Ecological network characteristics of the functional groups of epigaeic arthropod in arable land with different field margin types

Species diversity and functional group characteristic of epigaeic arthropod community is key to maintaining the diversity and stability of farmland ecosystems. Exploring the effects of semi-natural habitats, such as field margins, on the diversity of natural enemies and utilizing the spillover effects of natural enemies in semi-natural habitats and farmland is beneficial for strengthening the protection of natural enemies, which is of great significance in formulating sustainable pest control strategies and optimizing the allocation of agricultural landscape. However, the ecological network characteristics of epigaeic arthropod functional groups in arable land with different field margin types are currently unclear. A systematic understanding of species distribution patterns and interactions among species in arable land with different field margin types is the basis for determining the population occurrence of insect herbivores and natural enemies. To optimize the structure of non-tillage habitats and rationally distribute agricultural landscape, we used the trap method to investigate the community compositon and the functional groups (natural enemies, herbivores, and neutral) of epigaeic arthropods in the adjacent arable lands of five field margin types (paved road, irrigation canal and ditch, woodland, dirt road, and grassland) in Changtu County, Liaoning Province. Variance analysis, community ordination, and ecological networks were used to analyze the differences in arthropod community distribution, functional group diversity, and ecological network symbiosis in adjacent arable land with the margins of different vegetation characteristics, margin width, and human disturbance intensity. The results showed that the species diversity of epigaeic arthropods decreased from the margin to the interior of arable land, and there were significant differences in species diversity between 0 m and 15 m, 30 m in arable land with margin of paved road and significant differences in species diversity between 0 m and 30 m in arable land with margin of woodland, dirt road, and grassland. The diversity of natural enemy groups was higher in woodland and grassland. The epigaeic arthropod community structure was more complex in margins with higher plant diversity. The ecological network of the epigaeic arthropod community showed a positive correlation, the network structure of the epigaeic arthropod community with woodland and grassland margins was more stable, and the entire network system was more resistant to external changes. The internal network connectivity of grasslands, ditches, and woodlands was strong and robust. The internal ecological network of arable land with paved roads and dirt roads was unstable. In general, the more complex the community structure of the field margin vegetation is, the more stable are the margin habitat conditions. In addition, the more complex the ecological network structure between natural enemies and herbivores in adjacent arable land is, the more beneficial it is to maintain the high diversity of natural enemies and improve the biological control function. Therefore, strengthening the vegetation community structure of field margins, such as the construction of an appropriate vegetation community structure and margin width, can improve the ecological network relationship between epigaeic arthropod communities, which is important for pest control and ecosystem stability. For future agricultural landscape construction, we should not only enhance biodiversity but also explore the ecological network relationship and co-occurrence law among species.