Introgression between divergent corn borer species in a region of sympatry: implications on the evolution and adaptation of pest arthropods

Authors: WANG, YANGZHOU - Jilin Agricultural University; KIM, KYUNG SEOK - Iowa State University; GUO, WENCHAO - Xinjiang Agricultural University; LI, QIYUN - Jilin Agricultural University; ZHANG, YUNYUE - Jilin Agricultural University; WANG, ZHENYING - Chinese Academy Of Agricultural Sciences; Coates, Brad

Submitted to: Molecular Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/26/2017
Publication Date: 12/26/2017
Citation: Wang, Y., Kim, K.S., Guo, W., Li, Q., Zhang, Y., Wang, Z., Coates, B.S. 2017. Introgression between divergent corn borer species in a region of sympatry: implications on the evolution and adaptation of pest arthropods. Molecular Ecology. 26(24):6892-6907. https://doi.org/10.1111/mec.14387.
DOI: https://doi.org/10.1111/mec.14387

Interpretive Summary: Pest insects feed upon cultivated crop plants worldwide and the development of resistance to control practices used by producers is a major concern. An ARS researcher and international collaborators demonstrate that two closely related species of corn borer and exchange genes (known as gene flow) within a region of the world there they coexist. This occurs despite nearly 3.3 million years since the corn borer species shared a common ancestor, and in that time having developed novel communications systems involved in mating. Research further predicted that gene flow was biased for movement of gene from one species into the other. These findings have major implications for global agriculture by showing flow may be prevalent among species, and could impact the spread of resistance traits across species boundaries. This research is of interest to university, government and private industry stakeholders concerned about the stainability of insect pest control.

Technical Abstract: The Asian corn borer, Ostrinia furnacalis, and European corn borer, O. nubilalis (Lepidoptera: Crambidae) cause damage to cultivated maize in spatially distinct geographies, and have evolved divergent hydrocarbons as the basis of sexual communication. The Yili area of Xinjiang Province China represents the only known region where these two corn borer species co-occur. Larvae collected from maize plants at 11 locations in Xinjiang Province, and genotyped using high throughput single nucleotide polymorphism (SNP) and microsatellite makers. Material lineages and species assignment was assessed by direct sequencing of mitochondrial cytochrome c oxidase subunit I and II haplotypes. Haplotype diversity indices demonstrated a high degree of variation between species, and analogously shown for genotypic data. Hybridization was predicted in 0.85% of samples wherein an O. nubilalis maternal haplotype coincided with an O. furnacalis genotype at the highly divergent odorant receptor 4 locus. Furthermore, historical introgression was predicted through shared co-ancestry among SNP genotypes only at locations in the Yili area, whereas Xinjiang Province populations in which only O. furnacalis haplotypes were detected showed no analogous co-ancestries. Our direct detection of putative hybrids and historical evidence of introgression defines Yili area as a hybrid zone between species in normal ecological interactions, and furthermore might indicate that adaptive traits could spread even between seemingly divergent species through vertical transmission. Results of this study indicate there may be a continuum in degrees of reproductive isolation between Ostrinia species, and that the elegance of distinct and complete speciation based on modifications to the pheromone communication might be reconsidered.