Protected raspberry production alters aphid-plant interactions but not aphid population size

1 Aphid population dynamics in crops are often driven by interactions with their host plants, which can be extensively influenced by environmental change. Protective environments (i.e. plastic tunnels) are now frequently used for soft fruit production, which may affect the localized climate and alter such interactions. This two year study on red raspberry (Rubus idaeus) addressed how protected environments affected two aphid species; the large raspberry aphid Amphorophora idaei (LRA) and the small raspberry aphid Aphis idaei (SRA). 2 Temperatures were higher (up to 710 degrees C) in tunnels compared with the field. Plants in tunnels grew approximately 1.4 cm/week faster and had lower (approximately 35%) foliar amino acid concentrations than plants in the field. 3 Aphids affected plant growth differently depending on growing environment; they promoted plant growth by 1837% in tunnels, although they had no such effect in the field. Aphids reduced total and essential amino acid concentrations, with SRA causing greatest reductions (approximately 40% and 33%, respectively). 4 Aphid population sizes were similar in both environments, although individual LRA were smaller in tunnels (30% smaller in 2007) compared with those in the field. We suggest that faster aphid development rates inside warmer tunnels were not realized as a result of the variable effects of the growing environment on amino acid composition. 5 We conclude that the increasing use of protected environments in crop production will not necessarily cause predictable increases in aphid populations, although it may alter aphidplant interactions in terms of aphid-induced changes to plant growth.