scholarly journals Evidence of Resistance to Cry34/35Ab1 Corn by Western Corn Rootworm (Coleoptera: Chrysomelidae): Root Injury in the Field and Larval Survival in Plant-Based Bioassays

2016 ◽  
Vol 109 (4) ◽  
pp. 1872-1880 ◽  
Author(s):  
Aaron J. Gassmann ◽  
Ram B. Shrestha ◽  
Siva R. K. Jakka ◽  
Mike W. Dunbar ◽  
Eric H. Clifton ◽  
...  
Keyword(s):  
Larval Survival ◽  
Western Corn Rootworm ◽  
Corn Rootworm ◽  
Root Injury

Competition of Transgenic Volunteer Corn with Soybean and the Effect on Western Corn Rootworm Emergence

Weed Science ◽  
2012 ◽  
Vol 60 (2) ◽  
pp. 193-198 ◽  
Author(s):  
P. Marquardt ◽  
C. Krupke ◽  
W. G. Johnson
Keyword(s):  
Yield Loss ◽  
Larval Survival ◽  
Western Corn Rootworm ◽  
Growth And Yield ◽  
Corn Rootworm ◽  
Soybean Yield ◽  
Emergence Traps ◽  
Volunteer Corn ◽  
Corn Plants ◽  
The Impact

Glyphosate-resistant (GR) volunteer corn has emerged as a problematic weed in corn:soybean rotational systems, partly because of the rapid increase in adoption of corn hybrids that contain traits for both glyphosate and insect resistance. Volunteer GR corn can decrease soybean yields. The objectives of this study were to quantify the impact of volunteer corn on soybean growth and yield and determine how volunteer corn densities affect western corn rootworm (WCR) emergence. Volunteer corn seed was hand-planted at targeted densities of 0.5, 2, 4, 8, 12, and 16 seeds m−2at soybean planting and 21 d after planting to evaluate both early- and late-emerging cohorts. WCR emergence was assessed with the use of field emergence traps placed over individual corn plants in the 0.5- and 16-plants-m−2plots in 2008 and 2009. In 2010, WCR emergence traps were also placed over individual and clumped volunteer corn plants at densities of two and eight plants m−2. Soybean yield reductions ranged from 10 to 41% where early-emerging volunteer corn densities ranged from 0.5 to 16 plants m−2. No soybean yield loss occurred with the late-emerging cohort of volunteer corn. Twice as many adult WCRs emerged from a single volunteer corn plant growing at densities of 8 and 16 plants m−2, compared with plots containing 0.5 and 2 plants m−2. These results demonstrate that controlling volunteer corn will not only prevent soybean yield loss, but also may reduce the risk of WCR larval survival after exposure to Bt (Bacillus thuringiensisBerliner derived) corn.

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 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 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.

EVALUATION OF INFRARED THERMOMETRY AS A NON-DESTRUCTIVE METHOD TO DETECT FEEDING ON CORN ROOTS BY THE WESTERN CORN ROOTWORM (COLEOPTERA: CHRYSOMELIDAE)

1993 ◽  
Vol 125 (4) ◽  
pp. 643-655 ◽  
Author(s):  
A.W. Schaafsma ◽  
G.H. Whitfield ◽  
T.J. Gillespie ◽  
C.R. Ellis
Keyword(s):  
Grain Yield ◽  
Diabrotica Virgifera Virgifera ◽  
Kernel Weight ◽  
Western Corn Rootworm ◽  
Corn Rootworm ◽  
Diabrotica Virgifera ◽  
Infrared Thermometry ◽  
Root Injury ◽  
Crop Maturity ◽  
Non Destructive

AbstractInfrared thermometry was investigated as a diagnostic tool to detect root injury in corn caused by feeding of the western corn rootworm, Diabrotica virgifera virgifera LeConte. Plots were infested with 50–1000 eggs per plant, and the study was conducted over 2 years. Differences (P < 0.05) in canopy temperatures were detected in severely infested plots in 6 out of 13 days and 7 out of 11 days on which measurements were made during the period of feeding by rootworm larvae in 1989 and 1990, respectively. Temperature differences between the air and leaves from infested plants were never greater than 3.5 °C and usually occurred within ± 1 °C. Feeding by rootworm larvae at infestation levels of less than 200 eggs per plant could not be detected with infrared thermometry. Above densities of 200 eggs per plant, increases in canopy temperatures corresponded with increases in the level of infestation with rootworm eggs, and with reduced plant height, and lower grain yield. Losses in grain yield due to rootworm infestation were manifested through smaller cobs and fewer seeds per cob. Kernel weight was not affected by rootworm feeding. Crop maturity was delayed at infestation levels of 1000 eggs per plant.Elevated canopy temperatures induced by rootworm feeding were detected through infrared thermometry in commercial corn fields, however differences (P < 0.05) in canopy temperatures were noted only after 10 July. Although these data show that elevated canopy temperatures induced by rootworm feeding can be detected with infrared thermometry, some inconsistency in results was observed. Various reasons for why the technique was not more reliable are discussed.

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