator), for several generations, in a full-cross experimental design that allowed to disentangle evolutionary responses driven by either, or both selection forces. It was also evaluated whether there was any adaptation or evolutionary cost to said exposure. The most remarkable result was an evolution towards smaller sizes only in the presence of both stressors.