Category: Threats

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It’s a wise grape that knows its own father

In the annals of plant breeding there are many stories that have achieved the status of Truth. Like the discovery of the original pink grapefruit, the parent tree marked forever with a P carved in its trunk, or the Red Delicious apple found in a ditch somewhere. Not quite so well known is the tale of Cardinal grapes. It is a delicious table grape that, so the story goes, was bred in 1939 at the Horticultural Field Station in Fresno, California, by E. Snyder and F. Harmon, by crossing Flame Tokay and Ribier.

Alas, it ain’t so.

Flame Tokay is normally considered a synonym — just another name — for Ahmer Bou Amer, an Algerian table grape. In the course of examining the DNA of a bunch of Mediterranean grape varieties, A. Akkak, P. Bocacci and R. Rotta ((Cardinal grape parentage: a case of a breeding mistake. Genome 50(3): 325-328 (2007) doi:10.1139/G06-145)) discovered that Flame Tokay could not possibly have been a parent of Cardinal, though they cannot show who is either. I don’t imagine E. Snyder or F. Harmon is still around to tell us what really happened. The researchers also prove that Flame Tokay is not merely a synonym of Ahmer Bou Amer but a mutant in at least one gene.

And in other grape news, two scientists in Switzerland are warning that the American Vitis rootstocks that saved the European wine industry from Phylloxera are threatening the survival of native wild European grapevines. ((Arrigo N, Arnold C (2007) Naturalised Vitis Rootstocks in Europe and Consequences to Native Wild Grapevine. PLoS ONE 2(6): e521. doi:10.1371/journal.pone.0000521)) Nils Arrigo and Claire Arnold say that:

The regrouping of naturalised rootstocks in interconnected populations tends to create active hybrid swarms of rootstocks. The rootstocks show characters of invasive plants. The spread of naturalised rootstocks in the environment, the acceleration of the decline of the European wild grapevine, and the propagation of genes of viticultural interest in natural populations are potential consequences that should be kept in mind when undertaking appropriate management measures.

In other words, watch out.

The American rootstocks have already displaced wild grapes from the flood plains of the Rhone, and there may be worse in store.

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Pest and disease watch

California is synonymous with fruits and vegetables. An omnivorous pest would be a terrible thing. Cue the light brown apple moth, Epiphyas postvittana. LBAM, as we’re being familiar, would be better known as LBEM, the light brown everything moth, according to one expert quoted in the New York Times, because its larvae munch on just about anything green, including the grape vines of Napa county where it has just been found in large numbers. Omnivory suggests that diversity is unlikely to be much protection.

Then there’s potato wart ((I far prefer the alternative name Black Scab, but that’s probably just me.)), caused by the fungus Synchytrium endobioticum. It is so long-lasting in the soil that even though the direct economic losses are small, it causes enormous indirect losses as farmers are prevented from growing potatoes, according to a (long and thorough) story from the American Phytopathological Society. It’s even on the Federal Bioterrorism list for agricultural plant pathogens. Diversity might help there, if resistance can be found.

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The best bee paper ever … for now

What’s Killing American Honey Bees? by Benjamin P. Oldroyd, an Australian entomologist, is without a doubt the best summary of the current state of play on Colony Collapse Disorder. I know I’m biased, being — gasp — a scientist, but Oldroyd’s paper is the bees’ knees. It has hypotheses (wot, no mobile phones?), facts, and interpretations. And one rather interesting conclusion. I’ll let Oldroyd explain:

Remarkably, honey bees maintain the temperature of their brood nest within ± 0.5 °C of 34.5 °C, despite major fluctuations in ambient temperature. If the brood is incubated a little outside this range, the resulting adults are normal physically, but show deficiencies in learning and memory. Workers reared at suboptimal temperatures tend to get lost in the field, and can’t perform communication dances effectively. Although entirely a hypothesis, I suspect that if colonies were unable to maintain optimal brood nest temperatures, CCD-like symptoms would be apparent.

… snip …

I suggest that another possible cause of CCD might simply be inadequate incubation of the brood. Thus any factor—infections, chronic exposure to insecticides, inadequate nutrition, migration in adult population, and inadequate regulation of brood temperature might cause CCD-like symptoms.

My hypothesis could be easily tested by removing brood from several colonies and incubating some of it at optimal temperature and some at suboptimal temperature. The brood would then be used to constitute new colonies in which some colonies comprise workers raised at low temperature and some comprise workers raised at optimal temperature. I predict that the colonies comprising workers reared at suboptimal temperature will show signs of CCD. Moreover, I would not be surprised if they showed higher levels of stress-related viral infections. These effects could act synergistically—more virus leads to shorter-lived, less efficient workers, that in turn leads to suboptimal temperature regulation, and more short-lived bees.

See, kids, that’s the way science is done. But really, go read the article. And if there’s anything in it you honestly don’t follow, ask.