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.

Myzus persicae (Sulzer) collected in Scotland were characterized for four microsatellite loci, intergenic spacer fingerprints and the resistance mechanisms modified acetylcholinesterase (MACE), overproduced carboxylesterase and knockdown resistance (kdr). Microsatellite polymorphisms were used to define a limited number of clones that were either fully susceptible to insecticides or possessed characteristic combinations of resistance mechanisms. Within these clones, intergenic spacer fingerprints could either be very consistent or variable, with the latter indicating ongoing evolution within lineages, most likely derived from the same zygote. Two clones (termed A and B) possessed all three resistance mechanisms and predominated at sites treated with insecticides. Their appearance on seed potatoes and oilseed rape in Scotland in 2001 coincided with extensive insecticide use and severe control failures. Clones C, I and J, with no or fewer resistance mechanisms, were found in samples from 1995 and were dominant at untreated sites in 2001. A comparison of Scottish collections with those from other UK and non-UK sites provides insight into the likely origins, distribution and dynamics of M. persicae clones in a region where asexual (anholocyclic) reproduction predominates, but is vulnerable to migration by novel genotypes from areas of Europe where sexual (holocyclic) reproduction occurs.

Summary 0[ For a full assessment of explanations for the evolution of host!speci_city it is necessary to estimate the probability that a dispersing parasite _nds a host[ We develop a method of estimating this success rate from samples of dispersing parasites and populations resident on hosts[ 1[ Applying this method to data on the bird cherry!oat aphid\ Rhopalosiphum padi "L[#\ from southern Scotland in 0873Ð81\ we estimate that 9=5) of the autumn migrants _nd hosts[ 2[ With such a low success rate\ there should be selection for a broadening of host range\ to include any host on which the colonist|s _tness is more than about 9=5) of that on the normal hosts[ We argue that neither nutrition nor the need for {enemy! free space| are su.cient explanations of the host!speci_city of this animal\ and propose instead that it is the host|s role as a rendezvous for mating that constrains the migrants to their costly host!speci_city[ 3[ We also discuss the implications of this low success rate for the hypothesis that aphids speciate sympatrically through the formation of host races[ Key!words] host alternation\ migration\ overwintering\ Rhopalosiphum padi\ sympatric speciation[ Journal of Animal Ecology "0887# 56\ 652Ð662

1 The population of peach-potato aphid Myzus persicae in Scotland is comprised almost entirely of long-term asexual clones. 2 Over a ten year period, M. persicae from Scottish fields and suction traps were analysed with six microsatellite markers. 3 Out of 1497 individuals analysed, 14 clones (denoted A -N) comprised over 98% of the collection. 4 Some clones were particularly abundant but most clones had a widespread distribution on all available plants. 5 Clones E and L had distinct features in their distributions as clone L was geographically totally restricted to the north east of Scotland and clone E showed a marked preference for brassica crops. 6 Clones E and L provide direct evidence of a role for local adaptations in the distribution of M. persicae clones.

The potato cyst nematodes Globodera pallida and G. rostochiensis are listed in the EU Plant Health Directive 2000/29/EC and are also subject to the new EU Council Directive 2007/33/EC on the control of potato cyst nematodes, requiring unilateral suppression of these pests in Europe. At the same time there is also pressure to increase world trade in potatoes. Such pressure has to be balanced by the risks involved in the associated spread of these pests and subsequent problems in management. Populations of the potato cyst nematodes from outside Europe, in particular South America, which is considered the origin of G. pallida and G. rostochiensis, pose a risk to those European countries where limited genetic variability of these nematode species has been recorded. The development and usage of resistant cultivars under such conditions has formed a pivotal role in integrated management programmes in Europe. Molecular studies have shown that populations of G. pallida and G. rostochiensis from South America have a different genetic composition from those in Europe. The introduction of such populations would pose a threat to the use of resistant cultivars as a major tool in reducing the potential spread and damage caused by these species. At present, an inability to link precisely genetic variability to the virulence characteristics of a specific nematode population, and quickly identify the virulence status of intercepted populations for inspection purposes, strengthens the case for using plant health legislation to prevent their introduction.