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

Abstract

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 7-10 • 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 18-37% 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 aphid-plant interactions in terms of aphid-induced changes to plant growth.

Exploiting physical defence traits for crop protection: leaf trichomes ofRubus idaeushave deterrent effects on spider mites but not aphids

“…The aphid abundances were fairly typical for this aphid species (e.g. Johnson et al , ), although particularly low values might have resulted from slow aphid development, reduced fecundity or high mortality on some genotypes. A recent field study indicated a positive association between aphid abundance and leaf trichome density (Graham et al , ), which might be considered surprising; elevated leaf trichome density frequently has a negative effect on the abundance of aphids feeding on other crop species (Webster et al , ; Khan et al , ), although sap‐feeding herbivores can be unaffected by leaf physical traits (Carmona et al , ).…”

Top-down control byHarmonia axyridismitigates the impact of elevated atmospheric CO2on a plant-aphid interaction

“…This is particularly true for crops grown under cover (e.g. glasshouse, polytunnel), which is an increasingly common practice for enhancing productivity (Wittwer & Castilla, ; Johnson et al ., , ), because natural enemies work more effectively in closed environments (McMenemy et al ., ). Even in noncovered agricultural crops, top‐down regulation of herbivore populations is both important and increasingly encouraged (Stiling & Cornelissen, ; Van Driesche, ).…”

“…Confining aphids on plants necessitated the use of potted plants in closed chambers, which might result in artificially high plant growth responses to CO 2 enrichment (Ainsworth et al ., ). Given, however, that >90% of raspberry production takes place in closed polytunnels that buffer environmental fluctuations (Johnson et al ., , ), this is perhaps a less relevant concern in this system because chambers have similar effects. Moreover, the use of large pots and potting media minimized restrictions to root growth and the potential for hypoxic conditions, as advocated by Passioura ().…”

Unpredicted impacts of insect endosymbionts on interactions between soil organisms, plants and aphids

“…This increase in resource demand has been linked to a compensatory increase in photosynthetic rate [28,29], which can alter the growth and physiology of the plant, potentially inducing an increase in the biomass of plants exposed to herbivory [30 -32]. Such increases in growth could redirect resources away from sink tissues [32] such as the stolons and into structural tissues such as stems, although this effect did not extend to a decline in tuber mass. Response of tuber mass to aphid feeding was detected only when clone identity and soil treatment were taken into account, but there was no discernible pattern to this variation and any explanation for these effects, for example, owing to clonal differences in feeding rate and manipulation of resource allocation, are speculative.…”