1. Aphids represent a significant challenge to food production. The Rothamsted Insect Survey (RIS) runs a network of 12·2-m suction-traps throughout the year to collect migrating aphids. In 2014, the RIS celebrated its 50th anniversary. This paper marks that achievement with an extensive spatiotemporal analysis and the provision of the first British annotated checklist of aphids since 1964.2. Our main aim was to elucidate mechanisms that advance aphid phenology under climate change and explain these using life-history traits. We then highlight emerging pests using accumulation patterns.3. Linear and nonlinear mixed-effect models estimated the average rate of change per annum and effects of climate on annual counts, first and last flights and length of flight season since 1965. Two climate drivers were used: the accumulated day degrees above 16 °C (ADD16) indicated the potential for migration during the aphid season; the North Atlantic Oscillation (NAO) signalled the severity of the winter before migration took place.4. All 55 species studied had earlier first flight trends at rate of β = −0·611 ± SE 0·015 days year−1. Of these species, 49% had earlier last flights, but the average species effect appeared relatively stationary (β = −0·010 ± SE 0·022 days year−1). Most species (85%) showed increasing duration of their flight season (β = 0·336 ± SE 0·026 days year−1), even though only 54% increased their log annual count (β = 0·002 ± SE <0·001 year−1).5. The ADD16 and NAO were shown to drive patterns in aphid phenology in a spatiotemporal context. Early in the year when the first aphids were migrating, the effect of the winter NAO was highly significant. Further into the year, ADD16 was a strong predictor. Latitude had a near linear effect on first flights, whereas longitude produced a generally less-clear effect on all responses. Aphids that are anholocyclic (permanently parthenogenetic) or are monoecious (non-host-alternating) were advancing their phenology faster than those that were not.6. Climate drives phenology and traits help explain how this takes place biologically. Phenology and trait ecology are critical to understanding the threat posed by emerging pests such as Myzus persicae nicotianae and Aphis fabae cirsiiacanthoidis, as revealed by the species accumulation analysis.

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Genetic diversity is the determinant for pest species' success and vector competence. Understanding the ecological and evolutionary processes that determine the genetic diversity is fundamental to help identify the spatial scale at which pest populations are best managed. In the present study, we present the first comprehensive analysis of the genetic diversity and evolution of Rhopalosiphum padi, a major pest of cereals and a main vector of the barley yellow dwarf virus (BYDV), in England. We have used a genotyping-by-sequencing approach to study whether (a) there is any underlying population genetic structure at a national and regional scale in this pest that can disperse long distances; (b) the populations evolve as a response to environmental change and selective pressures; and (c) the populations comprise anholocyclic lineages. Individual R. padi were collected using the Rothamsted Insect Survey's suction-trap network at several sites across England between 2004 and 2016 as part of the RIS long-term nationwide surveillance. Results identified two genetic clusters in England that mostly corresponded to a North-South division, although gene flow is ongoing between the two subpopulations. These genetic clusters do not correspond to different life cycle types, and cyclical parthenogenesis is predominant in England.

17Genetic diversity is determinant for pest species' success and vector competence. Understanding the 18 ecological and evolutionary processes that determine the genetic diversity is fundamental to help 19 identify the spatial scale at which pest populations are best managed. In the present study, we 20 present the first comprehensive analysis of the genetic diversity and evolution of Rhopalosiphum 21 padi, a major pest of cereals and a main vector of the barley yellow dwarf virus (BYDV), in Great 22Britain. We have used a genotype by sequencing approach to study whether i) there is any 23 underlying population genetic structure in this long distant disperser pest at a national and regional 24 scale; ii) the populations evolve as a response to environmental change and selective pressures, and; 25 iii) the populations comprise anholocyclic lineages. Individual R. padi were collected using the 26Rothamsted Insect Survey's suction-trap network at several sites across England between 2004 and 27 2016 as part of the RIS long-term nationwide surveillance. Results identified two genetic clusters in 28Great Britain that mostly paralleled a North -South division, although gene flow is ongoing between 29 the two subpopulations. These different groups do not correspond to sexual and asexual types, 30 sexual reproduction being predominant in Great Britain, and could correspond to ecotypes. Results 31 also show that there is migration with gene flow across Great Britain, although there is a reduction 32 between the northern and southern sites with the Southwestern population being the most 33 genetically differentiated. There is no evidence for isolation-by-distance and other factors like 34 primary host distribution could influence the migration patterns. Finally, results also show no 35 evidence for the evolution of the R. padi population, and it is demographically stable despite the 36 ongoing environmental change. These results are discussed in view of their relevance to pest 37 management and the transmission of BYDV. 38