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In reply to the discussion: Insect Experts issue "Urgent" Warning on using GM seeds [View all]Tumbulu
(6,631 posts)but the differences that I refer to were written up in the old textbooks on B.t. (written during the 50's through the 80's). Lots of literature on the mode of action and specificity of the crystal and in the 80's when the B.t. toxins were first being engineered to be expressed by other bacteria the difference in biodegradability between the protoxin in a liquid vs the crystallin form. These would be in the old journals of insect biocontrol...do you think that they can be accessed online?
I personally ran the first greenhouse trials of the protoxin expressed as a liquid, not a crystal and it's action lasted 12-14 days vs 24 hr (which reflected the fact that the crystal broke down into non toxic to insect forms so rapidly).
This is why in 1986 at the Entomological Association meetings we had the scientists from the companies doing the genetic engineering promise us that they would not use the sequences from the B.t. strains that were being commercially produced as a crystal since anyone could see that a 10-12 day persistence of active ingredient vs a 24 hr in the environment spelled RESISTANCE pretty darn quickly. We argued that the normal B.t. was a biopesticide held by the commons and it's activity was not to be destroyed in this way.
The issue of changes in specificity were to be answered by an outside lab.
I remember the day of shock when the EPA ruled that this protoxin produced by engineering would be treated as the same as the crystal by them. No testing on mode of action, specificity, or why the biodegradability was so different- absolutely nothing. So, the engineers ended up being unable to keep their promises as the business people no way wanted a product in anyway different from the crystal because they did not want to have to run all these tests for the EPA......
The nightmare began.