Effect of elevated CO2 on the demography of a leaf-sucking mite feeding on bean

The effect of elevated CO2 on the demography of the arachnid species Tetranychus urticae feeding on Phaseolus vulgaris plants was analysed. This class of herbivores (Arachnida) and its feeding guild (cell content feeders) are under-represented in studies of the combined effects of herbivory and CO2. The growth of bean was strongly stimulated by elevated CO2. The number of leaves on lateral stems and of flowers increased but pod weight decreased. Leaf nitrogen content was 25% lower at elevated CO2 due to an increase in non-structural sugar concentration. Leaf water content was lower at elevated CO2 while leaf-specific mass and epidermis thickness were higher. Females of the mite raised at ambient or elevated CO2, but all fed with leaves grown at ambient CO2, had similar progenies. When females were raised on plants grown at elevated CO2, the numbers of their progeny were reduced by 34% and 49% in the first and second generation respectively. Later stages of development were more reduced in elevated CO2, suggesting that both fecundity and rate of development were affected. This study suggests that the abundance of T. urticae, and consequently the damage to the many crops it infests, might decrease in a future elevated-CO2 environment

Effets de l'augmentation du CO2 atmosphérique sur la physiologie et les paramètres de rendement du haricot

Effects of elevated CO2 on the physiology and yield parameters of bean. The effects of elevated CO2 on bean ( Phaseolus vulgaris) physiology were analysed in greenhouses at 350 mul/l and at 700 mul/l (i.e. twice the actual level). The photosynthesis of beans grown under high CO2 concentration increased (+73% until the 40th day after germination). At high concentration, leaf nitrogen content was 15% lower while the C/N ratio was 19% higher. Leaf soluble and unsoluble sugar contents increased (+49 and +64%, respectively). The CO2 doubling significantly increased leaf area by 36% and leaf mass by 57%. Two months after sowing, plants exposed to 700 mul/l produced pods with higher fresh and dry weights (+44 and +110%, respectively). The individual pod dry weight and length also were also higher (+100 and +10%) but the number of seeds per pod was reduced (-9%). The soluble sugar content increased by 41%. In summary, the results suggest that the CO2 doubling has an important effect on bean yield, particularly on the quantitative level, but the increase in the soluble sugar content was more important on the qualitative level

Agriculture and crop protection its global importance and relationship with climate change

Agricultural practice, which includes well-established systems of cropping, pasture and forestry, represents a continual and essential dependence on healthy arable land across the globe and requires safeguarding with sustainable fertilization and pest control measures. This natural resource system must be continually protected from deliberate and inadvertent damage, in order to provide a suitable source of current and future amenities for all inhabitants of the planet. In this respect, it is morally and ethically necessary that we strive to manage the productivity and well-being of agricultural land in a way that will fulfil the necessities of the present generations and do not compromise needs of the future generations (Bruntland et al. 2012)

Climate change impacts on plant canopy architecture: implications for pest and pathogen management

Climate change influences on pests and pathogens are mainly plant-mediated. Rising carbon dioxide and temperature and altered precipitation modifies plant growth and development with concomitant changes in canopy architecture, size, density, microclimate and the quantity of susceptible tissue. The modified host physiology and canopy microclimate at elevated carbon dioxide influences production, dispersal and survival of pathogen inoculum and feeding behaviour of insect pests. Elevated temperature accelerates plant growth and developmental rates to modify canopy architecture and pest and pathogen development. Altered precipitation affects canopy architecture through either drought or flooding stress with corresponding effects on pests and pathogens. But canopy-level interactions are largely ignored in epidemiology models used to project climate change impacts. Nevertheless, models based on rules of plant morphogenesis have been used to explore pest and pathogen dynamics and their trophic interactions under elevated carbon dioxide. The prospect of modifying canopy architecture for pest and disease management has also been raised. We offer a conceptual framework incorporating canopy characteristics in the traditional disease triangle concept to advance understanding of host-pathogen-environment interactions and explore how climate change may influence these interactions. From a review of recent literature we summarize interrelationships between canopy architecture of cultivated crops, pest and pathogen biology and climate change under four areas of research: (a) relationships between canopy architecture, microclimate and host-pathogen interaction; (b) effect of climate change related variables on canopy architecture; (c) development of pests and pathogens in modified canopy under climate change; and (d) pests and pathogen management under climate change