Differences in oviposition behaviour of two sympatric sibling species of the genus Ostrinia
Auteurs : Malausa (Thibaut), Pélissie (Benjamin), Pélissier (Colette), Piveteau (Vanessa), Ponsard (Sergine) et Bourguet (Denis)
Année de publication : 2008
Publication : Bulletin of entomological Research
Volume :
98
Fascicule : 2
Pagination : 193-201
Résumé :
Changes in host preferences are thought to be a major Source of genetic divergence between phytophagous insect taxa. In western Europe, two sympatric taxa, O. nubilalis (the European corn borer) and O. scapulalis, feed mainly on maize and hop or mugwort, respectively. These two species may have diverged without geographic isolation after a host shift of ancestral populations onto maize or another cultivated species (e.g. sorghum). A previous study using inbred laboratory strains revealed that the two species differ in their oviposition choices in maize-mugwort tests. We sampled four natural populations in France (two of each taxon) and tested their oviposition behaviour toward four of their main host plant species: maize, sorghum, mugwort and hop. O. nubilalis females showed a very high preference for laying their eggmasses on maize, whereas O. scapulalis females displayed a more balanced range of preferences. O. nubilalis females were attracted slightly to sorghum, suggesting that this plant is an accidental, rather than a regular and ancestral host plant of O. nubilalis. One important result arising from this study is the significant proportion of eggs laid by both Ostrinia species on hop. This may explain why some stands of hop are sometimes not only infested by O. scapulalis but also by O. nubilalis larvae, a situation preventing assortative mating based on microallopatry. Hence, further studies must be conducted to see whether the host preference in the genus Ostrinia might be linked to assortative mating by a mechanism that is not mediated by the host plant/Having expanded for about thirty years, the Marbled Fritillary (Brenthis daphne) was observed for the first time in 2007 in the north France (region Nord [long dash] Pas-de-Calais) and more exactly in Avesnois (Trelon territory). It is possible that the observation of this nice butter will be the beginnings of a soon settling of this species in the Nord [long dash] Pas-de-Calais