Influence of voltine ecotype and geographic distance on genetic and haplotype variation in the Asian corn borer

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

Submitted to: Ecology and Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/2020
Publication Date: 7/9/2021
Citation: Wang, Y., Kim, K., Li, Q., Zhang, Y., Wang, Z., Coates, B.S. 2021. Influence of voltine ecotype and geographic distance on genetic and haplotype variation in the Asian corn borer. Ecology and Evolution. 11(15):10244-10257. https://doi.org/10.1002/ece3.7829.
DOI: https://doi.org/10.1002/ece3.7829

Interpretive Summary: Species of corn borer are major pests of maize which can cause significant levels of crop damage resulting in reduced yields and profits among producers. Populations of corn borer show differences in the duration of dormancy during the winter, which changes the number of reproductive cycles per year. These traits are determined by both genetics and local environmental conditions. While populations of corn borer with either one or two mating generations per year can exist in the same location, it is unclear how much mating period overlap allows genetic exchange between populations. Using mitochondrial DNA and 257 genomic DNA markers, an ARS researcher in an international collaboration estimated the level of genetic differences between corn locations that had either one or two reproductive cycles per year, and locations with corn borer populations with mixed reproductive cycles. Data analysis showed that mitochondrial DNA variation was greatest between pure corn borer populations that differed in the number of reproductive cycles per year. High levels of variation was also found at 11 genomic DNA markers. These results indicate that there is reduced genetic exchange between corn borer populations with different reproductive cycles, which may influence the movement of gene(s) causing resistance to insecticidal toxins. These data will be of interest to regulators, and university, government, and industry scientists interested in the insect pest population dynamics and the potential for the movement of genes between corn borer with differing annual generation number.

Technical Abstract: Diapause is an adaptive dormancy strategy by which arthropods endure extended periods of adverse climatic conditions. Seasonal variation in larval diapause initiation and duration in the Asian corn borer, Ostrinia furnacalis, influences adult mating generation number (voltinism) across local environmental conditions. Degree of mating period overlap between sympatric voltinism ecotypes influences hybridization level, but impact on O. furnacalis population genetic structure and evolution of divergent adaptive phenotypes remains uncertain. Genetic differentiation was estimated between voltinism ecotypes collected from 8 locations in Jilin Province, China [3 single generation (univoltine), 3 two generation (bivoltine), and 2 sympatric locations] in 2014. Bayesian and phylogenetic clustering partitioned mitochondrial cytochrome c oxidase subunit I (COI) haplotypes mostly into groups corresponding to historically uni- or bivoltine population origins, whereas samples from sympatric locations were interspersed between voltinism-specific clusters. Additionally, analyses of single nucleotide polymorphism (SNP) genotype data implicate voltinism, as opposed to geographic distance, as a factor contributing to differentiation among sample site. Temporal analysis of SNP genotypes from a sympatric location showed significant variation between adult moths collected within non-overlapping periods corresponding to bivoltine and univoltine flights. Regardless, only 11 of 257 SNP loci were predicted to be under selection and contribute > 72% of the total genomic divergence, suggesting population genetic homogenization except at loci in proximity to factors responsible for locally adaptive or voltinism-specific traits. These findings suggest that divergent voltinism ecotype-specific traits and mitochondrial haplotypes may be maintained in allopatric as well as sympatric areas despite relatively high rates of nuclear gene flow.