Friday, February 07, 2003

A new paper in PNAS shows that Bt cotton adoption in Arizona has significantly reduced the baseline population of pink bollworm. Unfortunately I am statistically illiterate, so I can't figure out exactly what "significant" is. Whether this is a good thing or not is another question -- since Bt cotton is so effective against the pest, it shouldn't matter much how many there are, while the population decline would seem to create particularly severe selection pressure. One the other hand, the smaller the population, the less "supplementary" pestcide to spray, and the more non-Bt refuge you can have, thus decreasing selection pressure.

But who knows what the unintended effects will be of the elimination of such pests from local ecosystems? Maybe nothing, maybe not.

I have to admit, I want some of this shit for my closet. Why can't we get Bt-impregnated cashmere? That would be a true benefit to mankind.

2/10: more from Science News:

Carri�re cautions that success depends on avoiding pesticide resistance. Lab work has shown that pink bollworms already carry gene variants that in certain combinations can provide immunity. Arizona scientists monitor yearly fluctuations in the prevalence of these variants in insects in the field but haven't observed resistant insects. Carri�re says, "So far, so good."
Meanwhile, Science reports that Bt cotton yields in Indian field trials were up over 80% -- the striking improvement is compared to fields that essentially used no pesticides before (because they are too expensive; in the "first world," where cotton is hosed down regularly, the difference is about 10%). Summary at SciDev.Net.

2/11:AP has dissonnant details:

But Nilakanti and pockets of other Indian cotton farmers who planted the biotech cotton seed complained that the pricey technology was a bad investment because their yields have not improved. The ruinous boll weevils have not disappeared.

Nilakanti paid about $33 for a 450-gram packet of BT seeds, nearly four times the cost of traditional seeds.

Standing in his field, Nilakanti watched boll weevils pop up their heads as if in a greeting and then resume their business of eating away his cotton crop.

"BT bedaappa," Nilakanti said in his native tongue, Kannada. "I do not want BT."


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