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Understanding resistance to cabbage seedpod weevil in yellow mustard x canola hybrids PowerPoint PPT Presentation


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Understanding resistance to cabbage seedpod weevil in yellow mustard x canola hybrids. Sanford Eigenbrode Plant , Soil and Entomological Sciences University of Idaho, Moscow, 83844- 2339 [email protected] Idaho Oilseed Conference 12 Feb 2009. Insect pests in canola.

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Understanding resistance to cabbage seedpod weevil in yellow mustard x canola hybrids

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Understanding resistance to cabbage seedpod weevil in yellow mustard xcanola hybrids

Sanford Eigenbrode

Plant, Soil and Entomological Sciences

University of Idaho, Moscow, 83844-2339

[email protected]

Idaho Oilseed Conference

12 Feb 2009


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Insect pests in canola

  • 10% - 40% yield reductions from all insects.

  • One persistent insect problem is the cabbage seed pod weevil (CSPW)

  • A crucifer specialist

  • Can reduce rapeseed yields up to 35% (McCaffrey et al., 1986)

Ceutorhynchusobstrictus

CSPW


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Long term goal – oilseed crops resistant to the CSPW


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Mustard

  • Condiment yellow mustard, Sinapis alba

  • High glucosinolate concentrations

  • Resistant or tolerant to most insects

Sinapis alba

A ‘non-host’ for CSPW


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Mustard

Two approaches

  • Breed for oilseed quality mustard that retains resistance

  • Introduce resistance from yellow condiment mustard into B. napususing interspecific crossing


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Mustard

Two approaches

  • Breed for oilseed quality mustard that retains resistance

  • Introduce resistance from yellow condiment mustard into B. napususing interspecific crossing


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Canola x yellow mustardhybrids

cross-pollination between S. alba and B. napus followed by a combination of ovule culture and embryo rescue (Brown et al., 1997)

X


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Parental Species

Glucosinolate Profiles (μmol/g)


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Hybrid Glucosinolate Profile

R = ‘Resistant’ to CSPW

= eggs 17% to 25% of control

S

R

R

R

S = ‘Susceptible’ to CSPW

= eggs 40 to 70% of control

µmol/g

S

Ross et al. 2003

R

S


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Conclusions from prior work

  • Resistance varies widely in S. alba x B. napus hybrids

  • The best lines tested so far are not as resistant as the resistant parent, S. alba

  • The mechanism is unknown, but appears to be unrelated to glucosinolate profiles


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Objectives of this project

  • Screen additional interspecific hybrids, seeking additional hybrids resistant to oviposition by CSPW

  • Having identified resistant hybrids

    • Employ detailed behavioral bioassay to ascertain weevil responses

    • Conduct a wider survey of metabolites potentially responsible for resistance

    • Characterize pod morphology


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Screen: Canister Choice Tests

  • 25 entries:

    • 5 parents + 20 hybrids

  • choice test:

    • each entry against Cyclone

    • excised ripe pods placed in cages with 1 ovipositing female weevil.

    • Count punctures, oviposition holes, eggs deposited (by dissection)

    • N = 10

Canisters for insect choice tests


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Canister Choice Tests

After 1 day ofoviposition:

dissect under a light microscope

Count feeding punctures and eggs.

Cabbage Seedpod Weevil Eggs


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Observations

  • Selected lines, based on resistance and phenotype will be tested in no-choice setting

  • Individual ovipositing female weevils will be observed continuously for 1 hour

  • Behavior on susceptible and resistant types compared for number of events and time spent engaged in:

    • Pod exploration

    • Preliminary feeding

    • Egg cavity formation

    • Turning

    • Ovipositing

    • Retracting

    • Pod brushing

      Following Kozlowski et al. (1983)


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Observations

  • Resistant and susceptible reactions will be compared statistically

  • Noldus ‘Observer’ behavioral software

  • Key behaviors correlated with different types of resistance will be noted

  • N = 40 individual weevils x 8 selected lines


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Characterization

  • Measure pod size, toughness, hairiness and correlate these features with observed resistance.

  • Conduct a broad metabolic screen of the most resistant pod tissues to identify chemical profiles other than glucosinolates that could confer resistance.


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Chemical characterization

  • Ongoing project on host relationships of Ceutorhynchuscardaria(hoary cress biological control)

  • Employs metabolic profiling (≈ 200 metabolites included).

  • Samples of most promising S. alba x B. napus hybrids can be included.


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Years 1 and 2

  • Year 1

    • bioassay, focus on the initial screening using choice tests (using live collected weevils)

    • characterize pod material morphologically and chemically (winter)

  • Year 2

    • bioassay, focus on direct observational studies (live collected weevils)

    • Select lines for additional development


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  • Special notes

  • Project initiated by Joe McCaffrey (UI Entomology)

  • Long experience and expertise includes CSPW and other pests of oilseed Brassicacrops

  • My credentials for this project

  • M.S. and Ph.D. on aspects of Brassica entomology

  • Background in Host Plant Resistance to insects

  • Expertise in chemical ecology, plant defenses, glucosinolates

  • Veteran collaborator with Jack Brown


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Questions ?


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