scholarly journals RNAi for Western Corn Rootworm Management: Lessons Learned, Challenges, and Future Directions

Insects ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 57
Author(s):  
Molly Darlington ◽  
Jordan D. Reinders ◽  
Amit Sethi ◽  
Albert L. Lu ◽  
Partha Ramaseshadri ◽  
...  
Keyword(s):  
Environmental Protection Agency ◽  
Management Strategies ◽  
Housekeeping Genes ◽  
Diabrotica Virgifera Virgifera ◽  
The United States ◽  
Western Corn Rootworm ◽  
Lessons Learned ◽  
Corn Rootworm ◽  
In Planta ◽  
Commercial Use

The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, is considered one of the most economically important pests of maize (Zea mays L.) in the United States (U.S.) Corn Belt with costs of management and yield losses exceeding USD ~1–2 billion annually. WCR management has proven challenging given the ability of this insect to evolve resistance to multiple management strategies including synthetic insecticides, cultural practices, and plant-incorporated protectants, generating a constant need to develop new management tools. One of the most recent developments is maize expressing double-stranded hairpin RNA structures targeting housekeeping genes, which triggers an RNA interference (RNAi) response and eventually leads to insect death. Following the first description of in planta RNAi in 2007, traits targeting multiple genes have been explored. In June 2017, the U.S. Environmental Protection Agency approved the first in planta RNAi product against insects for commercial use. This product expresses a dsRNA targeting the WCR snf7 gene in combination with Bt proteins (Cry3Bb1 and Cry34Ab1/Cry35Ab1) to improve trait durability and will be introduced for commercial use in 2022.

scholarly journals Resistance to Bt Maize by Western Corn Rootworm: Effects of Pest Biology, the Pest–Crop Interaction and the Agricultural Landscape on Resistance

Insects ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 136
Author(s):  
Aaron Gassmann
Keyword(s):  
Agricultural Landscape ◽  
Continuous Cultivation ◽  
Diabrotica Virgifera Virgifera ◽  
The United States ◽  
Western Corn Rootworm ◽  
Corn Rootworm ◽  
Agricultural Crop ◽  
Bt Maize ◽  
Bt Toxin ◽  
Resistance Evolution

The western corn rootworm, Diabrotica virgifera virgifera LeConte, is among the most serious pests of maize in the United States. Since 2003, transgenic maize that produces insecticidal toxins from the bacterium Bacillus thuringiensis (Bt) has been used to manage western corn rootworm by killing rootworm larvae, which feed on maize roots. In 2009, the first cases of field-evolved resistance to Bt maize were documented. These cases occurred in Iowa and involved maize that produced Bt toxin Cry3Bb1. Since then, resistance has expanded to include other geographies and additional Bt toxins, with some rootworm populations displaying resistance to all commercially available Bt traits. Factors that contributed to field-evolved resistance likely included non-recessive inheritance of resistance, minimal fitness costs of resistance and limited adult dispersal. Additionally, because maize is the primary agricultural crop on which rootworm larvae can survive, continuous maize cultivation, in particular continuous cultivation of Bt maize, appears to be another key factor facilitating resistance evolution. More diversified management of rootworm larvae, including rotating fields out of maize production and using soil-applied insecticide with non-Bt maize, in addition to planting refuges of non-Bt maize, should help to delay the evolution of resistance to current and future transgenic traits.

scholarly journals Survey of bacteria associated with western corn rootworm life stages reveals no difference between insects reared in different soils

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Dalton C. Ludwick ◽  
Aaron C. Ericsson ◽  
Lisa N. Meihls ◽  
Michelle L. J. Gregory ◽  
Deborah L. Finke ◽  
...  
Keyword(s):  
Pest Management ◽  
Life Stage ◽  
Management Strategies ◽  
Diabrotica Virgifera Virgifera ◽  
Western Corn Rootworm ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Corn Rootworm ◽  
Life Stages ◽  
Different Soils

Abstract Western corn rootworm (Diabrotica virgifera virgifera LeConte) is a serious pest of maize (Zea mays L.) in North America and parts of Europe. With most of its life cycle spent in the soil feeding on maize root tissues, this insect is likely to encounter and interact with a wide range of soil and rhizosphere microbes. Our knowledge of the role of microbes in pest management and plant health remains woefully incomplete, yet that knowledge could play an important role in effective pest management strategies. For this study, insects were reared on maize in soils from different locations. Insects from two different laboratory colonies (a diapausing and a non-diapausing colony) were sampled at each life stage to determine the possible core bacteriome. Additionally, soil was sampled at each life stage and resulting bacteria were identified to determine the possible contribution of soil to the rootworm bacteriome, if any. We analyzed the V4 hypervariable region of bacterial 16S rRNA genes with Illumina MiSeq to survey the different species of bacteria associated with the insects and the soils. The bacterial community associated with insects was significantly different from that in the soil. Some differences appear to exist between insects from non-diapausing and diapausing colonies while no significant differences in community composition existed between the insects reared on different soils. Despite differences in the bacteria present in immature stages and in male and female adults, there is a possible core bacteriome of approximately 16 operational taxonomic units (i.e., present across all life stages). This research may provide insights into Bt resistance development, improved nutrition in artificial rearing systems, and new management strategies.

scholarly journals Partial characterization of Bt resistance and the bacteriome of western corn rootworm

2018 ◽  
Author(s):  
◽  
Dalton C. Ludwick
Keyword(s):  
New Technologies ◽  
Management Strategies ◽  
Diabrotica Virgifera Virgifera ◽  
Western Corn Rootworm ◽  
Control Measures ◽  
Corn Rootworm ◽  
Diabrotica Barberi ◽  
The Usa ◽  
Diabrotica Virgifera Virgifera Leconte ◽  
Northern Corn Rootworm

Western corn rootworm (Diabrotica virgifera virgifera LeConte) and northern corn rootworm (Diabrotica barberi (Smith and Lawrence)) are major pests of maize in the USA. These pests have been managed with a variety of tactics over the last century. Both Diabrotica spp. have adapted to crop rotation in different ways in certain regions of the USA as well as to some of the insecticides targeted at them. D. v. virgifera has adapted to more of the chemical control measures and transgenic control methods. Discussed in this review are the challenges associated with managing both species, and how current management strategies might be combined and implemented to help manage damage from these species. Also, we discuss the potential for new technologies, such as RNA interference, to be used in the future.

EFFECTS OF AZADIRACHTIN ON THE WESTERN CORN ROOTWORM, DIABROTICA VIRGIFERA VIRGIFERA (LECONTE) (COLEOPTERA: CHRYSOMELIDAE)

1991 ◽  
Vol 123 (3) ◽  
pp. 707-710 ◽  
Author(s):  
Y.S. Xie ◽  
D. Gagnon ◽  
J.T. Arnason ◽  
B.J.R. Philogène ◽  
J.D.H. Lambert ◽  
...  
Keyword(s):  
United States ◽  
Diabrotica Virgifera Virgifera ◽  
The United States ◽  
Western Corn Rootworm ◽  
Crop Damage ◽  
Corn Rootworm ◽  
Diabrotica Virgifera ◽  
Corn Production ◽  
Main Method ◽  
Diabrotica Virgifera Virgifera Leconte

Corn rootworm (Diabrotica spp., Coleoptera: Chrysomelidae) is a serious pest insect of corn production. It is estimated that farmers in the United States have losses of over $1 billion each year as a result of crop damage and treatment costs for this pest (Metcalf 1986). Chemical control is the main method of suppressing corn rootworm populations and the amount of insecticide used against Diabrotica spp. is greater than for any other pests of corn in the United States (Suguiyama and Carlson 1985). The development of nontoxic and biodegradable alternatives to chemical insecticides is highly desirable.

scholarly journals Comparing Populations of Western Corn Rootworm (Coleoptera: Chrysomelidae) in Regions With and Without a History of Injury to Cry3 Corn

2020 ◽  
Vol 113 (4) ◽  
pp. 1839-1849
Author(s):  
Coy R St. Clair ◽  
Graham P Head ◽  
Aaron J Gassmann
Keyword(s):  
Management Strategies ◽  
Diabrotica Virgifera Virgifera ◽  
Western Corn Rootworm ◽  
Management Tool ◽  
Bt Corn ◽  
Corn Rootworm ◽  
Root Injury ◽  
Important Pest ◽  
Bacterium Bacillus ◽  
Management Tactics

Abstract Transgenic corn expressing insecticidal proteins derived from the bacterium Bacillus thuringiensis (Bt) is an important pest management tool. Western corn rootworm, Diabrotica virgifera virgifera LeConte, is a key pest of corn in the midwestern United States that has developed field-evolved resistance to all available Bt traits. The first Bt trait to be commercialized for management of rootworm was Cry3Bb1 in 2003, and field-evolved resistance appeared in 2009. In this study, we examined fields in counties where greater-than-expected injury to Cry3 (Cry3Bb1 or mCry3A) corn roots (>1 node) had previously been reported (problem counties) and counties where injury had not been reported (non-problem counties). Four to eight fields were sampled per county in 2015, 2016, and 2017 to quantify rootworm abundance, root injury, Cry3Bb1resistance, and rootworm management strategies. Rootworm abundance, root injury, and resistance to Cry3Bb1 did not differ between county types. Management tactics differed between county types, with problem counties growing more corn, using more soil insecticide, and growing more Cry34/35Ab1 corn. Additionally, a comparison of root injury to Bt and non-Bt corn within fields indicated that farmers derived an economic benefit from planting Bt corn to manage corn rootworm. Our results suggest that rootworm populations are similar between problem and non-problem counties in Iowa due to similar levels of selection pressure on Cry3 corn, but problem county fields have applied more management tactics due to previous rootworm issues in the area.

scholarly journals The Use of Insecticides to Manage the Western Corn Rootworm, Diabrotica virgifera virgifera, LeConte: History, Field-Evolved Resistance, and Associated Mechanisms

Insects ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 112 ◽  
Author(s):  
Lance J. Meinke ◽  
Dariane Souza ◽  
Blair D. Siegfried
Keyword(s):  
Diabrotica Virgifera Virgifera ◽  
The United States ◽  
Western Corn Rootworm ◽  
Cross Resistance ◽  
Corn Rootworm ◽  
Diabrotica Virgifera ◽  
Mechanisms Of Resistance ◽  
Pyrethroid Insecticides ◽  
Diabrotica Virgifera Virgifera Leconte ◽  
Over Time

The western corn rootworm, Diabrotica virgifera virgifera LeConte (Dvv) is a significant insect pest of maize in the United States (U.S.). This paper reviews the history of insecticide use in Dvv management programs, Dvv adaptation to insecticides, i.e., field-evolved resistance and associated mechanisms of resistance, plus the current role of insecticides in the transgenic era. In the western U.S. Corn Belt where continuous maize is commonly grown in large irrigated monocultures, broadcast-applied soil or foliar insecticides have been extensively used over time to manage annual densities of Dvv and other secondary insect pests. This has contributed to the sequential occurrence of Dvv resistance evolution to cyclodiene, organophosphate, carbamate, and pyrethroid insecticides since the 1950s. Mechanisms of resistance are complex, but both oxidative and hydrolytic metabolism contribute to organophosphate, carbamate, and pyrethroid resistance facilitating cross-resistance between insecticide classes. History shows that Dvv insecticide resistance can evolve quickly and may persist in field populations even in the absence of selection. This suggests minimal fitness costs associated with Dvv resistance. In the transgenic era, insecticides function primarily as complementary tools with other Dvv management tactics to manage annual Dvv densities/crop injury and resistance over time.

scholarly journals Binary Toxins from Bacillus thuringiensis Active against the Western Corn Rootworm, Diabrotica virgifera virgifera LeConte

2004 ◽  
Vol 70 (8) ◽  
pp. 4889-4898 ◽  
Author(s):  
James A. Baum ◽  
Chi-Rei Chu ◽  
Mark Rupar ◽  
Gregory R. Brown ◽  
William P. Donovan ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Insect Pest ◽  
Diabrotica Virgifera Virgifera ◽  
The United States ◽  
Western Corn Rootworm ◽  
Binary Toxin ◽  
Corn Rootworm ◽  
Diabrotica Virgifera ◽  
Crystal Proteins ◽  
Genes Encoding

ABSTRACT The western corn rootworm, Diabrotica virgifera virgifera LeConte, is a significant pest of corn in the United States. The development of transgenic corn hybrids resistant to rootworm feeding damage depends on the identification of genes encoding insecticidal proteins toxic to rootworm larvae. In this study, a bioassay screen was used to identify several isolates of the bacterium Bacillus thuringiensis active against rootworm. These bacterial isolates each produce distinct crystal proteins with approximate molecular masses of 13 to 15 kDa and 44 kDa. Insect bioassays demonstrated that both protein classes are required for insecticidal activity against this rootworm species. The genes encoding these proteins are organized in apparent operons and are associated with other genes encoding crystal proteins of unknown function. The antirootworm proteins produced by B. thuringiensis strains EG5899 and EG9444 closely resemble previously described crystal proteins of the Cry34A and Cry35A classes. The antirootworm proteins produced by strain EG4851, designated Cry34Ba1 and Cry35Ba1, represent a new binary toxin. Genes encoding these proteins could become an important component of a sustainable resistance management strategy against this insect pest.

scholarly journals Structural and functional insights into the first Bacillus thuringiensis vegetative insecticidal protein of the Vpb4 fold, active against western corn rootworm

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0260532
Author(s):  
Jean-Louis Kouadio ◽  
Meiying Zheng ◽  
Michael Aikins ◽  
David Duda ◽  
Stephen Duff ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Protective Antigen ◽  
Domain Architecture ◽  
Diabrotica Virgifera Virgifera ◽  
The United States ◽  
Western Corn Rootworm ◽  
Corn Rootworm ◽  
Insecticidal Proteins ◽  
Amino Terminal ◽  
Carbohydrate Binding Modules

The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, is a major maize pest in the United States causing significant economic loss. The emergence of field-evolved resistant WCR to Bacillus thuringiensis (Bt) traits has prompted the need to discover and deploy new insecticidal proteins in transgenic maize. In the current study we determined the crystal structure and mode of action (MOA) of the Vpb4Da2 protein (formerly known as Vip4Da2) from Bt, the first identified insecticidal Vpb4 protein with commercial level control against WCR. The Vpb4Da2 structure exhibits a six-domain architecture mainly comprised of antiparallel β-sheets organized into β-sandwich layers. The amino-terminal domains 1–3 of the protein share structural homology with the protective antigen (PA) PA14 domain and encompass a long β-pore forming loop as in the clostridial binary-toxB module. Domains 5 and 6 at the carboxyl-terminal half of Vpb4Da2 are unique as this extension is not observed in PA or any other structurally-related protein other than Vpb4 homologs. These unique Vpb4 domains adopt the topologies of carbohydrate-binding modules known to participate in receptor-recognition. Functional assessment of Vpb4Da2 suggests that domains 4–6 comprise the WCR receptor binding region and are key in conferring the observed insecticidal activity against WCR. The current structural analysis was complemented by in vitro and in vivo characterizations, including immuno-histochemistry, demonstrating that Vpb4Da2 follows a MOA that is consistent with well-characterized 3-domain Bt insecticidal proteins despite significant structural differences.

scholarly journals Development and improvement of artificial diets for larvae of Diabrotica species using multidimensional design space techniques

2018 ◽  
Author(s):  
◽  
Man P. Huynh
Keyword(s):  
Weight Gain ◽  
Artificial Diet ◽  
Diabrotica Virgifera Virgifera ◽  
The United States ◽  
Western Corn Rootworm ◽  
Corn Rootworm ◽  
Artificial Diets ◽  
Corn Root ◽  
Bt Toxins ◽  
Northern Corn Rootworm

The western corn rootworm (Coleoptera: Chrysomelidae; Diabrotica virgifera virgifera LeConte) and the northern corn rootworm (Coleoptera: Chrysomelidae; Diabrotica barberi Smith and Lawrence) are highly adaptive insect pests and have developed resistance to most possible management tactics in some regions. Transgenic maize hybrids, the latest control tools, which express insecticidal crystalline toxins from Bacillus thuringiensis (Bt) Berliner, have also faltered due to physiological adaptation of western corn rootworm populations. The United States Environmental Protection Agency has mandated insect resistance management plans for corn rootworms that have been directed toward monitoring the development of resistance to each of the Bt toxins. Toxicity bioassays using artificial diet have proven to be valuable for monitoring resistance to Bt toxins in corn rootworm populations. Currently, several proprietary diet formulations for western corn rootworm larvae that have been developed by each of the maize seed companies are used by industry and public researchers in toxicity bioassays to detect decreases in susceptibility of western corn rootworm populations to Bt proteins. No artificial diet has been developed specifically for northern corn rootworm larvae. Since differences in diet formulations can lead to different results in diet toxicity assays, it is impossible to make diet comparisons between toxicity assays using different artificial diets from individual companies and it may not be possible to determine an accurate picture of the test population's phenotype as it relates to Bt resistance. We report new diet formulations that support improved weight gain, larval development, and survival compared with current diets used in western corn rootworm and northern corn rootworm bioassays. The new formulations were created by using response surface modeling coupled with n-dimensional mixture designs to identify and optimize key ingredients based on integrated evaluation of several life history parameters (i.e., weight, molting, survival) while limiting contamination. The new rootworm formulations supported approximately 97% larval survival and molting and increased larval weight gain after 10 days of feedings compared to other diets used in western corn rootworm and northern corn rootworm bioassays rearing. These new formulations provide a standardized growth medium for western corn rootworm and northern corn rootworm larvae that will facilitate toxicity test comparisons conducted by different working groups and meets all regulatory requirements. We developed an improved diet formulation (WCRMO-1) for western corn rootworm (Chapter 2), which was the optimization of diet ingredients in the only published diet for western corn rootworm larvae. This formulation was also compatible for use with all current Bt proteins targeting western corn rootworm larvae. However, this formulation contains corn root powder, which is not available for purchase, limiting the practical use of the diets. We demonstrated that essential growth factors in corn roots that assist in western corn rootworm growth can be extracted suggesting substituting corn root powder with compounds identified from the extract may be possible (Chapter 3). An improved and accessible diet for western corn rootworm (WCRMO-2) that is comparable with all current diets for western corn rootworm larvae and without corn root powder was created by exploring and characterizing protein ingredients from plant, animal and yeast products (Chapter 4). Lastly, we developed the first artificial diet (NCRMO-1) for northern corn rootworm (Chapter 5) comprised of available ingredients that supports performance of northern corn rootworm larvae better than that of publicly available rootworm formulations.

scholarly journals Western Corn Rootworm (Diabrotica virgifera virgifera LeConte) in Europe: Current Status and Sustainable Pest Management

Insects ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 195
Author(s):  
Renata Bažok ◽  
Darija Lemić ◽  
Francesca Chiarini ◽  
Lorenzo Furlan
Keyword(s):  
Pest Management ◽  
Management Strategies ◽  
Diabrotica Virgifera Virgifera ◽  
Western Corn Rootworm ◽  
European Countries ◽  
Corn Rootworm ◽  
Diabrotica Virgifera ◽  
Research Activities ◽  
Diabrotica Virgifera Virgifera Leconte ◽  
The Eu

Western corn rootworm (WCR), or Diabrotica virgifera virgifera LeConte, became a very serious quarantine maize pest in Europe in the mid-1990s. Between 1995 and 2010, European countries were involved in international projects to share information and plan common research for integrated pest management (IPM) implementation. Since 2011, however, common efforts have declined, and an overview of WCR population spread, density, and research is in serious need of update. Therefore, we retained that it was necessary to (1) summarize the research activities carried out in the last 12 years in various countries and the research topics addressed, and analyze how these activities have contributed to IPM for WCR and (2) present the current distribution of WCR in the EU and analyze the current population levels in different European countries, focusing on different management strategies. A review of scientific papers published from 2008 to 2020, in addition to direct interviews with experts in charge of WCR management in a range of European countries, was conducted. Over the past 12 years, scientists in Europe have continued their research activities to investigate various aspects of WCR management by implementing several approaches to WCR control. A considerable amount of new knowledge has been produced, contributing to the development of pest management strategies applicable in EU farming systems. Among the 10 EU countries analyzed, there is no country reporting economic damage on a large scale. Thanks to intensive research leading to specific agricultural practices and the EU Common Agricultural Policy, there are crop-rotation-based solutions that can adequately control this pest avoiding insecticide use.

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