Helicoverpa armigera (Hübner) is one of the most important agricultural pests in the world. This historically Old World species was first reported in Brazil in 2013 and has since spread throughout much of South America and into the Caribbean. Throughout North America, H. armigera surveys are ongoing to detect any incursions. Each trap is capable of capturing hundreds of native Helicoverpa zea (Boddie). The two species cannot be separated without genitalic dissection or molecular methods. A ddPCR assay is currently used to screen large trap samples, but this equipment is relatively uncommon and expensive. Here, we optimized a newly designed assay for accurate and repeatable detection of H. armigera in bulk samples across both ddPCR and less costly, and more common, real-time PCR methods. Improvements over previously designed assays were sought through multiple means. Our results suggest bulk real-time PCR assays can be improved through changes in DNA extraction and purification, so that real-time PCR can be substituted for ddPCR in screening projects. While ddPCR remains a more sensitive method for detection of H. armigera in bulk samples, the improvements in assay design, DNA extraction, and purification presented here also enhance assay performance over previous protocols.

The effect of agricultural practices on soil bacterial communities is not constant and depends a lot on the climatic context, changes in the soil characteristics, land use, and agricultural strategy. Thus, knowledge about how different land use systems in the Cerrado influence the diversity and taxonomic structure of microbial communities under the same soil type remains limited. In this context, the objective of this work was to analyze and compare the bacterial communities of Cerrado soil under two different land use systems (cover crop and potato cultivation) and in a neighboring native Cerrado area. For this, we used high-throughput amplicon sequencing of 16S rRNA genes (metabarcoding) to characterize the bacterial community at different taxonomic levels in a native Cerrado area, in a potato crop area, and in an area with cover crops. Our data indicated significant impacts on soil physicochemical properties and enzymatic activity, which directly reflect the dynamics of bacterial communities. The three bacterial phyla with the highest relative abundance in the three areas were Proteobacteria, Actinobacteriota, and Acidobacteriota. At the taxonomic class level, small variations were observed among areas, while at the amplicon sequence variant (ASV) level, these variations were more pronounced. The alpha diversity indices showed that the bacterial communities among the areas are rich and diverse. Bray–Curtis and Jaccard distance-based PCoA demonstrated an overlap of bacterial communities present in the cover crop area with the native Cerrado area and separation from the potato cultivation area. The in silico prediction demonstrated that the native Cerrado area presented the highest values of functional diversity of the soil bacterial community compared to the others. Thus, our results provide a holistic view of how different land use systems in the Cerrado can influence the taxonomic and functional diversity of soil bacterial communities.

Understanding how agricultural soil management affects soil fungal communities is essential for assessing the resilience of biodiversity hotspots such as the Brazilian Cerrado. In this study, we characterized fungal community structure across three contrasting land-use systems within the same agricultural landscape: a native Cerrado remnant, a cover-cropping system, and a spatially isolated potato monoculture field. The soil’s chemical and enzymatic characteristics differed from one another and were clustered by area. However, the same pattern was not observed for the fungal community. Alpha-diversity indices did not differ significantly among sites, although native Cerrado soils showed slightly higher richness and evenness. Beta-diversity analyses based on Bray–Curtis and Jaccard distances, supported by NMDS, ANOSIM, beta-dispersion, and PERMANOVA, indicated no significant compositional differences among communities. Core-mycobiota analysis identified 157 shared ASVs, including genera such as Fusarium, Cladosporium, Chrysosporium, Trichoderma, and Clonostachys. As a preliminary assessment based on a limited spatial design and sequencing-based inference, these findings should be interpreted with caution. These results underscore the need for further research on the mechanisms driving fungal dispersal, edge effects, and the long-term impacts of agricultural land-use on fungal diversity and ecological integrity in the Cerrado.