Melanaphis sorghi (Theobald) (Hemiptera: Aphididae), commonly called the sorghum aphid, is an invasive pest of sorghum (Sorghum bicolor) (L.) in North America. It was first observed in 2013 along the Gulf Coastal Plains ecoregion of Texas, Louisiana (USA), and Mexico, where it quickly established itself as an economically important pest within a few years. This ecoregion contains an established complex of aphid natural enemies, including both predators and parasitoids. In the decade since its invasion, indicators of increased suppression observed across six years and five locations from south to north Texas were as follows: (1) aphid abundances trending downwards across the years, (2) overall natural enemy abundances trending upwards during the same time period, and (3) a key parasitoid and coccinellid species increasing in dominance. Two key taxa, Aphelinus nigritus (Howard) (Hymenoptera: Aphelinidae) and six species of coccinellids (Coleoptera: Coccinellidae), were likely responsible for the majority of the pest’s suppression. In light of these findings, the importance of monitoring and stewarding natural enemies of invasive insect pests is discussed as part of a comprehensive strategy to measure and reduce the impact of a pest invasion in large-scale agroecosystems.

Harmonia axyridis is an invasive beetle (Coleoptera: Coccinellidae), native to Asia, that has established on four continents beyond its native range and was first observed in South Africa in 2001. Using microsatellite data and a comprehensive geographic coverage of international (17 locations) and South African (14 locations) beetle samples, we inferred the source of colonists invading South Africa and the beetle’s movement within the country. Genetic structure analyses suggest that this species’ populations in South Africa are derived from admixture between beetles originating from eastern North America (which acted as a bridgehead population) and another population not directly sampled in our study. Genetic admixture prior its invasion into South Africa, along with the possibility of multiple introductions from the bridgehead population, may explain the high genetic diversity estimates for South African H. axyridis (H_E = 0.582–0.625) compared to beetles from the native range (H_E = 0.440–0.636). Harmonia axyridis appear to be frequently exchanging genetic material across South Africa, with no clear genetic structure between sampled locations. However, evidence of weak isolation-by-distance within South Africa suggests that beetles are dispersing less frequently between locations that are furthest apart. This study supports previous findings on global invasion pathways in this species but provides new insights in the context of the invasion in South Africa. We highlight how mixing of distinct lineages from divergent origins prior to the invasion into South Africa has augmented genetic diversity in the region. The high dispersal rates and large effective population sizes inferred from genetic markers suggest that slowing the spread or reducing population abundances of the species in South Africa will be challenging without an integrated, multi-faceted management approach.

The cotton fleahopper (Pseudatomoscelis seriatus (Reuter)) is an early-season hemipteran plant bug pest of cotton. In transgenic cotton cultivars, Bt event Mpp51Aa2 (Cry51Aa2) affects some other plant bug species (Hemiptera: Miridae) (we henceforth use the common terminology, stating that these cultivars have the ThryvOn trait). Field experiments were conducted in Corpus Christi, Texas, USA, to evaluate the responses of four cotton cultivars with and without the ThryvOn trait to cotton fleahopper infestations, comparing them with early-season foliar insecticide applications of flupyradifurone. Naturally occurring cotton fleahopper populations rose to the economic threshold midway through the first four weeks of squaring, when cotton plants are most sensitive to feeding injury, in 2024 and later in the same period in 2025. Flupyradifurone application significantly reduced adult and nymph abundance, resulting in reduced square abscission (2025) and yield protection that was consistent across cultivars in 2024 but more variable in 2025. Cultivars expressing the ThryvOn trait exhibited modest and variable reductions in adult cotton fleahopper abundance (~10–30%), occasionally benefiting from reduced square abscission but not protected yield. The open boll ratio, used to assess maturity delay, was not affected by cultivar or cotton fleahopper pressure. These results indicate that ThryvOn cultivars may provide limited supplemental benefits but do not replace or enhance the effectiveness of flupyradifurone for cotton fleahopper management.

The availability of spatial data on agricultural land cover, such as the cropland data layer (CDL) developed by the US Department of Agriculture, has facilitated areawide pest management study. The CDL is derived from a raster-based process that primarily uses data layers of satellite images to produce a georeferenced land cover classification. Here, we considered (i) the extent that adjustments at the pixel level to address land cover misclassifications of the CDL changed simple composition (percent cover) and more complex composition (diversity) and configuration metrics, and (ii) if changes were sensitive to spatial scale (10 km2 and ≤ 3 km2 areas) and land cover (three crops and 3 seminatural lands). Next, we considered (iii) whether the landscape metrics derived from the original CDL as modified by 2 adjustment methods affected outcomes of a stepwise regression to consider selected landscape metrics as indicators of cotton fleahopper (Pseudatomoscelis seriatus) and sorghum aphid (Melanaphis sorghi) abundance. Changes in the metrics resulted from applying 2 adjustments (majority filter and manual) to extracted buffers taken from the CDL, with indication of overcorrection using the manual method. Selected metrics were sensitive to landscape structure (8 of 26 two-way interactions of adjustment, scale, and land cover were significant). In regression exercises, configuration metrics of cotton, sorghum, and grassland were the main metrics selected, and fewer metrics were selected when derived from adjusted buffers. Overall, the majority filter adjustment showed moderate sensitivity to scale and land cover and appeared to clarify landscape structure (particularly configuration of land covers) that influences two cotton and sorghum pests. Attention to data quality and downstream analysis for areawide pest management study is advisable going forward for this CDL and likely other land cover data products now available worldwide.

Infection of corn by the pathogen Aspergillus flavus can result in the contamination of the grain with aflatoxin, a potent, regulated mycotoxin. A. flavus has high genetic diversity, even within a single field, but it is unknown if the population is homogeneous among the different matrices of the corn agroecosystem or whether there are discernable subpopulations. We collected isolates of A. flavus from two sites for 2 years from soil, grain, corn silks, and Helicoverpa zea moths and larvae. This collection of more than 1,000 isolates of A. flavus were screened and characterized based on aflatoxigenic potential, sclerotial morphotype, and 17 simple sequence repeat (SSR) markers. The collection from the Corpus Christi, Texas, study site had a higher frequency of aflatoxigenic isolates than the collection from Stoneville, Mississippi. The genotype of a commercially available biocontrol isolate of A. flavus was present at both study sites but was five times more abundant at Stoneville, Mississippi, than at Corpus Christi, Texas. SSR-based population genetics indicated that the A. flavus populations collected from various matrices were not differentiated and that there appeared to be significant gene flow among the populations within each site.