scholarly journals Characterization of Corn Root Factors to Improve Artificial Diet for Western Corn Rootworm (Coleoptera: Chrysomelidae) Larvae

2019 ◽  
Vol 19 (2) ◽  
Author(s):  
Man P Huynh ◽  
Elisa J Bernklau ◽  
Thomas A Coudron ◽  
Kent S Shelby ◽  
Louis B Bjostad ◽  
...  
Keyword(s):  
Artificial Diet ◽  
Positive Impact ◽  
Larval Growth ◽  
Dry Weight ◽  
Diabrotica Virgifera Virgifera ◽  
Extraction Methods ◽  
Western Corn Rootworm ◽  
Corn Rootworm ◽  
Corn Root ◽  
Corn Roots

Abstract The western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), is an important economic pest of maize (Zea mays L.) in North America and Europe. Previous efforts to formulate an artificial diet for western corn rootworm larvae highlighted an important role of corn root powder, which had a significant positive impact on several larval developmental traits. Unfortunately, this ingredient is not available for purchase. Toward the goal of developing an artificial diet for western corn rootworm larvae with all ingredients readily accessible, we conducted research to isolate essential growth factors for larval development from corn root powder to improve the performance of diet without corn root powder. For all experiments, multiple life history parameters (survival, weight, and molting) were recorded from 15-d diet bioassays. Corn roots may contain factors that assist in larval growth, but some of these factors were not fully extracted by methanol and remained in the extracted root. Methanolic extracts significantly increased molting to second instar, but did not significantly increase survival, dry weight, or molting to third instar, suggesting the primary corn root substituents affecting these factors cannot be extracted or other extraction methods may be required to extract the essential factors from corn roots. We showed that whole corn root powder was best when used in combination with all the other nutrient sources in the published western corn rootworm formulation. Corn root powder made from proprietary seed and Viking seed has similar value.

scholarly journals Comparison of Six Artificial Diets for Western Corn Rootworm Bioassays and Rearing

2018 ◽  
Vol 111 (6) ◽  
pp. 2727-2733 ◽  
Author(s):  
Lisa N Meihls ◽  
Man P Huynh ◽  
Dalton C Ludwick ◽  
Thomas A Coudron ◽  
B Wade French ◽  
...  
Keyword(s):  
Artificial Diet ◽  
Extended Period ◽  
Dry Weight ◽  
Diabrotica Virgifera Virgifera ◽  
Larval Survival ◽  
Western Corn Rootworm ◽  
Fourth Instar ◽  
Corn Rootworm ◽  
Artificial Diets ◽  
Testing Susceptibility

Abstract The western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), is considered the most important maize (Zea mays L.) pest in the U.S. Corn Belt. Bioassays testing susceptibility to Bacillus thuringiensis Berliner (Bt) and other toxins of corn rootworm larvae often rely on artificial diet formulations. Successful bioassays on artificial diet for corn rootworm have sometimes been challenging because of microbial contamination. Toward the long-term goal of developing a universal artificial diet for western corn rootworm larvae, we compared larval survival, dry weight, and percentage of molt in 10-d bioassays from six current diets of which we were aware. In addition, as part of longer term rearing efforts, we recorded molting over an extended period of development (60 d). Six different artificial diets, including four proprietary industry diets (A, B, C, and D), the first published artificial diet for western corn rootworm (Pleau), and a new diet (WCRMO-1) were evaluated. Western corn rootworm larval survival was above 90% and contamination was 0% on all diets for 10 d. Diet D resulted in the greatest dry weight and percentage molting when compared with the other diets. Although fourth-instar western corn rootworm larvae have not been documented previously (only three instars have been previously documented), as many as 10% of the larvae from Diet B molted into a fourth instar prior to pupating. Overall, significant differences were found among artificial diets currently used to screen western corn rootworm. In order for data from differing toxins to be compared, a single, reliable and high-quality western corn rootworm artificial diet should eventually be chosen by industry, academia, and the public as a standard for bioassays.

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.

ROLE OF 2,4-DIHYDROXY-7-METHOXY-1,4-BENZOXAZIN-3-ONE (DIMBOA) IN THE RESISTANCE OF MAIZE TO WESTERN CORN ROOTWORM, DIABROTICA VIRGIFERA VIRGIFERA (LECONTE) (COLEOPTERA: CHRYSOMELIDAE)

1990 ◽  
Vol 122 (6) ◽  
pp. 1177-1186 ◽  
Author(s):  
Y.S. Xie ◽  
J.T. Arnason ◽  
B.J.R. Philogène ◽  
J.D.H. Lambert ◽  
J. Atkinson ◽  
...  
Keyword(s):  
Growth Parameters ◽  
Adult Emergence ◽  
Dry Weight ◽  
Diabrotica Virgifera Virgifera ◽  
Head Capsule ◽  
Western Corn Rootworm ◽  
Corn Rootworm ◽  
Diabrotica Virgifera ◽  
Fresh Weight ◽  
Growing Seasons

Abstract2,4-Dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), the major hydroxamic acid present in corn root, was studied for its effects on western corn rootworm, Diabrotica virgifera virgifera (LeConte). Exogenously applied DIMBOA caused mortality in western corn rootworm larvae feeding on fresh corn roots. The LC50 (lethal concentration for 50% mortality) value (fiducial limits) was 153 ppm (108–209) and the LC90 value was 917 ppm (560–2297). The deleterious effects of DIMBOA on western corn rootworm larvae possibly are due to both feeding deterrence and toxicity. In a replicated pot trial during two growing seasons, two corn lines developed by Agriculture Canada from CIMMYT collections, ITR 3872 with high DIMBOA content in roots, and NTR-2 Ger. 4042 with low DIMBOA content in roots, were evaluated for resistance to western corn rootworm larvae. The results indicated that the high DIMBOA line (but not the low DIMBOA line) stressed western corn rootworm larvae to produce inferior adults based on the measurement of adult emergence number, adult weight, and adult head-capsule width. The effect of western corn rootworm on both corn lines with different DIMBOA levels was measured based on plant growth parameters including plant height, stem thickness, plant fresh weight, root fresh weight, plant dry weight, and root dry weight. ITR 3872 (high DIMBOA) showed significantly less damage than NTR-2 Ger. 4042 (low DIMBOA) in almost all plant parameters measured. The results suggest that DIMBOA may in some instances contribute to the resistance of corn to western corn rootworm larvae.

scholarly journals Development of an improved and accessible diet for western corn rootworm larvae using response surface modeling

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Man P. Huynh ◽  
Bruce E. Hibbard ◽  
Michael Vella ◽  
Stephen L. Lapointe ◽  
Randall P. Niedz ◽  
...  
Keyword(s):  
Response Surface ◽  
Diabrotica Virgifera Virgifera ◽  
Larval Survival ◽  
Surface Modeling ◽  
Western Corn Rootworm ◽  
Larval Performance ◽  
Response Surface Modeling ◽  
Corn Rootworm ◽  
Corn Root ◽  
Significant Difference

Abstract The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, is an important pest of maize (Zea mays L.). Published WCR diets contain corn root powder, which is not available for purchase, thereby limiting the practical use of diets containing this ingredient. We applied response surface modeling combined with mixture designs to formulate a WCR diet that does not require corn root powder. We developed the new formulation by systematically exploring eight protein ingredients from animal, plant, and yeast sources based on simultaneous evaluation of three life history parameters (weight, molting, and survival). This formulation (WCRMO-2) without corn root powder supported approximately 97% of larval survival and successful molting. Larval weight gain after 10 days of feeding on WCRMO-2 was 4-fold greater than that of larvae feeding on the current best published WCR diet. Additionally, there was no significant difference in these larval performance traits when larvae were reared on WCRMO-2 and the best proprietary WCR diet. A commercial version of WCRMO-2 was tested and found to perform comparably for these traits. These improvements met our goal of a diet comprised of available ingredients that supports performance of WCR larvae equal to or better than publicly available formulations and proprietary formulations.

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 Detection of alternative splicing in Diabrotica virgifera virgifera LeConte, in association with Bt resistance using RNA-seq and PacBio Iso-Seq

2020 ◽  
Author(s):  
Zixiao Zhao ◽  
Christine G. Elsik ◽  
Bruce E. Hibbard ◽  
Kent S. Shelby
Keyword(s):  
Alternative Splicing ◽  
Matrix Protein ◽  
Diabrotica Virgifera Virgifera ◽  
Western Corn Rootworm ◽  
Corn Rootworm ◽  
Diabrotica Virgifera ◽  
Rna Seq ◽  
Bt Resistance ◽  
Bt Toxins ◽  
Alternatively Spliced

AbstractBackgroundAlternative splicing is one of the major mechanisms that increases transcriptome diversity in eukaryotes, including insect species that have gained resistance to pesticides and Bt toxins. In western corn rootworm (Diabrotica virgifera virgifera LeConte), neither alternative splicing nor its role in resistance to Bt toxins has been studied.ResultsTo investigate the mechanisms of Bt resistance we carried out single-molecule real-time (SMRT) transcript sequencing and Iso-seq analysis on resistant, eCry3.1Ab-selected and susceptible, unselected, western corn rootworm neonate midguts which fed on seedling maize with and without eCry3.1Ab for 12 and 24 hours. We present transcriptome-wide alternative splicing patterns of western corn rootworm midgut in response to feeding on eCry3.1Ab-expressing corn using a comprehensive approach that combines both RNA-seq and SMRT transcript sequencing techniques. We found that 67.73% of multi-exon genes are alternatively spliced, which is consistent with the high transposable element content of the genome. One of the alternative splicing events we identified was a novel peritrophic matrix protein with two alternative splicing isoforms. Analysis of differential exon usage between resistant and susceptible colonies showed that in eCry3.1Ab-resistant western corn rootworm, expression of one isoform was significantly higher than in the susceptible colony, while no significant differences between colonies were observed with the other isoform.ConclusionOur results provide the first survey of alternative splicing in western corn rootworm and suggest that the observed alternatively spliced isoforms of peritrophic matrix protein may be associated with eCry3.1Ab resistance in western corn rootworm.

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