Location: Corn Insects and Crop Genetics ResearchTitle: The genetic structure of Asian corn borer, Ostrinia furnacalis, populations in China: Haplotype variance in Northern populations and potential impact on management of resistance to transgenic maize Author
|Kim, Kyung Seok|
Submitted to: Journal of Heredity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/22/2014
Publication Date: 7/13/2014
Citation: Li, J., Coates, B.S., Kim, K., Bourguet, D., Ponsard, S., Wang, Z., He, K. 2014. The genetic structure of Asian corn borer, Ostrinia furnacalis, populations in China: Haplotype variance in Northern populations and potential impact on management of resistance to transgenic maize. Journal of Heredity. 105(5):642-655. Interpretive Summary: The Asian corn borer (ACB), Ostrinia furnacalis, is a highly destructive insect pest of corn in China and Southeast Asia. Transgenic corn that express Bacillus thuringienis (Bt) toxins have been commercialized in the Philippines, but are in the process of registration in China. Delays in registration include questions of effective resistance management strategies that will delay the development of resistance within ACB populations. Concerns of potential ACB resistance have increased following reports of feeding on silks of transgenic corn that express the Bt toxin, Cry1Ac. Microsatellite and mitochondrial DNA markers were used to estimate the gene flow within and between ACB populations in China. Results showed that random mating may not occur within the ACB population, which was indicated by significant genetic differences between ACB the have a single mating generation per year with all other populations that have greater than one generation per year. These data are important for the evaluation of effectiveness of refuge strategies devised to delay the development of Bt resistance traits in the presence of reduced gene flow and non-random mating.
Technical Abstract: The Asian corn borer, Ostrinia furnacalis (Guenée), is a severe pest of cultivated maize that is endemic to the major production regions of China. Populations show phenotypic variation in obligatory or facultative diapause in response to selection within local environments, which affects the levels of season-long damage to crop plant and the tactics used for its control. Low genetic differentiation was show among samples from 34 collection sites across China (n = 1673) using variation at 6 nuclear microsatellite loci (ENA corrected global FST = 0.021; P-values > 0.05), whereas pairwise FST estimates showed significance among 60.8% of comparisons (P-values = 0.00089). Analysis of molecular variance (AMOVA) indicated geographic region, or diapause traits accounted for < 0.44% of the total genetic variation, which was corroborated by clustering of co-ancestries among genotypes using the program STRUCTURE. In contrast, a mitochondrial haplotype network clustered 4 distinct groups, where 70.5% of population samples with obligatory diapause traits were in group B. Populations with obligatory diapause were placed into unique clusters using Population Graph and Principal Component (PC) analyses, and showed significant differentiation with populations with facultative diapause traits ('ST = 0.366; P-values < 0.01). This study suggests that gene flow among O. furnacalis in China may be limited among geographically and topographically isolated regions, as well as between populations with different diapause traits. This genetic variation may be influenced by adaptation to local environmental effects or selection for diapause traits.