Ashley N. Dean

European corn borer, Ostrinia nubilalis (Lepidoptera: Crambidae), remains an important pest of corn and several other vegetable and field crops across North America despite substantial population declines following widespread adoption of Bacillus thuringiensis (Bt) plant-incorporated protectant (PIP) corn. Recent reports of field resistance to multiple Bt proteins in Canada and the United States highlight the need to reassess current management practices and reestablish active monitoring for this historically destructive species. This manuscript provides an updated synthesis of European corn borer biology, ecology, host range, injury patterns, and movement behavior, emphasizing traits that influence risk and management outcomes in modern production systems. We summarize current detection approaches, including pheromone trapping, degree-day models, and targeted scouting strategies. Management recommendations integrate cultural practices, abiotic mortality factors, biological control, chemical control, and PIP stewardship, with particular attention to resistance monitoring and refuge compliance. Collectively, these updates underscore the continued importance of European corn borer as a dynamic pest whose management requires coordinated surveillance, adherence to integrated pest management principles, and sustained trait stewardship to preserve the long-term efficacy of Bt technologies across North America.

Corn is one of the major commodities in the United States, and is grown for fuel, feed, and food around the world. Much of the production is centered in the Midwest, but corn is grown throughout the country and has a national production value of $91.7 billion. Because of the substantial national economic impact of corn production, as well as the profitability of individual farming operations, crop protection from pests is critical. Corn is most vulnerable during ear and kernel formation, and pest infestations during this time can have a substantial impact on grain quality and yield. Detecting pests is one of the most important components of integrated pest management, and regular scouting can allow farmers to make timely management decisions for pests in corn. However, farmers and crop consultants sometimes do not notice ear-feeding pests of corn until the fall, or near harvest, when pests are nearly done feeding or have vacated the ear. When this happens, it can be difficult to diagnose the problem, which can be important for assessing management tactics that were used in the field during the current growing season or making decisions for the following growing season based on pest activity in the field. This article provides profiles of common ear-feeding pests, with written descriptions and photographs of typical injury to corn ears for those pests.

Chemical defoliation of seed corn production fields accelerates seed maturation and desiccation and expedites seed harvest. Early seed harvest is important to minimize the risk of frost damage while in the field. This newly adopted seed production practice also allows seed companies to plan harvest and manage dryer space more efficiently. However, premature defoliation may interfere with the migration of oil bodies within embryo cells during desiccation and affect seed germination and vigor. The objective of this study was to investigate the effect of chemical defoliation on the migration patterns of oil bodies within embryo cells during desiccation. Chemically defoliated and non-defoliated plants from five commercial hybrid seed corn fields were sampled in 2014 and 2015. Whole ears with husks were harvested before and after defoliant application at 600 g H₂O kg⁻¹ fresh weight (fw), and weekly thereafter until seed reached approximately 300–350 g H₂O kg⁻¹ fw. Ten embryos extracted from center-row seeds were fixed to stop metabolic processes, then sliced, processed, and photographed using scanning transmission electron microscopy. The oil bodies within embryo cells followed normal migration patterns according to seed moisture content, regardless of defoliation treatment. Seed germination and vigor were verified and were not significantly affected by defoliation. Chemical defoliation is a viable production practice to accelerate seed corn desiccation and to manage harvest and seed dryer availability more efficiently without negatively affecting seed germination and vigor.

Corn, Zea mays L. (Cyperales: Poaceae), production is essential to Iowa’s economy and provides food, feed, and fuel beyond the state. Farmers face a number of challenges in corn production, including insect pests, and understanding farmers’ perceptions and concerns is critical for extension personnel to provide adequate and relevant programming. The Iowa State University Agriculture and Natural Resources Crops Team conducted a survey of Iowa farmers and agribusiness professionals during the 2019–2020 extension season. The goal was to understand farmer perceptions of corn pests and whether farmers experienced challenges with resistance to Bt traits or insecticides. Additionally, we aimed to realize farmers’ confidence in developing resistance management plans and discussing those needs with their input suppliers and advisors. Our survey revealed that northern corn rootworm, Diabrotica barberi Smith & Lawrence (Coleoptera: Chrysomelidae), was the pest of greatest concern across the state. People were generally more concerned about belowground Bt trait performance than aboveground traits, though only 12% of respondents reported Bt trait failure for corn rootworms. In general, people were not concerned about the performance of seed treatments or soil- or foliar-applied insecticides. Farmers generally felt very confident in developing a resistance management plan and discussing their needs with their advisors. The results of this survey will be used to target extension programming throughout the state and increase confidence for farmers and agribusiness employees to discuss resistance management plans together.

BACKGROUND: The profitability of farming varies based on factors such as a crop's market value, input costs and occurrence of resistant pests, all capable of altering the value of pest management tactics in an integrated pest management program. We provide a framework for calculating expected yield and expected net revenue of pest management scenarios, using the soybean aphid (Aphis glycines) as a case study. Foliar insecticide and host‐plant resistance are effective management tactics for preventing yield loss from soybean aphid outbreaks; however, pyrethroid‐resistant aphid populations pose a management challenge for farmers. We evaluated eight scenarios relevant to soybean aphid management in Iowa with varying probabilities of aphid outbreaks and insecticide‐resistant aphids occurring.RESULTS: Our equation suggests that insecticide use is profitable when the probability of an aphid outbreak is ≥29%, and soybean production will become more costly with increasing probability of pyrethroid‐resistant aphids. If farmers continue to use pyrethroids, they will not experience financial consequences from pyrethroid‐resistant aphids until the chance of insecticide resistance is 48%. Aphid‐resistant varieties provided consistent yield and offered the highest net revenue under all conditions.CONCLUSION: This framework can be used for other crop–pest systems to evaluate the profitability of management tactics and investigate how resistance impacts revenue for farmers. Including the cost of resistance in crop budgets can help farmers and agronomic consultants comprehend these impacts and enhance decision‐making to increase revenue and curb resistance development.

We wanted to understand whether short-term learning could occur during Extension presentations and used an immediate feedback tool to find out. Applying the immediate feedback tool, we asked multiple-choice questions prior to delivering a presentation and repeated them at the end to assess how well the information was delivered to and received by the audience. The immediate feedback tool let participants know whether they understood the information presented. Results indicated that adults were receptive to immediate feedback and that closed-ended questions can provide reliable evaluation data. Participants showed significant learning with the tool, which has broad applicability in Extension.