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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. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fertilization F72 kg N/ha increased fungi diversity in maize experimental field. • Maize recruit different associated fungi than soil, by altering network complexity. • Core genera play an important role for nitrogen utilization in maize plants. • Endophytic fungi are valuable natural based solutions to improve crop fertilizer management. Endophytic mycobiomes are an integral part of crops in agricultural systems. Fertilization is a conventional practice to improve agricultural crops and may alter the mycobiomes of soil and plant systems. In agroecosystems, Nature Based Solutions (NBS) are key strategies for agricultural suitability. Investigating mycobiomes under N flux can provide fundamental data for constructive NBS strategies. In this study, the effects of nitrogen (N) fertilizer treatments on fungal compositions of the soil-maize systems were systematically investigated in field experiments at six N rates (F0, F72, F126, F180, F234, F280 kg N/ha) in northern China. Meta-omics amplicon sequencing of the internal transcribed spacer (ITS) region was employed to study community dynamics, network correlation, metabolic functional assemblies, abundance patterns and core fungi. This study found that fungal communities were significantly higher at 72 kg N/ha compared with control and other treatments. Network topology increased in maize fungi (R2 = 0.69) but decreased in the soil (R2 = 0.51). Abundances of carbon–nitrogen metabolizing functional genes (Ure , AMT, gdhA and GDH) were significantly correlated with maize fungal communities and were assembled by stochastic processes. Additionally, the relative abundance of Ascomycota (67.26 %) was dominant in the soil, whereas Basidiomycota (61. 73 %) prevailed in maize samples at 72 kg N/ha. Moreover, Sporidiobolus , Alternaria , Fusarium , and Penicillium served as conserved core genera and were positively correlated with NH 4 +-N mg/kg, NO 2 –-N mg/kg and NO 3 –-N mg/kg, and pH components. Furthermore, selective genera were tested and confirmed to increase the growth rate and nitrogen utilization in maize. The study highlights the promising role of associated endophytes as Nature-Based Solution for optimizing fertilization to improve crop production in maize-agroecosystem. [ABSTRACT FROM AUTHOR]