Landscape genetic analyses reveal host association of mitochondrial haplotypes in the Asian corn borer, Ostrinia furnacalis

Crop expansion often leads to high pest pressure. These pests may have fitness trade-offs related to host use, and some host-associated genotypes may benefit and increase in frequency. However, evidence concerning the effect of host availability on spatial distribution and frequency of mitochondrial haplotypes is scarce. We studied genetic variation of the Asian corn borer, Ostrinia furnacalis (Guenée), across a large area during 2 years (2016 and 2017). Mitochondrial sequence data were obtained from 530 individuals collected from 79 locations in Shandong Province, China. In total, 155 haplotypes were found based on the combined cytochrome oxidase subunit 1 (COI) and COII genes. Three haplotypes (H2, H12, and H23) were dominant, whereas most of the other haplotypes occurred in low frequency. A haplotype network showed that the 155 haplotypes can be grouped into three clusters. Haplotype clusters seemed to be randomly distributed. The frequency of H12 (in Cluster 1) was positively correlated with maize crop proportion, but negatively correlated with other crops (primarily vegetables, oilseed crops, and cotton) at all spatial scales (1-, 3-, and 5-km radius). Cluster 2 had haplotype H23, and this cluster was negatively correlated with semi-natural habitats. Cluster 3 had no dominant haplotype and was not affected by landscape factors. We conclude that H12 may be a maize-associated haplotype. Further study is needed to verify the possibility that the carriers of this haplotype may possess some fitness trade-offs. Our study highlights the importance of host availability in O. furnacalis haplotype distribution and frequency.