Climate change and extreme weather events affect plants and animals and the direct impact of anthropogenic climate change has been documented extensively over the past years. In this review, I address the main consequences of elevated CO 2 and O 3 concentrations, elevated temperature and changes in rainfall patterns on the interactions between insects and their host plants. Because of their tight relationship with host plants, insect herbivores are expected to suffer direct and indirect effects of climate change through the changes experienced by their host plants, with consequences to population dynamics, community structure and ecosystem functioning.
Introducti onClimate change and extreme weather events affect plants and animals and the direct impact of anthropogenic climate change has been documented on every continent, in every ocean, and in most major taxonomic groups (Parmesan 2006 and references therein). As a consequence of recent human activities and its effects on global climate, plants will face new environmental conditions in the near future, such as elevated CO 2 and O 3 concentrations, elevated temperature and UV radiation, and changes in rainfall patterns over the seasons. Insects represent almost half of the biodiversity so far described (Speight et al 1999) and are central pieces on ecosystem structure and function (Crawley 1983). Because of their tight relationship with host plants, insect herbivores are expected to suffer direct and indirect effects of climate change through the changes experienced by their host plants.Global climatic changes are expected to impact insect-plant interactions in several ways. They might affect insects directly, through changes in physiology, behavior and life history parameters, as well as indirectly, through changes experienced by host plants in their morphology (Barnes et al 1988 (Gifford et al 1996, Yadugiri 2010) and patterns of richness, diversity and abundance (Thuiller et al 2005, Kazakis et al 2007. Insects play important roles in ecosystem services, acting as herbivores, pollinators, predators and parasitoids, and changes in their abundance and diversity have the potential to alter the services they provide (Hillstrom & Lindroth 2008). The number of studies reporting climate change effects on insects has rapidly increased during the past 20 years. A keyword search for "climate change" and "insects" in the Science Citation Index Expanded (1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010) resulted in almost 500 references, with a sharp increase over the past ive years (277 studies from 2006 to 2010, compared with 102 references from 2001 to 2005). As a result, a great body of literature has accumulated and several other authors reviewed the topic, both qualitatively (e.g., Watt et al 1995, Lindroth 1996, Bezemer & Jones 1998, Parmesan 2006, Tylianakis et al 2008 and quantitatively, using meta-analytical techniques (e.g., Zvereva & Kozlov 2006, Stiling & Cornelissen 2007, Wu et...