This review focuses on individual effects of major global change factors, such as elevated CO 2 , O 3 , UV light and temperature, on plant secondary chemistry. These secondary metabolites are well-known for their role in plant defense against insect herbivory. Global change effects on secondary chemicals appear to be plant species-specific and dependent on the chemical type. Even though plant chemical responses induced by these factors are highly variable, there seems to be some specificity in the response to different environmental stressors. For example, even though the production of phenolic compounds is enhanced by both elevated CO 2 and UV light levels, the latter appears to primarily increase the concentrations of flavonoids. Likewise, specific phenolic metabolites seem to be induced by O 3 but not by other factors, and an increase in volatile organic compounds has been particularly detected under elevated temperature. More information is needed regarding how global change factors influence inducibility of plant chemical defenses as well as how their indirect and direct effects impact insect performance and behavior, herbivory rates and pathogen attack. This knowledge is crucial to better understand how plants and their associated natural enemies will be affected in future changing environments. Climate change has been defined as "any change in climate over time, whether due to natural variability or as a result of human activity" (Intergovernmental Panel on Climate Change, IPCC 2007). However, this term is usually used in the context of global changes resulting from anthropogenic actions. Regardless of subtle differences in the usage of this term, there is a general consensus that current changes in climatic factors are primarily due to human-driven practices such as burning of fossil fuels and deforestation. These activities release significant amounts carbon into the atmosphere, which have caused a dramatic increase in carbon dioxide (CO 2 ) concentrations during the past 60 years. The IPCC has repeatedly reported that augmented emissions of greenhouse gases into the atmosphere (mainly elevated CO 2 followed by methane and ozone) are the major cause of climatic changes observed today. These changes include global warming, precipitation fluctuations, rising sea levels and other "extreme climatic events". Despite the amount of information that exists on global climate change, little is known regarding how these changes may affect natural ecosystems, particularly interactions among living organisms.Interactions of plants and insects are of major importance in most natural ecosystems since these two groups of organisms are extremely diverse and comprise almost 50% of all identified species on earth (Price 1997). The phytochemical coevolution theory suggests that secondary metabolites are likely the most important mediators of plant-insect interactions (Ehrlich and Raven 1964; Berenbaum 1983 Berenbaum , 1995 Cornell and Hawkins 2003). According to this theory, both plants and insect herbivores gene...

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The idea that addiction occurs when the brain is not able to differentiate whether specific reward circuits were triggered by adaptive natural rewards or falsely activated by addictive drugs exist in several models of drug addiction. The suitability of crayfish (Orconectes rusticus) for drug addiction research arises from developmental variation of growth, life span, reproduction, behavior and some quantitative traits, especially among isogenic mates reared in the same environment. This broad spectrum of traits makes it easier to analyze the effect of mammalian drugs of abuse in shaping behavioral phenotype. Moreover, the broad behavioral repertoire allows the investigation of self-reinforcing circuitries involving appetitive and exploratory motor behavior, while the step-wise alteration of the phenotype by metamorphosis allows accurate longitudinal analysis of different behavioral states. This paper reviews a series of recent experimental findings that evidence the suitability of crayfish as an invertebrate model system for the study of drug addiction. Results from these studies reveal that unconditioned exposure to mammalian drugs of abuse produces a variety of stereotyped behaviors. Moreover, if presented in the context of novelty, drugs directly stimulate exploration and appetitive motor patterns along with molecular processes for drug conditioned reward. Findings from these studies indicate the existence of drug sensitive circuitry in crayfish that facilitates exploratory behavior and appetitive motor patterns via increased incentive salience of environmental stimuli or by increasing exploratory motor patterns. This work demonstrates the potential of crayfish as a model system for research into the neural mechanisms of addiction, by contributing an evolutionary, comparative context to our understanding of natural reward as an important life-sustaining process.

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