Résultat de la recherche
Microsatellite markers in a complex of Horismenus sp. (Hymenoptera: Eulophidae), parasitoids of bruchid beetles
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.
Horismenus species (Hymenoptera: Eulophidae) in a bruchid beetle parasitoid guild, including the description of a new species
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.
The potential of native parasitoids for the control of Mexican bean beetles: A genetic and ecological approach
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.