EFFECTS OF TEMPERATURE ELEVATION ON THE POPULATION-DYNAMICS OF THE UPLAND HEATHER PSYLLID STROPHINGIA-ERICAE (CURTIS) (HOMOPTERA, PSYLLOIDEA)

1 Cloches permeable to gas and water were used to simulate the effect of climate warming on upland populations of the heather psyllid Stroph ingia ericae at Moor House National Nature Reserve in the North Pennin es, UK. 2 The cloches produced an average warming of about 1 degrees C in the heather canopy over a period of one year. 3 The density of S. ericae increased markedly in cloches within a few months of erection. 4 Species composition and numbers of potential predators were similar inside cloches and in control plots. 5 In the two year life-cycle of S . ericae, the warming effect advanced the phenology from the second to third instar in the first winter, but in the second winter, fifth ins tar nymphs did not moult prematurely to adult. 6 The density of S. eri cae was higher on Calluna vulgaris at its boundary with Juncus squarro sus than in the pure C. vulgaris sward (in both cloched and control pl ots).