scholarly journals Initial Screening of Sweet Corn Tissues for Allelochemicals that Affect European Corn Borer Larval Development

HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 622c-622
Author(s):  
Daniel F. Warnock ◽  
David W. Davis ◽  
William D. Hutchison
Keyword(s):  
European Corn Borer ◽  
Field Experiments ◽  
Chemical Resistance ◽  
Sweet Corn ◽  
Resistance Breeding ◽  
Developmental Time ◽  
Larval Weight ◽  
Corn Borer ◽  
Resistance Factors ◽  
Breeding Efficiency

European corn borer (ECB), Ostrinia nubilalis Hübner, can severely affect sweet corn quality. Selection techniques in field experiments have improved ear feeding resistance associated with morphological features and/or allelochemicals. A laboratory bioassay was used to detect chemical resistance factors in silk and kernel tissues of 10 variously resistant sweet corn genotypes. When added to a nutritively complete diet, kernel tissue from W182E, MN275, and MN272 decreased (P ≤ 0.05) 10-day larval weight (66.3, 61.7, and 54.5 mg, respectively) while kernel tissue from MG15, MN270, and MN3053 increased (P ≤ 0.05) 10-day larval weight (88.3, 81.5, and 80.8 mg, respectively) compared to a cellulose control (71.0 mg). These weight differences, however, were not significant developmentally as 10-day larval maturation (fourth to fifth instar) and pupation time (13.9 to 16.3 days) were similar to the cellulose control (fifth instar and 14.8 days). Silk tissue additions to the diet decreased (P ≤ 0.05) 10-day larval weight compared to the cellulose control (71.0 mg). Larvae exposed to diet containing silk tissue from MN3053, W182E, and `Apache' were lightest (9.1, 8.3, and 7.8 mg, respectively). The heaviest larvae exposed to silk tissue were from diet including `Jubilee' tissue (54.1 mg). Contrary to the instar levels found on the cellulose control, larvae feeding for 10 days on a diet containing silk tissue mainly were at third or early fourth instar excluding larvae exposed to `Jubilee' silk (fourth to fifth instar). For all genotypes, silk additions to diet increased the pupation time compared to kernel additions. Kernel, and especially silk tissue, may contain chemical resistance factors which decrease larval weight and increase developmental time. Identifying sweet corn genotypes with chemical resistance factors may enhance ECB resistance breeding efficiency.

scholarly journals Developing Methodology for Evaluating Sweet Corn Tissues for Allelochemicals Restricting European Corn Borer Larval Development

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 543E-544
Author(s):  
Daniel F. Warnock ◽  
David W. Davis ◽  
William D. Hutchison
Keyword(s):  
Larval Development ◽  
Growth And Development ◽  
European Corn Borer ◽  
Field Experiments ◽  
Sweet Corn ◽  
Larval Growth ◽  
Larval Weight ◽  
Isolation And Identification ◽  
Corn Borer ◽  
The Status

European corn borer, Ostrinia nubilalis Hübner, can severely affect sweet corn quality. Selection techniques in field experiments have improved ear feeding resistance associated with morphological features and/or allelochemicals. The isolation and identification of allelochemicals that detrimentally affect O. nubilalismay improve breeder selection for host plant resistance, thus reducing the need for insecticide application. A laboratory bioassay was used to detect chemical resistance factors in silk and kernel tissues of 10 variously resistant sweet corn genotypes. Ground lyophilized tissue from field-grown plants was added to a nutritionally complete larval diet before infestation with O. nubilalis neonates. Larval weights on a 10-day basis and time to pupation were recorded to estimate larval development. Tissue and genotype main effects affected (P ≤ 0.05) 10-day larval weight and time to pupation. Silk tissue (P ≤ 0.05) reduced 10-day larval weight and increased the time to pupation compared with kernel tissue and the cellulose control, which did not differ. Silk tissue reduced larval weight by 65% and increased time to pupation by 4.0 days compared with the cellulose control. Genotypes variously affected (P ≤ 0.05) larval growth and development, reducing 10-day larval weight up to 51% and increasing the time to pupation up to 4.2 days when comparing the best genotype for each developmental stage with the cellulose control. Silk tissue of some genotypes may contain allelochemicals that decrease the rate of larval growth and development. The status of allelochemical detection in silk tissue will be discussed.

Labortory Bioassays for Evaluating Sweet Corn Antibiosis on European Corn Borer (Lepidoptera: Pyralidae) Larval Development

1997 ◽  
Vol 32 (3) ◽  
pp. 342-357 ◽  
Author(s):  
Daniel F. Warnock ◽  
William D. Hutchison ◽  
Timothy J. Kurtti ◽  
David W. Davis
Keyword(s):  
Larval Development ◽  
European Corn Borer ◽  
Sweet Corn ◽  
Weight Basis ◽  
Equal Weight ◽  
Plant Tolerance ◽  
Larval Weight ◽  
Isolation And Identification ◽  
Corn Borer ◽  
Contaminant Control

European corn borer (Ostrinia nubilalis Hübner) can severely affect commercial sweet corn quality during years of heavy infestation. The isolation and identification of allelochemicals in sweet corn which detrimentally affect O. nubilalis may enhance breeder selection for greater ear feeding resistance, thus reducing the need for insecticide application. Field selection techniques for improving plant resistance to O. nubilalis cannot easily distinguish between plant tolerance or antibiosis. A laboratory bioassay incorporating ear tissues from field resistant and susceptible sweet corn genotypes into a nutritionally complete O. nubilalis larval diet was developed as an initial step to facilitate the isolation and identification of potential chemical resistance factors in sweet corn. Neonates reared for 7 d on a meridic diet with limited fungal and bacterial contaminant control agents weighed more than larvae grown on a comparable diet with high levels of contaminant control (5.96 and 2.46 mg, respectively). Silk tissue from several sweet corn genotypes significantly reduced larval weight and increased total larval development time compared with kernel tissue. Silk tissues incorporated on a weight basis had volumes about 3 × that of an equal weight of kernel tissues. However, tissues incorporated into a specific diet volume on a weight or volume basis usually did not alter larval weight or time to pupation within a genotype. Incorporation on a weight basis was most time efficient. Future bioassays screening for antibiotic effects of sweet corn tissue on O. nubilalis development should utilize a diet with limited contaminant control agents, incorporate tissue on a weight basis, and focus on silk tissue.

scholarly journals Evaluation of Two Visual Scales to Estimate European Corn Borer Ear Feeding Damage in Sweet Corn

HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 613a-613
Author(s):  
Daniel F. Warnock ◽  
David W. Davis
Keyword(s):  
European Corn Borer ◽  
Sweet Corn ◽  
Resistance Breeding ◽  
Breeding Program ◽  
Economic Consequences ◽  
Economic Damage ◽  
Feeding Damage ◽  
Corn Borer ◽  
Damage Site ◽  
Moderately Resistant

The germplasm evaluation techniques in resistance breeding programs may improperly characterize insect damage. For example, the relationship between economic damage levels and biological damage levels may not be linear as some techniques assume. Most commercial sweet corn hybrids are highly susceptible to European corn borer (ECB), Ostrinia nubilalis Hübner, ear feeding. Genotype variation for ECB damage in our breeding program traditionally has been identified by using a 1 (no damage) to 9 visual rating scale that combines damage levels, damage site on the ear, and the economic consequences of ECB feeding for the processing industry. An alternative 1 to 5 scale based solely on a visual percentage assessment of ear feeding damage was developed and compared to the traditional scale. Seven entries, including moderately resistant and susceptible hybrids and inbred lines of the ECB ear resistance breeding program, were evaluated with both scales in 1994 and 1995 at two locations. Inbred MN3002, Hybrid MN3004, `Apache', and `More' had lower mean damage ratings (3.4, 3.4, 3.6, 3.8, traditional vs. 2.4, 2.2, 2.2, 2.3, alternative, respectively) than `Jubilee', Inbred W182E, and Inbred MN3003 (5.3, 5.6, 7.3, traditional vs. 3.3, 3.0, 4.2, alternative, respectively). Thus, four entries were classified as moderately resistant (3.0 to 4.0 traditional vs. 2.0 to 3.0 alternative) and three entries were classified as susceptible (>4.0 traditional vs. >3.0 alternative). Individual entry ranks varied by scale, but this did not alter resistance classifications. Although the nine traditional ratings were based on economic consequences and the five alternative ratings were based strictly on feeding levels excluding damage location, both scales effectively identified genotypes historically classified as moderately resistant and susceptible. The value of scales is often questionable for many situations and should be considered prior to evaluation.

scholarly journals Inheritance of Ear Resistance to European Corn Borer in Sweet Corn

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 450D-450
Author(s):  
Daniel F. Warnock ◽  
David W. Davis
Keyword(s):  
Combining Ability ◽  
European Corn Borer ◽  
Field Experiments ◽  
Rating Scale ◽  
Sweet Corn ◽  
Channel Length ◽  
Feeding Damage ◽  
Corn Borer ◽  
Wide Range ◽  
Feeding Resistance

European corn borer, Ostrinia nubilalis Hübner, is an economic pest of sweet corn. Consumer demand for high-quality, insect-free produce with minimal pesticide residue necessitates exploitation of various control options. Ear feeding resistance could reduce insecticide inputs. The inheritance of ear feeding resistance and silk channel length in the F1 derived from a diallel cross (Griffing's model I, method 2) of eight breeding stocks describing a wide range of feeding resistance was investigated in field experiments. Feeding damage, based on a 1 (no damage) to 9 (>10% ear damage) visual rating scale, and silk channel length of ears that had been manually infested at the ear tip with O. nubilalis were recorded. A significant (P ≤ 0.05) year by location interaction was found for ear feeding damage and silk channel length. Genotype ear feeding damage and silk channel length differences were significant (P ≤ 0.01) beyond genotype by environment (year and location) interactions. Mean feeding damage ranged from 2.5 (parents 1 × 7) to 8.8 (parent 2) and mean silk channel length ranged from 1.9 cm (parents 2 × 7) to 9.0 cm (parent 3). Ten of the 28 possible crosses (reciprocals combined) and 1 parent were classed as resistant (damage rating < 3.0). Eleven crosses, including all 7 involving parent 2, and 2 parents were susceptible (damage rating > 4.0). Pearson's correlation analysis indicated lower damage levels were weakly to moderately associated with increased silk channel length for both parents (r = –0.18) and progeny (r = –0.44). The general combining ability (GCA) component was significant (P ≤ 0.01) for ear feeding damage, suggesting additive effects control ear feeding damage. GCA and specific combining ability (SCA) effects did not account for silk channel length variability, suggesting strong environmental influences. Improved ear feeding resistance should be possible via recurrent selection with recombination.

scholarly journals CONTROL OF CORN EARWORM AND EUROPEAN CORN BORER ON SWEET CORN, 1998

1999 ◽  
Vol 24 (1) ◽  
Author(s):  
P. K. O'Rourke ◽  
E. C. Burkness ◽  
W. D. Hutchison
Keyword(s):  
European Corn Borer ◽  
Sweet Corn ◽  
Corn Earworm ◽  
Corn Borer
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