A predictive framework to assess response of invasive invertebrates to climate change: pest mite species of Australian grains

<p>Climate change is set to place enormous pressure on both biodiversity and agricultural production. Important vectors of agricultural damage, such as pest invertebrates, are likely to respond to climate change in different ways. Differing pest invertebrate responses in grain crops will translate to shifts in outbreak frequency and persistence of pests, changes to pest species assemblages, and alter biocontrol by natural enemies. Successful management will thus require predictions of how climate change will affect individual species in terms of distributions and abundance. Climate change predictions for species are often based on models that characterize distributions though species-environment relationships. However, there are important factors relating to the ecology and evolutionary biology of species that are not incorporated and will mediate climate change response. This thesis aims to establish a transferrable framework, employing multiple, complimentary lines of enquiry, to build on distribution models and understand how climate change may affect different crop pests.</p> <p>I focus on two important mite species groups, the blue oat mites (Penthaleus spp.) and the redlegged earth mite (Halotydeus destructor). These mite species are invasive, and so understanding how they have adapted since being introduced into Australia will help predict response to climate change in the future. The first part of this thesis applies environmental niche models to distribution data of the three cryptic Penthaleus species, to make preliminary assessments of response to climate change. These models found that the distributions of each species are governed by different climate variables, and that species assemblages are likely to shift under climate change. The remainder of the thesis builds on such models by applying a more integrated approach to assess climate change response of H. destructor. This species provides an ideal candidate to develop this framework as the biology and ecology is well understood, and its introduction and spread in Australia has been well documented.