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Aebi, Alexandre

Nom
Aebi, Alexandre
Affiliation principale
Site web
Fonction
MER
Email
alexandre.aebi@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/769
_
0000-0003-2309-1497

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  • Publication
    Métadonnées seulement
    The potential of native parasitoids for the control of Mexican bean beetles: A genetic and ecological approach
    (2008)
    Aebi, Alexandre 
    ;
    Shani, Tal
    ;
    Hansson, Christer
    ;
    Contreras-Garduno, Jorge
    ;
    Mansion, Guilhem
    ;
    Benrey, Betty 
  • Publication
    Accès libre
    Ecological distribution and niche segregation of sibling species: the case of bean beetles, Acanthoscelides obtectus Say and A. obvelatus Bridwell
    (2006)
    Alvarez, Nadir
    ;
    Mercier, Lény
    ;
    Hossaert-McKey, Martine
    ;
    Contreras-Garduño, Jorge
    ;
    Kunstler Georges
    ;
    Aebi, Alexandre 
    ;
    Benrey, Betty 
    1. Molecular techniques have greatly added to the number of known sympatric cryptic species in insects. Ecological differences between these newly distinguished species are little explored, but niches often appear to overlap strongly. These cases are good models for exploring new ideas about species coexistence and community structure.
    2. Acanthoscelides obtectus and A. obvelatus are two sister species of bean bruchids, which have been confused until the last decade. One important ecological difference between them has emerged, however: A. obtectus is multivoltine and now distributed worldwide, whereas A. obvelatus is univoltine and restricted to Mesoamerica. Where their ranges overlap, the two species share the same host plants and larvae can sometimes complete development in the same seed.
    3. The analysis of 27 622 Mexican individuals of the two species in 2001-2002 and 2002-2003 indicates that their niches overlap, but are differentiated with respect to altitude and the kind of beans (wild vs. domesticated). The principal patterns in their relative abundance in different habitats, and at different seasons, were constant from one year to the next.
    4. As sympatry of these species seems to be of recent origin, the observed niche differentiation may not have evolved in response to competition, but could instead be the consequence of physiological differences, evolved independently in each species in allopatry, that pre-adapted them for different altitudes and kinds of resources.
    5. The combination of biological and historical factors thus appears to allow these two sibling species to coexist in sympatry, despite their broadly overlapping ecological niches.
  • Publication
    Accès libre
    Sibling species of bean bruchids: a morphological and phylogenetic study of Acanthoscelides obtectus Say and Acanthoscelides obvelatus Bridwell
    (2005)
    Alvarez, Nadir
    ;
    Hossaert-McKey, Martine
    ;
    Rasplus, J.-Y.
    ;
    McKey, Doyle
    ;
    Mercier, Lény
    ;
    Soldati, L.
    ;
    Aebi, Alexandre 
    ;
    Shani, T.
    ;
    Benrey, Betty 
    Acanthoscelides Schilsky is a large genus of neotropical bruchid beetles, in which most species show host plant specialization. Acanthoscelides obtectus and Acanthoscelides obvelatus are two sibling species specialized on Phaseolus beans, and are therefore considered pests. Up to now, the status of these two taxa has remained unclear, the few studies conducted having failed to elucidate whether these are two differentiated species or a single morphologically variable species. In addition, A. obvelatus has not been taken into account in the great majority of studies of bean bruchids. In this morphological and genetic study, we show that A. obtectus and A. obvelatus are two 'true' non-hybridizing species, which diverged about 22 Mya. Although the two species demonstrate only few morphological differences, we point out some diagnostic characters that enable their identification in the field. We also address a genetic method of differentiation of the two species, based on species-specific microsatellite loci. The strong morphological resemblance of these two species, despite their ancient divergence, may be the result of evolutionary stasis, which could be the consequence of stabilizing selection. Niche differentiation could enable the two species to coexist indefinitely.
  • Publication
    Métadonnées seulement
    Microsatellite markers in a complex of Horismenus sp.(Hymenoptera: Eulophidae), parasitoids of bruchid beetles
    (2004)
    Aebi, Alexandre 
    ;
    Alvarez, Nadir
    ;
    Butcher, R. D. J.
    ;
    Hansson, Christer
    ;
    Risterucci, A. M.
    ;
    Benrey, Betty 
  • Publication
    Métadonnées seulement
  • Publication
    Accès libre
    Isolation and characterization of polymorphic microsatellite loci in Acanthoscelides obvelatus Bridwell (Coleoptera: Bruchidae)
    (2003)
    Alvarez, Nadir
    ;
    Aebi, Alexandre 
    ;
    Risterucci, A.-M.
    ;
    Hossaert-McKey, Martine
    ;
    Benrey, Betty 
    Five microsatellite loci were isolated from the bruchid Acanthoscelides obvelatus Bridwell (Coleoptera: Bruchidae). Each locus was polymorphic, with the number of alleles ranging from two to 15. We found high levels of within-population variation at most loci, with heterozygosity ranging from 0.182 to 0.900. Cross-species amplification of these loci was tested in two other species of the genus Acanthoscelides, A. obtectus Say and A. argillaceus Sharp.
  • Publication
    Accès libre
    Horismenus species (Hymenoptera: Eulophidae) in a bruchid beetle parasitoid guild, including the description of a new species
    Hansson, Christer
    ;
    Aebi, Alexandre 
    ;
    Benrey, Betty 
    Four species of Horismenus (Hymenoptera: Eulophidae) associated with Acanthoscelides spp.(Coleoptera: Bruchidae), three of which are also associated with Phaseolus spp., are treated. One of the species, H. butcheri, is described as new and the remaining three species are redescribed. Allfour species are diagnosed in a key. A lectotype is designated for Holcopelte productus Ashmead.
  • Publication
    Accès libre
    The potential of native parasitoids for the control of Mexican bean beetles: A genetic and ecological approach
    Aebi, Alexandre 
    ;
    Shani, Tal
    ;
    Hansson, Christer
    ;
    Contreras-Garduno, Jorge
    ;
    Mansion, Guilhem
    ;
    Benrey, Betty 
    Bruchid beetles in the genus Zabrotes are important pests of field and stored beans all around the world and cause enormous economical losses in Mexico and Central America. Native parasitoids have been successfully used to suppress infestations by bruchid beetles in Africa, but few studies have assessed their potential to reduce seed damage in the New World and no successful biological control programs have been implemented, mainly due to the poor knowledge on their biology, systematics and ecology in this region. In this study, we used molecular tools to describe a new complex of three parasitoid species of bruchid beetles in the genus Horismenus, and investigated the level of gene flow and presence of ecotypes in this complex. We also examined the specific association between species of Horismenus and two sibling species of Zabrotes beetles, in order to evaluate their potential as biological control agents. Microsatellite data support the previous morphological description of three species, H. butcheri, H. missouriensis and H. depressus, but suggest some gene flow between H. missouriensis and H. depressus. Host-plant is shown to be the most important factor determining the ecological distribution of the two Zabrotes species, whereas altitude explains most of the distribution of the three Horismenus species. These results complement our understanding of this tritrophic system, providing a solid base for a potential biological control program using native parasitoids.
  • Publication
    Accès libre
    Microsatellite markers in a complex of Horismenus sp. (Hymenoptera: Eulophidae), parasitoids of bruchid beetles
    Aebi, Alexandre 
    ;
    Alvarez, N
    ;
    Butcher, R.D.J
    ;
    Hansson, C
    ;
    Risterucci, A.M
    ;
    Benrey, Betty 
    Parasitoids of the genus Horismenus (Hymenoptera: Eulophidae) are the main natural enemies of bruchid beetles that feed on several species of Phaseolus beans. Samples of Horismenus depressus, H. missouriensis and H. butcheri were collected from seeds of three Phaseolus species throughout Mexico to examine the impact of plant variability on the genetic structure of parasitoid populations. For this purpose, six microsatellite loci were isolated and characterized. These loci are of great interest in understanding the taxonomy of the genus Horismenus, the most important Eulophid genus in the Neotropics.