10.4.1.5 Pests and diseases
Some studies (Rosenzweig et al., 2001; FAO, 2004c) agree that higher temperatures and longer growing seasons could result in increased pest populations in temperate regions of Asia. CO2 enrichment and changes in temperature may also affect ecology, the evolution of weed species over time and the competitiveness of C3 v. C4 weed species (Ziska, 2003). Warmer winter temperatures would reduce winter kill, favouring the increase of insect populations. Overall temperature increases may influence crop pathogen interactions by speeding up pathogen growth rates which increases reproductive generations per crop cycle, by decreasing pathogen mortality due to warmer winter temperatures, and by making the crop more vulnerable.
Climate change, as well as changing pest and disease patterns, will likely affect how food production systems perform in the future. This will have a direct influence on food security and poverty levels, particularly in countries with a high dependency on agriculture. In many cases, the impact will likely be felt directly by the rural poor, as they are often closely linked to direct food systems outcomes for their survival and are less able to substitute losses through food purchases. The urban poor are also likely to be affected negatively by an increase in food prices that may result from declining food production.