scholarly journals Evaluation of SmartStax and SmartStax PRO maize against western corn rootworm and northern corn rootworm: efficacy and resistance management

2017 ◽  
Vol 73 (9) ◽  
pp. 1883-1899 ◽  
Author(s):  
Graham P Head ◽  
Matthew W Carroll ◽  
Sean P Evans ◽  
Dwain M Rule ◽  
Alan R Willse ◽  
...  
Keyword(s):  
Resistance Management ◽  
Western Corn Rootworm ◽  
Corn Rootworm ◽  
Northern Corn Rootworm

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.

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 Genetic Markers for Western Corn Rootworm Resistance to Bt Toxin

2015 ◽  
Vol 5 (3) ◽  
pp. 399-405 ◽  
Author(s):  
Lex E Flagel ◽  
Shilpa Swarup ◽  
Mao Chen ◽  
Christopher Bauer ◽  
Humphrey Wanjugi ◽  
...  
Keyword(s):  
Genetic Markers ◽  
Insect Resistance ◽  
Management Strategies ◽  
Resistance Management ◽  
The United States ◽  
Western Corn Rootworm ◽  
Economic Losses ◽  
Corn Rootworm ◽  
Insect Resistance Management ◽  
Bt Toxin

Abstract Western corn rootworm (WCR) is a major maize (Zea mays L.) pest leading to annual economic losses of more than 1 billion dollars in the United States. Transgenic maize expressing insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt) are widely used for the management of WCR. However, cultivation of Bt-expressing maize places intense selection pressure on pest populations to evolve resistance. Instances of resistance to Bt toxins have been reported in WCR. Developing genetic markers for resistance will help in characterizing the extent of existing issues, predicting where future field failures may occur, improving insect resistance management strategies, and in designing and sustainably implementing forthcoming WCR control products. Here, we discover and validate genetic markers in WCR that are associated with resistance to the Cry3Bb1 Bt toxin. A field-derived WCR population known to be resistant to the Cry3Bb1 Bt toxin was used to generate a genetic map and to identify a genomic region associated with Cry3Bb1 resistance. Our results indicate that resistance is inherited in a nearly recessive manner and associated with a single autosomal linkage group. Markers tightly linked with resistance were validated using WCR populations collected from Cry3Bb1 maize fields showing significant WCR damage from across the US Corn Belt. Two markers were found to be correlated with both diet (R2 = 0.14) and plant (R2 = 0.23) bioassays for resistance. These results will assist in assessing resistance risk for different WCR populations, and can be used to improve insect resistance management strategies.

EFFECT OF SOIL APPLICATIONS OF CARBOFURAN ON EGG POPULATIONS OF THE NORTHERN CORN ROOTWORM (COLEOPTERA: CHRYSOMELIDAE)

1981 ◽  
Vol 113 (1) ◽  
pp. 73-73
Author(s):  
B. C. Smith
Keyword(s):  
Clay Soil ◽  
Economic Importance ◽  
Western Corn Rootworm ◽  
Corn Rootworm ◽  
Laboratory Studies ◽  
Sublethal Doses ◽  
Northern Corn Rootworm ◽  
Topical Applications

Control of nothern corn rootworm, Diabrotica longicornis (Say), resulting from soil applications of carbofuran in southwestern Ontario varied considerably (Smith 1980). However, Ball and Su (1979) showed in laboratory studies that topical applications with sublethal doses of carbofuran increased the longevity and fecundity of western corn rootworm, D. virgifera LeConte, females. This is a report of effects of soil applications of carbofuran on northern rootworm egg populations in corn grown without rotation. The work was done in conjunction, with studies to determine the economic importance of larval populations on clay soil at two locations in southwestern Ontario. Details of methods of applying carbofuran and sampling rootworm eggs were described (Smith 1980).

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