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

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 sanforde@uidaho.edu 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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  1. Understanding resistance to cabbage seedpod weevil in yellow mustard xcanola hybrids Sanford Eigenbrode Plant, Soil and Entomological Sciences University of Idaho, Moscow, 83844-2339 sanforde@uidaho.edu Idaho Oilseed Conference 12 Feb 2009

  2. 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

  3. Long term goal – oilseed crops resistant to the CSPW

  4. Mustard • Condiment yellow mustard, Sinapis alba • High glucosinolate concentrations • Resistant or tolerant to most insects Sinapis alba A ‘non-host’ for CSPW

  5. Mustard Two approaches • Breed for oilseed quality mustard that retains resistance • Introduce resistance from yellow condiment mustard into B. napususing interspecific crossing

  6. Mustard Two approaches • Breed for oilseed quality mustard that retains resistance • Introduce resistance from yellow condiment mustard into B. napususing interspecific crossing

  7. 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

  8. Parental Species Glucosinolate Profiles (μmol/g)

  9. 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

  10. 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

  11. 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

  12. 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

  13. Canister Choice Tests After 1 day ofoviposition: dissect under a light microscope Count feeding punctures and eggs. Cabbage Seedpod Weevil Eggs

  14. 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)

  15. 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

  16. 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.

  17. 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.

  18. 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

  19. 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

  20. Questions ?

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