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Kerslake et al. (1998) grew five-year-old heather (Calluna vulgaris) plants that they collected from a Scottish moor within open-top chambers maintained at atmospheric CO2 concentrations of 350 and 600 ppm, where at two different times during the study, larvae of the destructive winter moth Operophtera brumata – whose outbreaks periodically cause extensive damage to heather moorland – were allowed to feed upon current-year shoots. Interestingly, feeding upon the high-CO2-grown foliage did not affect larval growth rates, development or final pupal weights; neither was moth survivorship significantly altered. Hence, the three researchers concluded that their study provided “no evidence that increasing atmospheric CO2 concentrations will affect the potential for outbreak of Operophtera brumata on this host.” What it did show, however, was a significant CO2-induced increase in heather water use efficiency.