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Global warming impacts natural communities through effects on performance of individual species and through changes in the strength of interactions between them. While there is a body of evidence of the former, we lack experimental evidence on potential changes in interaction strengths. Knowledge about multispecies interactions is fundamental to understand the regulation of biodiversity and the impact of climate change on communities. This study investigated the effect of warming on a simplified community consisting of three species: rosy apple aphid Dysaphis plantaginea feeding on plantain, Plantago lanceolata, and a heterospecific neighbouring plant species, perennial ryegrass, Lolium perenne. The aphid does not feed on L. perenne. The experimental design consisted of monocultures and mixtures of L. perenne and P. lanceolata at three temperature levels. We did not find indication for indirect temperature effects on D. plantaginea through changes in leaf nitrogen or relative water content. However, experimental warming affected the life history traits of the aphid directly, in a non-linear manner. Aphids performed best at moderate warming, where they grew faster and had a shorter generation time. In spite of the increased population growth of the aphids under warming, the herbivory rates were not changed and consequently the plant-herbivore interaction was not altered under warming. This suggests reduced consumption rates at higher temperature. Also plant competition affected the aphids but through an interaction with temperature. We provide proof-of-concept that net interactions between plants and herbivores should not change under warming despite direct effects of warming on herbivores when plant-plant interaction are considered. Our study stresses the importance of indirect non-trophic interactions as an additional layer of complexity to improve our understanding of how trophic interactions will alter under climate change. [ABSTRACT FROM AUTHOR]

The green apple aphid ( Aphis pomi) and the spirea aphid ( Aphis spiraecola) are pests of apples in North America. Although management regimes exist to effectively control these pests, they differ significantly because of varying susceptibility of each species to common pesticides and differences in their life cycles. Therefore, accurate identification of the species present is essential for pest control. However, the identification process is complicated because of the morphological similarity between these two species. As a result, confusion between A. pomi and A. spiraecola often occurs. DNA barcoding has been proven to accurately identify species of Aphididae. A further study demonstrated that DNA barcodes could be used to accurately differentiate A. pomi and A. spiraecola. DNA barcoding represents an important step towards rapid identification of these pests as distinctions can be easily made between morphologically similar species as well as from eggs and immature individuals in addition to adults. However, samples must still be sent to specially equipped facilities for sequence analysis, which can take between several hours and days. Real-time PCR is emerging as a useful tool for more rapid pest identification. The purpose of this study was to develop a real-time PCR assay for differentiation of A.pomi from A. spiraecola based on DNA barcode sequences from the Barcode of Life Data System. This assay was designed on the portable SmartCycler II platform and can be used in field settings to differentiate these species quickly and accurately. It has the potential to be a valuable tool to improve pest management of A. pomi and A. spiraecola. [ABSTRACT FROM AUTHOR]