Comparación de la estructura de las poblaciones de áfidos (Hom. Aphididae) alados capturados en León por diferentes tipos de trampas

De 1980 a 1983 y de 1986 a 1988 se mantuvieron instaladas en la Escuela de Ingeniería Técnica Agricola de la Universidad de León trampas de succión y de Moericke a distintas alturas para conocer la composición aérea de áfidos alados en la zona estudiada. Mediante analisis factoriales de correspondencias se comparan los resultados de las capturas obtenidas en los distintos tipos de trampas.From 1980 to 1983 and from 1986 to 1988 a suction trap and Moericke traps at different heights have been installed at the Escuela de Ingeniería Técnica Agrícola of the University of León, to know the aerial composition of aphids. Some statistics analysis are made to compare the results of the different traps

Comparación de la estructura de las poblaciones de áfidos (Hom. Aphididae) alados capturados en León por diferentes tipos de trampas

De 1980 a 1983 y de 1986 a 1988 se mantuvieron instaladas en la Escuela de Ingeniería Técnica Agricola de la Universidad de León trampas de succión y de Moericke a distintas alturas para conocer la composición aérea de áfidos alados en la zona estudiada. Mediante analisis factoriales de correspondencias se comparan los resultados de las capturas obtenidas en los distintos tipos de trampas.From 1980 to 1983 and from 1986 to 1988 a suction trap and Moericke traps at different heights have been installed at the Escuela de Ingeniería Técnica Agrícola of the University of León, to know the aerial composition of aphids. Some statistics analysis are made to compare the results of the different traps

Étude de l'influence de la hauteur de piégeage sur les captures de pucerons ailés en différents sites et sur plusieurs années

La variabilité de l'influence de la hauteur de piégeage sur les captures de pucerons ailés par pièges jaunes a été étudiée en comparant les résultats obtenus dans 7 sites géographiquement distants et durant 5 années consécutives. Tous les pièges ont été disposés dans le même environnement cultural afin de minimiser les sources exogènes de variabilité. L'analyse a porté sur près de 40 000 pucerons et 121 taxons et a permis de classer les 23 espèces les mieux capturées en 4 groupes : 6 espèces dont les captures sont régulièrement influencées par la hauteur de piégeage. Quel que soit le site ou l'année, 5 espèces dont les captures subissent moins régulièrement l'effet de la hauteur de piégeage, 6 espèces pour lesquelles l'effet dû à la hauteur de piégeage est faible ou instable, et enfin 6 espèces dont les captures semblent indépendantes de la hauteur de piégeage. Parmi les espèces montrant une différence significative de capturabilité, 8 sont piégées en plus grand nombre à 0,7 m et 3 à 0,0 m. Ces résultats montrent cependant que le principal facteur d'hétérogénéité réside dans les fluctuations interannuelles qui permettent d'expliquer environ 50% de la variabilité observée dans les captures.Study of the effect of the height of trapping on catches of alate aphids at different sites and over several years. The variability in the influence of the height of trapping on the abundance of catches of alate aphids was studied via comparisons between 2 heights of trapping at 7 different sites operating over 5 yr in succession. All the traps were set in the same cultural environment in order to limit the influence of other possible factors of variability. The study was based on catches of nearly 40 000 individuals and 121 taxa. It allowed classification of the 23 more abundant species into 4 groups: 6 species whose catches were regularly dependent on the height of trapping, 5 species whose catches were also related to the height of trapping but less regularly, 6 species for which the height effect was weak or irregular and 6 species showing no effect. Among the 11 first species, 8 were sampled at 0.7 m in a higher number than at 0.0 m and 3 were better sampled at 0.0 m. The main factor of heterogeneity remained annual variations which constituted 50% of the total variability observed in the data set

Distribution patterns of invertebrate species introduced into the sub-Antarctic Kerguelen Islands

International audienc

Temporal habitat variability and the maintenance of sex in host populations of the pea aphid

The evolutionary maintenance of sex, despite competition from asexual reproduction, has long intrigued the evolutionary biologists owing to its numerous apparent short-term costs. In aphids, winter climate is expected to determine the maintenance of sexual lineages in the high latitude zones owing to their exclusive ability to produce frost-resistant eggs. However, diverse reproductive modes may coexist at a local scale where climatic influence is counteracted by microgeographical factors. In this study, we tested the influence of local habitat characteristics on regional coexistence of reproductive modes in the pea aphid, Acyrthosiphon pisum. In the laboratory, the induction of sexual morph production of many pea aphid genotypes from the local fields of annual (pea and faba bean) and perennial (alfalfa and red clover) crops in Western France indicated that A. pisum lineages from annual crops had a significantly higher investment in sexual reproduction than A. pisum lineages from the perennial hosts. We propose that temporal habitat variability exerts a selective pressure to maintain the sexual reproduction in A. pisum. The ecological and evolutionary consequences of the association between the mode of reproduction and the host population on gene flow restriction and on ecological specialization are discussed

Characteristics of introduced Aphididae species, an endemic fly (Anatalanta aptera) and an introduced ground beetle (Merizodus soledadinus) on the Kerguelen Islands

The suite of environments and anthropogenic modifications of sub-Antarctic islands provide key opportunities to improve our understanding of the potential consequences of climate change and biological species invasions on terrestrial ecosystems. The profound impact of human introduced invasive species on indigenous biota, and the facilitation of establishment as a result of changing thermal conditions, has been well documented on the French sub-Antarctic Kerguelen Islands (South Indian Ocean). The present study provides an overview of the vulnerability of sub-Antarctic terrestrial communities with respect to two interacting factors, namely climate change and alien insects. We present datasets assimilated by our teams on the Kerguelen Islands since 1974, coupled with a review of the literature, to evaluate the mechanism and impact of biological invasions in this region. First, we consider recent climatic trends of the Antarctic region, and its potential influence on the establishment, distribution and abundance of alien insects, using as examples one fly and one beetle species. Second, we consider to what extent limited gene pools may restrict alien species' colonisations. Finally, we consider the vulnerability of native communities to aliens using the examples of one beetle, one fly, and five aphid species taking into consideration their additional impact as plant virus vectors. We conclude that the evidence assimilated from the sub-Antarctic islands can be applied to more complex temperate continental systems as well as further developing international guidelines to minimise the impact of alien species

Do non-native plants affect terrestrial arthropods in the sub-Antarctic Kerguelen Islands?

Biological invasions are a major threat to the terrestrial ecosystems of the sub-Antarctic islands. While non-native plants generally have negative impacts on native arthropods, few studies have investigated how both native and non-native arthropods and plants interact in the sub-Antarctic islands. This was the aim of our study, which was conducted on three islands of the Kerguelen archipelago. The design was based on the spatial proximity of areas dominated by non-native or native plant species. Trait-based indices were calculated to characterize the functional structure of plant communities, considering plant stature and leaf traits. Native and non-native vegetation had contrasting functional composition but their functional diversity was similar. The effects of the type of vegetation, native or non-native, and plant functional diversity on arthropods were tested. Native macro-arthropod richness and abundance were similar or higher in non-native vegetation, and benefited from greater plant functional diversity. Abundances of macro-herbivores, macro-decomposers and macro-predators were also similar or higher in non-native vegetation. Conversely, the abundances of micro-arthropods, Symphypleona springtails and Oribatida mites, were higher in native vegetation but we also found that plant functional diversity had a negative effect on Symphypleona. Our results suggest that non-native plants can affect micro-arthropods directly or indirectly, likely through their effects on abiotic factors. By affecting macro-arthropod abundances across different trophic groups and by depleting micro-arthropods, non-native plants can alter trophic interactions, functional balances and the functioning of whole ecosystem