Spodoptera frugiperda has caused serious economic damage to various crops. Entomopathogenic nematodes (EPNs) can be used as biological control agents for many pests, including lepidopteran insects. In this study, 218 soil samples were collected from 46 sites in Guangxi, and EPNs were detected in 15 samples. The ITS region of the rDNA gene was used for the molecular identification of isolated nematodes. In total, four and eleven identified populations belonged to Heterorhabditis and Oscheius, respectively. A series of bioassays were conducted to examine the virulence of EPN isolates from Guangxi to control the larvae and pupae of S. frugiperda. The mortality of the third-instar larvae caused by EPNs was concentration dependent. The same dose of EPNs was used to control the third and sixth-instar larvae of S. frugiperda, and the virulence was lower in the sixth-instar larvae. S. frugiperda pupae were treated with different EPNs strains, and the adult eclosion rate of the treated group was significantly lower than that of the sterile water control group (93.3%). Therefore, EPNs could significantly inhibit the eclosion of S. frugiperda pupae. This study provides important information for the biological control of S. frugiperda with EPNs.

The black soil layer has undergone substantial degradation in Northeast China, and it is crucial to adopt reasonable tillage measures to prevent black soil degradation. Organic amendment strategies provide an effective solution for mitigating nutrient loss in black soil; meanwhile, there is still a lack of systematic investigation into their impact on soil microbial communities. Thus, we carried out a five-year field experiment from 2020 to 2025 in Jilin Province. Four organic amendment strategies were set up: conventional tillage (CT); straw returning (SR); straw returning + inorganic fertilizer (SRI); and straw returning + inorganic fertilizer + organic fertilizer (SRIO). Furthermore, we investigated the effects of organic materials on soil properties and microbial communities during the maize seedling stage. The results showed that SR significantly increased the relative abundance of Bradyrhizobium, Tausonia and Coprinopsis, while SRI led to a 140.3% increase in Nocardioides. In SRIO treatment, Gaiella and Fusarium were significantly enriched by 103.9% and 142.5%, respectively. Moreover, SR treatment significantly decreased the fungal Shannon and Simpson index by 18.8% and 4.2%, respectively. Organic matter, alkali nitrogen, and available potassium were the primary environmental factors shaping both bacterial and fungal community structures. Additionally, the co-occurrence network suggested that straw returning promoted more diverse interactions among soil bacterial and fungal communities. Our study highlights the potential of organic amendment strategies in enhancing black soil nutrients, as well as their important role in maintaining soil microbial function and stability.

The dissemination of antibiotic resistance genes (ARGs) in agricultural soils poses a potential environmental risk, and soil amendment practices may influence this process by altering microbial communities and mobile genetic elements (MGEs). In this study, we investigated the effects of corn straw (CS), manure (ME), and biochar (MR) on the abundance and distribution of soil ARGs and MGEs, together with the mechanisms underlying these responses. The results showed that CS increased the abundance of endogenous ARGs, with oqxB and AAC(3)-Ic increasing by 48.1% and 74.5%, respectively, while also activating transposable elements such as istA1. ME introduced high-risk exogenous MGEs, including Tn916 and qacEdelta. In contrast, MR suppressed most MGEs. Significant correlations were observed between Pseudomonadota and Actinomycetota and both ARGs and MGEs. Moreover, each treatment enriched specific key genera, including Lysobacter under CS and Pseudomonas under ME. Thereby shaping distinct patterns of resistance dissemination. Structural equation modeling revealed that microbial communities directly regulated the dissemination of ARGs and MGEs, whereas soil properties, particularly available potassium and moisture content, indirectly affected ARG distribution through their effects on microbial communities. Overall, the risk of resistance dissemination followed the order ME > CS > MR. These findings provide a scientific basis for optimizing soil amendment strategies in agricultural systems.