Ivair Valmorbida

The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), causes economically significant damage to soybean, Glycine max, in the north central region of the United States. Knockdown resistance (kdr) to field-applied rates of pyrethroids in A. glycines is associated with target site mutations in Domain II Segment IV-VI (DIISIV-VI) of the voltage-gated sodium channel subunit h1 (vgsc-h1). Between 2021 and 2023, aphids were collected from 10 commercial fields across northern Iowa at different timepoints and sub-field regions relative to the application of a pyrethroid. We also collected aphids from 4 suction traps in northern Iowa, designed to capture aphids migrating between winter and summer host plants. None of the field populations reached the economic threshold of 250 aphids per plant or decreased significantly following application of a pyrethroid. Nineteen vgsc-h1 genotypes with 1 or more target site mutation each were detected among 99.9% of the 1955 field collected aphids. The proportion of these 19 genotypes changed significantly between timepoints relative to the application of a pyrethroid, with the frequency of aphids with greater than 1 mutation increasing after a pyrethroid application. All aphids collected in suction traps also had genotypes encoding target site mutations. These results suggest that 4 mutations associated with pyrethroids resistance are highly prevalent among A. glycines infesting soybean in northern Iowa, may confer different levels of survival to in-field selection and have spread readily across the landscape in response to strong in field selection. Continued genetic monitoring information will be important to inform growers of the efficacy of their A. glycines management decisions.

Leafhoppers are major vectors of plant pathogens that depend on microbial symbionts to exploit nutrient-poor diets. However, most studies of leafhopper-associated microbiota have focused on a limited number of taxa leaving the genomic diversity, and ecological organization of these microbial communities poorly understood. Here, we generated a genome-resolved global leafhopper microbiome resource by integrating genome-resolved metagenomics from 171 leafhopper species across 11 subfamilies and 13 countries, including the first microbiomes characterized from Arctic leafhoppers. De novo assembly and genome reconstruction generated 272 non-redundant microbial genomes and 18.6 million non-redundant genes, substantially expanding the known microbial diversity associated with Cicadellidae, including several previously undescribed bacterial lineages. Comparative analyses revealed a recurrent modular microbiome architecture composed of: (i) a conserved core of obligate nutritional symbionts; (ii) a heterogeneous layer of secondary symbionts; and (iii) a dynamic pool of environmentally acquired bacteria. While obligate symbionts remained highly conserved across divergent hosts, secondary and environmental taxa varied substantially among species and regions, suggesting repeated acquisition shaped by ecological filtering rather than host phylogeny alone. Comparative analyses between the specialist corn leafhopper and the polyphagous aster leafhopper further showed that closely related vectors can maintain conserved ancestral symbionts while harboring distinct accessory microbiomes. Arctic populations contained unique microbial assemblages with annotated functions associated with cold tolerance, oxidative stress, and reproductive manipulation. This work establishes a genome-resolved framework for understanding microbiome evolution in insect vectors and provides a resource for testing the potential roles of microbiome variation in host adaptation, pathogen ecology, and sustainable pest management.

Stink bugs (Hemiptera: Pentatomidae) are among the most economically important pests of soybean, Glycine max (L.) Merrill, in Missouri, where management relies largely on broad-spectrum insecticides. Despite evidence that parasitoids contribute to stink bug suppression in other regions, information on parasitism in Missouri soybeans remains limited. We conducted a 2-yr survey (2024 to 2025) in 316 soybean fields in Missouri to quantify parasitism of adult stink bugs by tachinid flies (Diptera: Tachinidae). In addition, stink bug egg masses were sampled for the presence of egg parasitoids once in 152 soybean fields across the state, and weekly at three locations during the 2025 growing season. Overall, 7.4% of adult stink bugs were parasitized, with higher parasitism observed in males than in females; adult parasitism also varied significantly between years, with 10.4% in 2024 and 6.5% in 2025. Egg parasitism was detected in 9.4% of egg masses and 4.1% of individual eggs collected statewide. Season-long monitoring showed significant differences among locations. Parasitism differed among stink bug species, with eggs of the Brown complex (Euschistus spp.) exhibiting significantly higher parasitism rates than those of Chinavia hilaris (Say) (Hemiptera: Pentatomidae). The egg parasitoids Trissolcus edessae Fouts (Hymenoptera: Scelionidae) and Telenomus podisi Ashmead (Hymenoptera: Scelionidae) were found parasitizing stink bug eggs. Together, these results provide the first comprehensive assessment of stink bug parasitism in Missouri soybeans and establish a baseline for evaluating parasitoids’ contribution to suppressing stink bug populations.

Stink bugs (Hemiptera: Pentatomidae) are among the most economically important insect pests of soybeans in Missouri. However, the community composition, abundance, spatial patterns, and phenology remain poorly understood across different ecoregions in the state. We conducted a statewide survey of stink bugs in commercial soybean fields during the 2024 and 2025 growing seasons to address this gap. Sweep net sampling was conducted at the field edge and interior of 316 soybean fields. A total of 2,718 stink bugs, representing nine species, were collected. Chinavia hilaris (Say) was the dominant species, accounting for >80% of all individuals, followed by Euschistus variolarius (Palisot de Beauvois) and Euschistus servus (Say) (10.55% and 5.89%, respectively). Halyomorpha halys (Stål) was detected at low frequencies in 5 locations. The abundance of C. hilaris was significantly greater at field edges than in interiors and differed among ecoregions, whereas the abundance of the Euschistus complex showed regional differences that varied between the growing seasons. Species diversity differed among ecoregions, with the highest Shannon diversity observed in the Salem Plateau. Stink bug abundance was low during vegetative and early reproductive stages, followed by rapid population increases beginning at R5 and peaking at R6, driven primarily by the presence of nymphs. These results provide the first comprehensive, statewide assessment of stink bug community and spatial distribution in Missouri soybeans that can be used to optimize scouting timing and improve management decisions.

Global population growth has increased the demand for food production and, therefore, for higher crop yields, especially for soybean, which is one of the most cost-effective and affordable sources of high-quality protein for animal and human nutrition. This frequently leads to an overuse of traditional chemical insecticides to maximize yields, thereby triggering negative side effects. However, both consumers and governments around the world demand a reduction in chemical insecticides in agriculture. To address this challenge, pest control must be guided by proper adoption of economic thresholds (ETs), which indicate the most appropriate time to initiate control in the crop. Despite the well-documented science behind ETs, farmers have questioned the adoption and reliability in a search for higher production, highlighting the importance of reviewing this topic. Thus, based on the available literature, the role of ETs in optimizing insecticide application in soybean production around the world is herein discussed, highlighting the importance of their adoption to mitigate the overuse of chemicals by emphasizing examples from the major world soybean producers (Brazil, the United States of America, Argentina, and China). In conclusion, this review highlights the importance of changing farmers’ perception that using more insecticide is necessary to guarantee higher yields. On the contrary, only by the adoption of ETs within Integrated Pest Management is it possible to obtain better pest management and, consequently, reduce yield loss. Despite some limitations related to their simplicity and risks of adoption, the use of ETs improves soybean sustainability and farmers’ profits while benefiting the agroecosystem. For future directions, their complexity should increase to more realistically represent agroecosystems; in addition, tools should be developed (computer programs and smartphone apps using, for instance, artificial intelligence) to translate this complexity into easy-to-adopt ETs.

Global population growth underscores the increasing demands for food production, and therefore, for higher crop yields, especially in soybean, as the cheapest source of protein for animal and human nutrition. This scenario frequently leads to overuse of traditional chemical insecticides to maximize yields, thereby triggering adverse side effects. However, both consumers and governments around the world have been demanding reduction of chemical insecticides in agriculture. To address this challenge, pest control must be guided by proper adoption of economic thresholds (ETs), which indicate the most appropriate time to initiate insecticide applications. Despite the well-documented science behind ETs, not only its adoption but also its reliability has been questioned by farmers in a search for higher production, highlighting the importance of reviewing this topic. Thus, this review discusses, based on the available literature, the role of ETs to optimize insecticide application in soybean production, highlining the importance of their adoption to mitigate the overuse of chemicals. In Brazil, the major soybean producer in the world, not only did growers who adopted ETs to control pests in soybean reduce the amount of pesticides required, but also production costs associated with pest control, while achieving greater yields than conventional producers. The use of ETs improves soybean sustainability and farmers profit while benefitting the agroecosystem.

Soybean, Glycine max (L.) Merrill, is usually grown on a large scale, with pest control based on chemical insecticides. However, the overuse of chemicals has led to several adverse effects requiring more sustainable approaches to pest control. Results from Integrated Pest Management (IPM) employed on Brazilian soybean farms indicate that adopters of the technology have reduced insecticide use by approximately 50% relative to non-adopters, with yields comparable to or slightly higher than those of non-adopters. This reduction can be explained not only by the widespread use of Bt soybean cultivars across the country but also by the adoption of economic thresholds (ETs) in a whole Soybean-IPM package, which has reduced insecticide use. However, low refuge compliance has led to the first cases of pest resistance to Cry1Ac, thereby leading to the return of overreliance on chemical control and posing additional challenges for IPM practitioners. The recent global agenda for decarbonized agriculture might help to support the adoption of IPM since less chemical insecticides sprayed over the crops reduces CO₂-equivalent emissions from its application. In addition, consumers’ demand for less pesticide use in food production has favored the increased use of bio-inputs in agriculture, helping mitigate overdependence of agriculture on chemical inputs to preserve yields. Despite the challenges of adopting IPM discussed in this review, the best way to protect soybean yield and preserve the environment remains as IPM, integrating plant resistance (including Bt cultivars), ETs, scouting procedures, selective insecticides, biological control, and other sustainable tools, which help sustain environmental quality in an ecological and economical manner. Soon, those tools will include RNAi, CRISPR-based control strategies, among other sustainable alternatives intensively researched around the world.

Dectes stem borer, Dectes texanus LeConte, is native to North America and is an economically important pest of sunflower and soybean across the US Dectes stem borer reached the status of an economical pest of sunflower and soybean during the 1970s. But this impact was often isolated and did not affect the entire production acres of these crops. In recent years, some states, including Iowa, Kansas, Minnesota, and South Dakota have observed an increase in Dectes stem borer pressure in soybean. Although the sunflower acreage varies by state, infestations of Dectes stem borer are common and may affect a large proportion of plants. In most soybean-producing states, severe Dectes stem borer infestations are sporadic but infestations that are not economical are common. The larvae feed on the central pith core of the host plant stem, and their girdling behavior can cause pre-harvest lodging that results in yield loss. Stem feeding can also cause 0% to 17% yield loss in soybean but causes negligible yield loss in sunflower. This document reviews the existing knowledge on Dectes stem borer ecology, biology, and management in soybean and sunflower. Emerging issues of this insect pest are discussed. It specifically focuses on developing integrated management tools to reduce insecticide selection pressure and promote economic management.

The economic threshold for defoliating insects during the reproductive stages of soybean varies among US states, from 15% to 25%. Defoliation estimation is made by visually inspecting the soybean canopy. However, there is variation among individual estimates, resulting in over- and underestimations of defoliation that might lead to improper spray decisions. Growers, consultants, and extension personnel are usually responsible for insecticide decisions, but their ability to estimate defoliation has not been documented. We surveyed 303 growers, consultants, extension personnel, as well as other occupations. We asked them to estimate defoliation based on trifoliate photographs. We also asked growers and consultants about the amount of area they typically grow soybeans and if they scout for defoliation or not. We hypothesized that low levels of defoliation would be easier to estimate compared to intermediate level of defoliation, that people with different backgrounds would estimate defoliation differently, and that growers who scouted their fields would better estimate defoliation compared to those who did not. We analyzed the data using multinomial logistic regression. Estimates were more correct for low levels compared to intermediate levels of defoliation. Estimates were not different depending on occupations. Growers who scout their fields better estimate defoliation compared to those who do not. Our results highlight the importance of experience for more accurate visual estimations of soybean defoliation and point out the need for reference tools to aid estimates of thresholds above 20% defoliation.

Soybean is usually grown at large scales, with pest control based on insecticides. However, the overuse of chemicals has led to several adverse effects. Thus, integrated pest management (IPM) is the best way to protect yield through integrating different pest control tools, based on plant resistance (including Bt cultivars), adoption of economic thresholds (ETs), scouting procedures, use of selective insecticides, biological control, and other sustainable tools, which help maintain environmental quality in an ecological and economical manner. Soon, those tools will also include RNAi, CRISPR based control strategies, among other sustainable alternatives. In Brazil, results from the Soybean-IPM Program indicate that adopters of the technology have reduced insecticide use by approximately 50% relative to non-adopters, with yields comparable to or slightly higher than those of non-adopters. This reduction can be explained not only by the widespread adoption of Bt soybean varieties across the country but also by the adoption of ETs in Soybean-IPM, which has reduced insecticide use, thereby increasing natural biological control in the agroecosystem. However, low refuge compliance has led to the first cases of pest resistance to Cry1Ac, thereby growing reliance on chemical control and posing an additional challenge for integrated pest management practitioners. The obstacles to adopting IPM programs for commodity crops, such as soybean, may be mitigated by recent economic incentives within the new global agenda for decarbonized agriculture and the increase of bioinputs available in the Brazilian market. Such incentives can support the broader adoption of IPM, thereby reducing dependence on chemical inputs to achieve high yields.