title: 'Becoming a species by becoming a pest' or how two maize pests of the genus Ostrinia possibly evolved through parallel ecological speciation events.
abstract: New agricultural pest species attacking introduced crops may evolve from pre-existing local herbivores by ecological speciation, thereby becoming a species by becoming a pest. We compare the evolutionary pathways by which two maize pests (the Asian and the European corn borers, ACB and ECB) in the genus Ostrinia (Lepidoptera, Crambidae) probably diverged from an ancestral species close to the current Adzuki bean borer (ABB). We typed larval Ostrinia populations collected on maize and dicotyledons across China and eastern Siberia, at microsatellite and mitochondrial loci. We found only two clusters: one on maize (as expected) and a single one on dicotyledons despite differences in male mid-tibia morphology, suggesting that all individuals from dicotyledons belonged to the ABB. We found evidence for migrants and hybrids on both host plant types. Hybrids suggest that field reproductive isolation is incomplete between ACB and ABB. Interestingly, a few individuals with an 'ABB-like' microsatellite profile collected on dicotyledons had 'ACB' mtDNA rather than 'ABB-like' mtDNA, whereas the reverse was never found on maize. This suggests asymmetrical gene flow directed from the ACB towards the ABB. Hybrids and backcrosses in all directions were obtained in no-choice tests. In laboratory conditions, they survived as well as parental strain individuals. In Xinjiang, we found ACB and ECB in sympatry, but no hybrids. Altogether, our results suggest that reproductive isolation between ACB and ABB is incomplete and mostly prezygotic. This points to ecological speciation as a possible evolutionary scenario, as previously found for ECB and ABB in Europe.
authors.affiliation: Centre de Biologie pour la Gestion des Populations (CBGP), UMR INRA-IRD-CIRAD-Montpellier SupAgro, Campus International de Baillarguet, 34988, Montferrier-sur-Lez Cedex, France.
authors.forename: Denis
authors.initials: D
authors.lastname: Bourguet
authors.affiliation: UMR 5174 EDB (Laboratoire Evolution & Diversité Biologique), Université de Toulouse, ENFA, 118 route de Narbonne, F-31062, Toulouse, France.|UMR 5174 EDB, CNRS, Université Paul Sabatier, F-31062, Toulouse, France.|State Key Laboratory for the Biology of the Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, No.2 West Yuanmingyuan Road, Beijing, 100193, China.|UMR 5175, CNRS, Centre d'Ecologie Fonctionnelle et Evolutive (CEFE), 1919 route de Mende, Montpellier Cedex 05, 34293, Montpellier, France.
authors.forename: Sergine
authors.initials: S
authors.lastname: Ponsard
authors.affiliation: Centre de Biologie pour la Gestion des Populations (CBGP), UMR INRA-IRD-CIRAD-Montpellier SupAgro, Campus International de Baillarguet, 34988, Montferrier-sur-Lez Cedex, France.
authors.forename: Rejane
authors.initials: R
authors.lastname: Streiff
authors.affiliation: Centre de Biologie pour la Gestion des Populations (CBGP), UMR INRA-IRD-CIRAD-Montpellier SupAgro, Campus International de Baillarguet, 34988, Montferrier-sur-Lez Cedex, France.
authors.forename: Serge
authors.initials: S
authors.lastname: Meusnier
authors.affiliation: Centre de Biologie pour la Gestion des Populations (CBGP), UMR INRA-IRD-CIRAD-Montpellier SupAgro, Campus International de Baillarguet, 34988, Montferrier-sur-Lez Cedex, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Audiot
authors.affiliation: UMR 5174 EDB (Laboratoire Evolution & Diversité Biologique), Université de Toulouse, ENFA, 118 route de Narbonne, F-31062, Toulouse, France.|UMR 5174 EDB, CNRS, Université Paul Sabatier, F-31062, Toulouse, France.|State Key Laboratory for the Biology of the Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, No.2 West Yuanmingyuan Road, Beijing, 100193, China.|School of biological technology, Xi'an University of Arts and Science, No.168 South Taibai Road, Xi'an, Shaanxi Province, 710065, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.affiliation: State Key Laboratory for the Biology of the Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, No.2 West Yuanmingyuan Road, Beijing, 100193, China.
authors.forename: Zhen-Ying
authors.initials: ZY
authors.lastname: Wang
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D002678:Chimera; D002681:China; D016000:Cluster Analysis; D003433:Crosses, Genetic; D004272:DNA, Mitochondrial / Q000235:genetics; D005060:Europe; D051456:Gene Flow; D017344:Genes, Insect; D049810:Genetic Speciation; D005838:Genotype; D008297:Male; D018895:Microsatellite Repeats; D008957:Models, Genetic; D009036:Moths / Q000235:genetics*; D060047:Reproductive Isolation; D017422:Sequence Analysis, DNA; D003313:Zea mays
chemical_list: D004272:DNA, Mitochondrial
keywords: Ostrinia furnacalis; Ostrinia nubilalis; Ostrinia scapulalis; ecological speciation; microsatellites; mitochondrial DNA