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Habitat selection is a critical process that shapes the spatial distribution of species at local and regional scales. The mechanisms underlying habitat preference rely on environmental factors, species traits, and ecological interactions with other species. Here, we examined spatial segregation between two co-occurring aphid species (Rhopalosiphum maidis and R. padi) on wheat plants. We hypothesized that spatial segregation between these aphid species was mediated by aphid cuticular compounds left as chemical "footprints" on plant surfaces. Combining field and laboratory experiments, we first examined how plant microsites alter fitness by measuring the fecundity of each species. Next, we tested whether intra- and interspecific pre-inhabitation modified habitat selection in both aphid species. Both aphid species preferred and exhibited higher fecundity on wheat stems versus leaves. Laboratory trials showed that R. maidis pre-inhabitation altered R. padi spatial preference. By gas chromatography-mass spectrometry analysis and bioassays testing the effects of aphid density and footprint extracts, we found a density-dependent response, with R. padi avoiding locations previously inhabited by R. maidis. The chemical analysis of footprint crude extracts revealed a highly abundant compound, 1-hexacosanol, and when presented in the synthetic form, also elicited R. padi displacement. Altogether, it indicated that R. maidis footprints altered R. padi habitat selection with cuticular compounds playing a relevant role in the habitat selection process in co-occurring aphid species. [ABSTRACT FROM AUTHOR]

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Copyright of Journal of Agricultural Sciences, Belgrade is the property of University of Belgrade, Faculty of Agriculture and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In different parts of the world, aphid populations and their natural enemies are influenced by landscapes and climate. In the Neotropical region, few long-term studies have been conducted, maintaining a gap for comprehension of the effect of meteorological variables on aphid population patterns and their parasitoids in field conditions. This study describes the general patterns of oscillation in cereal winged aphids and their parasitoids, selecting meteorological variables and evaluating their effects on these insects. Aphids exhibit two annual peaks, one in summer–fall transition and the other in winter-spring transition. For parasitoids, the highest annual peak takes place during winter and a second peak occurs in winter–spring transition. Temperature was the principal meteorological regulator of population fluctuation in winged aphids and parasitoids during the year. The favorable temperature range is not the same for aphids and parasitoids. For aphids, temperature increase resulted in population growth, with maximum positive effect at 25°C. Temperature also positively influenced parasitoid populations, but the growth was asymptotic around 20°C. Although rainfall showed no regulatory function on aphid seasonality, it influenced the final number of insects over the year. The response of aphids and parasitoids to temperature has implications for trophic compatibility and regulation of their populations. Such functions should be taken into account in predictive models. [ABSTRACT FROM AUTHOR]

Long-term studies (2012-2018) of the formation of the Rhopalosiphum padi (L.) heteroecious population (number of remigrants, oviparae and eggs in autumn, number of perished eggs, fundatrices larvae, timing of flight of emigrants in spring) on the two samples of primary host Padus avium Mill. and P. avium x P. virginiana (L.) characterized by various morpho-physiological features have been carried out. By the methods of mathematical statistics, it has been proved that this formation occurs under the significant influence of the year conditions (A), host plant characteristics (B) and these factors interaction (AB). The most visible was their highly significant impact on the number of wintering aphid eggs (A = 200.42; B = 142.6; AB = 25.612). Plant characteristics such as significantly larger leaf area from the middle part of the shoot on P. avium x P. virginiana, than on P. avium (t = 8.37; p0.01 = 2.85) was important for attracting remigrants and the prone buds on P. avium x P. virginiana - for oviposition and survival of eggs. Correlation between the period of leaf fall and number of aphid eggs on both bird-cherry samples is presented. The effect of weather conditions on R. padi and primary hosts relationships is discussed. Correlation (r = 0.76; p = 0.0048) between average temperature of October and eggs number on P. avium is given. R. fundatrices. [ABSTRACT FROM AUTHOR]

Infection with barley yellow dwarf virus (BYDV), caused by strains of virus belonging to the family Luteovirideae including BYDV‐PAV, can result in significant yield losses in autumn sown cereals following transmission by aphid vectors such as Rhopalosiphum padi (Homoptera: Aphididae) and Sitobion avenae (Homoptera: Aphididae). Spatial and temporal variance in the infectivity of alate populations influences risk to crops from the disease, which is greatest on infection at early crop growth stages. A decision support system (DSS) to guide optimised integration of crop protection strategies through risk assessment would help avoid unnecessary application of synthetic insecticides. This study contributes to the development of a DSS by exploring the viability and relevance of a methodology to detect virus levels in individual aphids trapped in‐crop using yellow sticky traps. Using a reverse transcription polymerase chain reaction assay, the detectability of virus from a BYDV‐PAV‐positive control colony was found not to be reduced by the process of trapping, extraction and cold storage, but did drop significantly after between 3 and 7 days of exposure on trap. This method has potential to contribute to localised risk assessment and guide optimisation of crop protection strategies. [ABSTRACT FROM AUTHOR]

We present a synthetic review and expert consultation that assesses the actual risks posed by arthropod pests in four major crops, identifies targets for integrated pest management (IPM) in terms of cultivated land needing pest control and gauges the implementation "readiness" of non-chemical alternatives. Our assessment focuses on the world's primary target pests for neonicotinoid-based management: western corn rootworm (WCR, Diabrotica virgifera virgifera) in maize; wireworms (Agriotes spp.) in maize and winter wheat; bird cherry-oat aphid (Rhopalosiphum padi) in winter wheat; brown planthopper (BPH, Nilaparvata lugens) in rice; cotton aphid (Aphis gossypii) and silver-leaf whitefly (SLW, Bemisia tabaci) in cotton. First, we queried scientific literature databases and consulted experts from different countries in Europe, North America, and Asia about available IPM tools for each crop-pest system. Next, using an online survey, we quantitatively assessed the economic relevance of target pests by compiling country-level records of crop damage, yield impacts, extent of insecticide usage, and "readiness" status of various pest management alternatives (i.e., research, plot-scale validation, grower-uptake). Biological control received considerable scientific attention, while agronomic strategies (e.g., crop rotation), insurance schemes, decision support systems (DSS), and innovative pesticide application modes were listed as key alternatives. Our study identifies opportunities to advance applied research, IPM technology validation, and grower education to halt or drastically reduce our over-reliance on systemic insecticides globally. [ABSTRACT FROM AUTHOR]

Aphids are renowned plant parasites of agriculture, horticulture and forestry, causing direct physical damage by sucking phloem and especially by transmission of plant pathogenic viruses. The huge yield loss they cause amounts to hundreds of millions of dollars globally, and because of this damage and the intense efforts expended on control, some 20 species are now resistant to pesticides worldwide. Aphids represent an ancient, mainly northern temperate group, although some species occur in the tropics, often as obligate asexual lineages or even asexual 'species'. However, besides their notoriety as enemies of plant growers, aphids are also extremely interesting scientifically, especially at the molecular and genetic levels. They reproduce mainly asexually, one female producing 10–90 offspring in 7–10 days and therefore, theoretically, could produce billions of offspring in one growing season in the absence of mortality factors (i.e. climate/weather and antagonists). In this overview, we provide examples of what molecular and genetic studies of aphids have revealed concerning a range of topics, especially fine-grained ecological processes. Aphids, despite their apparently limited behavioural repertoire, are in fact masters (or, perhaps more accurately, mistresses) of adaptation and evolutionary flexibility and continue to flourish in a variety of ecosystems, including the agro-ecosystem, regardless of our best efforts to combat them. [ABSTRACT FROM AUTHOR]

DNA barcoding is highly effective for identifying specimens once a reference sequence library is available for the species assemblage targeted for analysis. Despite the great need for an improved capacity to identify the insect pests of crops, the use of DNA barcoding is constrained by the lack of a well-parameterized reference library. The current study begins to address this limitation by developing a DNA barcode reference library for the pest aphids of Pakistan. It also examines the affinities of these species with conspecific populations from other geographic regions based on both conventional taxonomy and Barcode Index Numbers (BINs). A total of 809 aphids were collected from a range of plant species at sites across Pakistan. Morphological study and DNA barcoding allowed 774 specimens to be identified to one of 42 species while the others were placed to a genus or subfamily. Sequences obtained from these specimens were assigned to 52 BINs whose monophyly were supported by neighbor-joining (NJ) clustering and Bayesian inference. The 42 species were assigned to 41 BINs with 38 showing BIN concordance. These species were represented on BOLD by 7,870 records from 69 countries. Combining these records with those from Pakistan produced 60 BINs with 12 species showing a BIN split and three a BIN merger. Geo-distance correlations showed that intraspecific divergence values for 49% of the species were not affected by the distance between populations. Forty four of the 52 BINs from Pakistan had counterparts in 73 countries across six continents, documenting the broad distributions of pest aphids. [ABSTRACT FROM AUTHOR]

Insect populations are prone to respond to global changes through shifts in phenology, distribution and abundance. However, global changes cover several factors such as climate and land‐use, the relative importance of these being largely unknown. Here, we aim at disentangling the effects of climate, land‐use, and geographical drivers on aphid abundance and phenology in France, at a regional scale and over the last 40 years. We used aerial data obtained from suction traps between 1978 and 2015 on five aphid species varying in their degree of specialization to legumes, along with climate, legume crop area and geographical data. Effects of environmental and geographical variables on aphid annual abundance and spring migration dates were analyzed using generalized linear mixed models. We found that within the last four decades, aphids have advanced their spring migration by a month, mostly due to the increase in temperature early in the year, and their abundance decreased by half on average, presumably in response to a combination of factors. The influence of legume crop area decreased with the degree of specialization of the aphid species to such crops. The effect of geographical variation was high even when controlling for environmental variables, suggesting that many other spatially structured processes act on aphid population characteristics. Multifactorial analyses helped to partition the effects of different global change drivers. Climate and land‐use changes have strong effects on aphid populations, with important implications for future agriculture. Additionally, trait‐based response variation could have major consequences at the community scale. [ABSTRACT FROM AUTHOR]

Interactions occurring between the insect and its host plant are an important aspect of understanding the process of species dispersal and the colonisation of new host plants. Aphid adaptive processes in response to the changing vegetation cover include morphological, developmental, behavioural, and metabolic adaptations. The activity of enzymes is presumed to be involved in protecting the insects from the toxic effects of oxidative stress and is an enzymatic defense mechanism for insects. The activity of antioxidant (superoxide dismutase and catalase), detoxifying (glutathione S-transferase and β-glucosidase), and oxidoreductive (peroxidase and polyphenol oxidase) enzymes in the tissues of Cinara (Cupressobium) tujafilina (Del Guercio) aphids during host switch were studied. The performed studies have demonstrated that the environmental stress represented by the host switch induces the aphid organisms to produce an instant response manifested as increased SOD and CAT activity in only 24 hr after the colonisation of a new host plant. Host plant changeover caused a significant increase in the average β-glucosidase activity in C. tujafilina tissues as early as after 24 hr. Also, the increased GST activity level persisted in aphid tissues throughout the entire experiment, which was 96 hr. The results of our study have demonstrated that switching a host plant by aphids activates both oxidoreductases (PPO, POD) in the tissues of C. tujafilina. They have also confirmed that these enzymes act in a complementary fashion in the aphid body. Due to the flexible activity of enzymes, C. tujafilina is able to rapidly respond and adjust to various hosts, thus achieving adaptive success. [ABSTRACT FROM AUTHOR]

Global warming has the potential to affect many animal species, in particular temperature-dependent insects with their short generation times and high reproductive rates which facilitate adaptations to long-term climatic fluctuations. Aphids are the model species in studying the association of insect biology with large-scale climate fluctuations because they multiply only within a certain range of temperatures and their rate of development directly depends on temperature. Here, we investigate the effect of climate warming on phenology and voltinism of the juniper aphid (Cinara juniperiDe Geer 1773), a native species of a temperate climate zone in Poland. We also experimentally test for the temperature optimum of the study species. Our study demonstrated that environmental conditions significantly affected phenology of juniper aphid. The timing of larval emergence depended on mean temperatures in March, and in warmer years larvae appeared earlier. The emergence of the sexual generation was related to mean temperatures in August, and higher temperatures resulted in later sexual reproduction. Despite the elongation of the entire life cycle, by almost 3 months, we observed only one additional generation in warmer years. A possible explanation for this pattern may be that the increase in temperature recorded in recent years went beyond the temperature optimum of the study species. Our chamber experiment supports this assumption – juniper aphids developed faster and reproduced more effectively at 20 °C than at 25 °C. [ABSTRACT FROM PUBLISHER]

Under climate change, alterations to precipitation and temperature regimes are expected to impact ecosystem structure and function. These impacts may in part be determined by feedbacks between plants and associated microbes, including both endophytic fungal symbionts and viral pathogens., To test potential key components of these feedbacks in a grassland system, we conducted a field experiment that factorially manipulated temperature regime, precipitation regime and endophyte infection of a dominant species, Schedonorus arundinaceus. After one growing season, we evaluated the four most frequently occurring grass species for infection by three species of barley and cereal yellow dwarf viruses (B/ CYDVs). For S. arundinaceus, we also tracked changes in viral prevalence over an additional two growing seasons, for a total of three growing seasons., Plant species identity played a strong role in determining virus prevalence; Poa pratensis and Paspalum dilatatum were more frequently infected than either S. arundinaceus (endophyte infected or endophyte free) or Eleusine indica. Both elevated temperature and elevated precipitation impacted virus prevalence, but effects varied among years and interacted with fungal endophyte symbiosis for S. arundinaceus., In the final year of data collection, elevated precipitation increased virus prevalence in endophyte-infected, but not endophyte-free, S. arundinaceus. In the same year, but regardless of endophyte infection, elevated temperature by itself increased virus prevalence for S. arundinaceus. This effect of temperature on virus prevalence may have been driven by vector abundance because the viruses are obligately aphid-transmitted, and aphids were found more frequently in heated plots., Synthesis. Overall, our investigation experimentally demonstrates strong combined impacts of biotic and abiotic factors on disease dynamics in a grassland system. Impacts of climate change on virus prevalence in grasslands may depend on the responses of aphid vectors and the presence of endophytic fungal symbionts. [ABSTRACT FROM AUTHOR]

Between 1975 to 2011, aphid Relative Growth Rates (RGR) were modelled as a function of mean outdoor temperature and host plant phenology. The model was applied to the grain aphid Sitobion avenae using data on aphid counts in winter wheat at two different climate regions in France (oceanic climate, Rennes (western France); continental climate, Paris). Mean observed aphid RGR was higher in Paris compared to the Rennes region. RGR increased with mean temperature, which is explained by aphid reproduction, growth and development being dependent on ambient temperature. From the stem extension to the heading stage in wheat, there was either a plateau in RGR values (Rennes) or an increase with a maximum at heading (Paris) due to high intrinsic rates of increase in aphids and also to aphid immigration. From the wheat flowering to the ripening stage, RGR decreased in both regions due to the low intrinsic rate of increase in aphids and high emigration rate linked to reduced nutrient quality in maturing wheat. The model validation process showed that the fitted models have more predictive power in the Paris region than in the Rennes region. [ABSTRACT FROM AUTHOR]

The article presents a study to find whether snow depth be used to predict the distribution of the high Arctic aphid Acyrthosiphon svalbardicum on Spitsbergen Island, Norway. The study compared multiple transects over a series of ridges and did observe at a larger scale the predictions. Eggs were found in those patches that showed shallower snow depths in winter, though the aphid was more widely distributed across areas that showed a range of snow depths.

Ile Amsterdam (37850'S, 77830'E, 55 km2) and Ile Saint-Paul (38843'S, 77831'E, 7km2) are very isolated volcanic islands which were originally colonized by a few invertebrate fauna and flora. Invasivespecies richness has then increased along with human activity. A three-year monitoring programme (1997, 2000, 2001) and a summer campaign (2007) allowed species diversity, host plants, abundance and phenology of introduced aphids and natural enemies to be described. Seven cosmopolitan aphid species have been found on Ile Amsterdam (Aulacorthum solani, A. circumflexum, Macrosiphum euphorbiae, Myzus ascalonicus, M. cymbalariae, M. ornatus and Rhopalosiphum padi) and three on Ile Saint-Paul (A. solani, M. cymbalariae and R. padi). On Ile Amsterdam, these aphids were found on 28 host plants (out of 57 sampled plants), mainly introduced species. Phylica arborea was the only native plant much colonized by one aphid species, A. circumflexum. Aphids were mainly present on the base or in this vicinity. One Hymenopteran parasitoid, Aphidius matricariae, and two hyperparasites (Dendrocerus aphidum and Phaenoglyphis villosa), probably introduced along with their host, were collected. Aphid activity is very low during the autumn (March-May) and at a maximum in spring and summer. Their density and diversity decrease with distance from the research station. From these results, the possible impact of aphids on native plants is discussed. [ABSTRACT FROM AUTHOR]

At large spatial scales, high numbers of people tend to be located in regions rich in biodiversity. This pattern has been reported for plants, some invertebrate groups, amphibians, reptiles, birds and mammals, but little is known about whether aphids conform to it. Aphids originated from temperate regions of the boreal hemisphere and are thus exceptionally species-poor in the tropics. Here, we test whether aphid species richness is related to human population variation in European countries. The number of aphid species increases significantly with increasing human population size. This happens also when controlling for country area, latitude and plant species richness, which are not factors significantly affecting the response variable in the multivariate model. Given that the species–area and species–people relationships have a slope shallower than 1, small countries have a higher aphid species density relative to area and to people than large ones. There is no evidence that the species-people correlation for aphids in European countries arises because both variables are related to increasing temperature or precipitation. Potential mechanisms underlying the findings could thus be a sampling artefact or an influence of habitat heterogeneity. There is a need for an increase in research, public awareness and conservation of large-scale aphid biodiversity. [ABSTRACT FROM AUTHOR]

Many agricultural pest species occur in seasonal metapopulations with a period of asexual reproduction. We use evolutionary theory to predict timing of dispersal for such species, and identify four sequential phases: no dispersal, dispersal from initially occupied patches, dispersal from later colonized patches, and no dispersal. The third type of phase occurs only when reproductive rates are relatively high; we speculate that this could explain why among aphids there can be either one or two waves of dispersal during a season, depending on the species. Our model also explains other features of aphid biology, including a summer crash in colony size, and a decline in the number of colonies towards the end of each reproductive season. The presence of an additional surge of dispersal becomes more likely as season length increases, and does not require further evolution. This could have profound implications for pest management during future climatic warming. [ABSTRACT FROM AUTHOR]

The migration of cereal aphids and the time of their arrival on winter cereal crops in autumn and spring are of particular importance for plant disease (e.g. barley yellow dwarf virus infection) and related yield losses. In order to identify days with migration potentials in autumn and spring, suction trap data from 29 and 45 case studies (locations and years), respectively, were set-off against meteorological parameters, focusing on the early immigration periods in autumn (22 September to 1 November) and spring (1 May to 9 June). The number of cereal aphids caught in a suction trap increased with increasing temperature, global radiation and duration of sunshine and decreased with increasing precipitation, relative humidity and wind speed. According to linear regression analyses, the temperature, global radiation and wind speed were most frequently and significantly associated with migration, suggesting that they have a major impact on flight activity. For subsequent model development, suction trap catches from different case studies were pooled and binarily classified as days with or without migration as defined by a certain number of migrating cereal aphids. Linear discriminant analyses of several predictor variables (assessed during light hours of a given day) were then performed based on the binary response variables. Three models were used to predict days with suction trap catches ≥1, ≥4 or ≥10 migrating cereal aphids in autumn. Due to the predominance of Rhopalosiphum padi individuals (99.3% of total cereal aphid catch), no distinction between species ( R. padi and Sitobion avenae) was made in autumn. As the suction trap catches were lower and species dominance changed in spring, three further models were developed for analysis of all cereal aphid species, R. padi only, and Metopolophium dirhodum and S. avenae combined in spring. The empirical, cross-classification and receiver operating characteristic analyses performed for model validation showed different levels of prediction accuracy. Additional datasets selected at random before model construction and parameterization showed that predictions by the six migration models were 33–81% correct. The models are useful for determining when to start field evaluations. Furthermore, they provide information on the size of the migrating aphid population and, thus, on the importance of immigration for early aphid population development in cereal crops in a given season. [ABSTRACT FROM AUTHOR]

Many organisms considered as strictly clonal may in fact experience some rare events of sexual reproduction with their sexual relatives. However, the rate of sexual–asexual gene flow has rarely been assessed mainly because its evaluation is difficult to achieve in the field. In the cyclically parthenogenetic aphid Rhopalosiphum padi, two main sets of lineages, differing in their investment in sexual reproduction and in their genetic attributes, co-exist even at a very fine scale: the ‘sexual’ lineages which have a full commitment to the sexual reproduction, and the ‘facultatively asexual’ lineages, which allocate investment in the sexual and parthenogenetic reproduction. This system offers a unique opportunity to tackle the genetic interactions between two contrasting reproductive modes. Here, we provide evidence that gene flow occurred between sexual and facultatively asexual lineages of R. padi. We carefully examined the shuffling in phenotypic and genotypic variation following a sexual reproduction event that took place in the field. Combining genotypic data and phenotypic measurements showed that this gene mixing led to the production of a wide array of reproductive modes, including strictly asexual lineages. Finally, we discuss the central role played by facultatively asexual lineages on the maintenance of reproductive mode variation. [ABSTRACT FROM AUTHOR]

Field catches of Phorodon humuli during 2 years (2000 and 2001) by means of Moericke and suction trap were compared in the province of León (north-west Spain). Positive correlations between the catches with Moericke traps and the catches with the suction trap were found. Positive correlations between the catches with the suction trap and the appearances of the first colonies on crops were also found. These results show that suction trap catches are useful for monitoring the start of spring flight of P. humuli and could serve as a guideline for application of treatments for control of this aphid. [ABSTRACT FROM AUTHOR]

Sexual morph production inPhorodon humuliis controlled by daylength. Wingless aphids reared from birth in short-day conditions (LD 12 : 12 h) and transferred when adult to long-day conditions (LD 18 : 6 h) produce only gynoparae and males until death some 7 weeks later, whereas those reared in long days and transferred to short days produce 20% wingless parthenogenetic females, 50% gynoparae and 30% of males in an overlapping sequence. No winged morph capable of re-infesting hop is produced. Less mature embryos are more sensitive to short days than older embryos because 100% of the former became gynoparae after 4 days of exposure of their mothers, and 59% when their mothers were exposed for the 4 days immediately preceding the birth of their offspring. Two days of exposure to short days switches 94% of young embryos from wingless to gynopara production when mature. The response to short days is irreversible. Wingless aphids reared from birth to adult in short days produce 30% fewer offspring than those reared to the same stage in long days and are male-biased, with 76–78% of their offspring being male. [ABSTRACT FROM AUTHOR]

The purpose of this study was to improve understanding of the relationship between the spatial patterns of an important insect pest, the aphidMyzus persicae, and aspects of its environment. The main objectives were to determine the predominant geographical, climatic and land use factors that are linked with the aphid's distribution, to quantify their role in determining that distribution, including their interacting effects and to explore the ability of artificial neural networks (ANNs) to provide predictive models.The study focused on four spatial scales to account for the aphid data base characteristics and available land use data sets: Europe; a broad zone over Europe covering Belgium, Denmark, France, Ireland, Italy, The Netherlands, Scotland, Sweden and Wales (Regio data base coverage); North-West Europe (i.e. Belgium, France and the United Kingdom); and England with Wales.Multiple linear regression (MLR) was used to identify the variables in the Geographic location, Climate and Land use groups, that explained significant proportions of the variance inM. persicaetotal annual numbers and Julian date of first capture. A variance partitioning procedure was used to measure the fraction of the variation that can be explained by each environmental factor and of shared variation between the different factors. Finally, ANNs were employed as an alternative modelling approach for the two largest study areas, i.e. Europe and the Regio data base coverage, to determine whether the relationship between aphid and environmental variables was better described by more complex functions as well as their ability to generalize to new data.Land use variables are shown to play a significant role in explaining aphid numbers. The area of agricultural crops, in particular oilseed rape, is positively correlated withM. persicaeannual numbers. Among the climatic variables, rainfall is negatively correlated with aphid numbers and temperature is positively correlated. The geographical components also explain a significant part of aphid annual numbers. However, the variance partitioning procedure indicates that while each group has an effect, none is dominant. Aphid first capture is mainly explained by climate where rainfall tends to delay migration and warmer conditions tend to advance it. Climate accounts for the greatest part of the variance when considered separately from the other factors. The geographical and land use components also have a significant effect on first capture at each scale, but their direct contribution is negligible. The ability of the ANN models to generalize to new total numbers and phenological data compared with MLR models was less for Europe (9 and 6% increase in the variance accounted for, respectively) than for the Regio data coverage where an increase of 44% in the variance accounted for was observed.This research supports the hypothesis that climate, land use and geographical location play a role in determining patterns of aphid annual numbers and phenology. The ability of ANN models to predict aphid distribution is improved by the inclusion of temporal land use data. However, identification of the processes involved in such relationships is difficult due to numerous interactions between the environmental factors. [ABSTRACT FROM AUTHOR]

Cyclically parthenogenetic organisms may have facultative asexual counterparts. Such organisms, including aphids, are therefore interesting models for the study of ecological and genetic interactions between lineages differing in reproductive mode. Earlier studies on aphids have revealed major differences in the genetic outcomes of populations that are possibly resulting mostly either from sexual or from asexual reproduction. Besides, notable gene flow between sexual and asexual derivatives has been suspected, which could lead to the emergence of new asexual lineages. The present study examines the interplay between these lineages and is based on analyses of population structure of individuals that may contribute to the pool of sexual reproductive forms in the host alternating aphidRhopalosiphum padi. Using a Bayesian assignment method, we first show that the sexual forms ofR. padion mating sites encompass two genetically distinct clusters of individuals in the western part of France. The first cluster included unique genotypes of sexual lineages, while the second cluster included facultatively asexual lineages in numerous copies, the reproductive mode of the two clusters being confirmed by reference clones. Sexual reproductive forms produced by sexual and facultatively asexual lineages are thus admixed at mating sites which gives a large opportunity for the two clusters to mate with each other. Nevertheless, this study also highlights, as previously demonstrated, that the two clusters retained high genetic differentiation. Possible explanations for the inferred limited genetic exchanges are advanced in the discussion, but further dedicated investigations are required to solve this paradox. [ABSTRACT FROM AUTHOR]

Summarizes the results of two surveys of the temporal and spatial dynamics of insecticide resistance in the aphid Myzus persicae in England. Methodology; Results; Discussion.

Arctic ecosystems are subjected to strong environmental constraints that prevent both the colonization and development of many organisms. In Svalbard, few aphid species have established permanent populations. These high arctic aphid species have developed peculiar life-history traits such as shortened life cycles and reduced dispersal capacities. Here, we present data on the distribution and population genetics of Acyrthosiphon svalbardicum in Spitsbergen, the main island of the Svalbard archipelago, and compared its genetic structure with that of its close relative Acyrthosiphon brevicorne, sampled in the top of Scandinavian mainland. We found that A. svalbardicum is common but heterogeneously distributed along the west coast of Spitsbergen. We recorded this species up to 79°12', which constitutes the northernmost location for any aphid. Genetic structure examined using microsatellite markers showed more pronounced spatial differentiation in A. svalbardicum than in A. brevicorne populations, presumably due to reduced dispersal capacities in the former species. Although populations of A. brevicorne and A. svalbardicum were well-delineated at nuclear loci, they shared similar cytoplasmic DNA haplotypes as revealed by sequence analysis of two DNA barcodes. These results raise questions about whether these two taxa are different species, and the colonization sources and history of the Svalbard archipelago by A. svalbardicum. [ABSTRACT FROM AUTHOR]