Breeding for pea weevil resistance

[William S.]

I have problematic pea weevils. Thanks to Andrew I have quite a bit of pea diversity, but I don't know for sure if any resistance is evident. Timing does seem to matter a bit. I'd be a good test site for resistant material.

[Andrew Barney]

I Like the jar test idea,  but I do think one should not ignore the pods. Perhaps if one could find resistant seed AND resistant or deterrent pods that would be the ideal combination.

I suspect the resistant ones might be more shelling, soup, or field peas with lots of tannins. Snow and snap might be out of the question.

[Andrew Barney]

Andrew: In some sense, I breed for pea weevil resistance every time I plant peas. Because those that are most susceptible are the least likely to produce viable seed.

Haha,  true,  but I thought you hadn't been planting them at all as of late.

Let me know if you want more random germplasm to try. I have jars of what I have labeled as "unknowns", which are mostly probably unknown hybrids and crosses. Very diverse.

I also have unusual seed colors like deep black seeds, purple seeds,  and more red seeds (bred from biskopens). Who knows,  maybe the black seeds are from p. fulvum and may have traits that resist bugs.

[Andrew Barney]

https://dl.sciencesocieties.org/publications/cs/abstracts/42/6/2167?access=0&view=pdf

The pea weevil, Bruchus pisorum (L.) (Coleoptera: Bruchidae), is one of the most intractable pest problems of cultivated pea, Pisum sativum L. The availability of resistant cultivars would give growers more pest management options. Searches for plant resistance to pea weevil were expanded to the Pisum secondary gene pool (P fulvum Sm.) because seed resistance had not been located in P sativum and subspecies. The objectives of this study were to determine the extent of pod and seed resistance to pea weevil in P fulvum, and to use the life table format to characterize weevil stage-specific mortality and survivorship on different P fulvum accessions. Mortality of first instar larvae on pods, mortality of all weevil stages within seed, adult emergence from seed, and seed damage levels were quantified. In two greenhouse trials, more larvae died (14 to 50% averages) on pods of P fulvum accessions than on pods of ‘Alaska 81’ (6% average), and mortality of first instar larvae entering seed of P fulvum accessions averaged 83.7%. Seed damage ratings (1 = feeding scar on seed testa, 0-1% cotyledon tissue eaten, dead first instar larva; 5 = extensive damage, live adult) averaged <3.0 for 26 P fulvum accessions, compared with mean ratings of 4.9 for Alaska 81. Using weevil mortality and survivorship values in life tables and adult emergence rates, entries were classified as susceptible (two controls and five accessions), moderately resistant (14 accessions), and resistant (12 accessions). Antibiosis resistance was based on the death of weevil larvae on pods and seed testa and cotyledon tissues. The results identify sources of natural weevil resistance in the Pisum genome (26 moderately resistant and resistant accessions of P fulvum) to endow pea cultivars with pod and/or seed resistance to B pisorum

[Lauren]

To select for seed based resistance, it would be easy to put a bunch of seeds on a jar and let the weevils do their thing over the winter.  (Hard to watch, but effective!). Freeze in the Spring (rather than early in the Fall) and plant the debris.  Of course, you need to make sure the weevils don't escape!

I did this a few years, in a sense. I put the peas in a closed jar after they were dried out. The weevil that hatched headed for the top of the jar, presumably to be closer to any oxygen. I sorted out the peas that had holes and planted the rest.

I do it differently now. I sort for those with holes and then fumigate the seeds. If I was breeding for this I'd divide the seeds by plant and plant those that had the fewest weevil.

[PhilaGardener]

I did this a few years, in a sense. I put the peas in a closed jar after they were dried out. The weevil that hatched headed for the top of the jar, presumably to be closer to any oxygen. I sorted out the peas that had holes and planted the rest.

I do it differently now. I sort for those with holes and then fumigate the seeds. If I was breeding for this I'd divide the seeds by plant and plant those that had the fewest weevil.

Nifty to hear someone has tried this!  After several years, any impact on the extent of infestation?

[Lauren]

Last year I found no pea weevils among those I kept for seed, but can't prove causation. It wasn't deliberate.