What was done
Grassland monoliths, removed from the Great Dun Fell in Cumbria, UK, containing eggs of the xylem-feeding insect Neophilaenus lineatus (spittlebug) were grown in glasshouses maintained at atmospheric CO2 concentrations of 350 and 600 ppm for two years to determine the long-term effects of elevated CO2 on this insect herbivore.

What was learned
During the course of the experiment, two generations of the xylem-feeding insect were produced; and in each case, elevated CO2 reduced the survival of nymphal stages by an average of 24%.  The authors suggest that this reduction in survival rate may have been caused by CO2-induced reductions in stomatal conductance and transpirational water loss, which may have reduced xylem nutrient-water availability, which is required to sustain this particular insect herbivore.

What it means
As the air's CO2 content continues to rise, this particular herbivore (spittlebug) likely will cause less tissue damage to plants of the species-poor grasslands of the Great Dun Fell in Cumbria, UK.