the GlobalChangeBiology blog

The grapevine moth Lobesia botrana (Den. & Schiff.) (Lepidoptera: Tortricidae) is the principal native pest of grape in the Palearctic region. In the present study, we assessed prospectively the relative abundance of the moth in Europe and the Mediterranean Basin using linked physiologically‐based demographic models for grape and L. botrana . The model includes the effects of temperature, day‐length and fruit stage on moth development rates, survival and fecundity. Daily weather data for 1980–2010 were used to simulate the dynamics of grapevine and L. botrana in 4506 lattice cells across the region. Average grape yield and pupae per vine were used as metrics of favourability. The results were mapped using the grass Geographic Information System ( http://grass.osgeo.org ). The model predicts a wide distribution for L. botrana with highest populations in warmer regions in a wide band along latitude 40°N. The effects of climate warming on grapevine and L. botrana were explored usi...

Cotton with coevolving pests has been grown in India for more than 5000 years. Hybrid cotton was introduced in the 1970s with increases in fertilizer and in insecticide use against pink bollworm that caused outbreaks of bollworm. Hybrid Bt cotton, introduced in 2002 to control bollworm and other lepidopteran pests, is grown on more than 90 % of the cotton area. Despite initial declines, year 2013 insecticide use is at 2000 levels, yields plateaued nationally, and farmer suicides increased in some areas. Biological modeling of the pre-1970s cotton/pink bollworm system was used to examine the need for Bt cotton, conditions for its economic viability, and linkage to farmer suicides. Yields in rainfed cotton depend on timing, distribution, and quantity of monsoon rains. Pink bollworm causes damage in irrigated cotton, but not in rainfed cotton unless infested from irrigated fields. Use of Bt cotton seed and insecticide in rainfed cotton is questionable. Bt cotton may be economic in irrigat...