DW:
Dr. Christoph Then used to work for Greenpeace, and now works for Testbiotech - a non-profit organization that casts a critical eye on GM technology and its possible effects on humans and the environment.

Now how would you actually judge it? What's better - genetic engineering or the massive use of insecticides?

Christoph Then:
Both are a problem. I would not give a priority to one or another. There are massive problems with olive flies, especially under certain climate conditions, like this year. We have massive attacks of olive flies and we do not have a patent solution to this problem.

With genetically engineered olive flies, you face the problem that you cannot keep them under control. They will fly across borders, they'll go to the organic farms, and you can never remove them from the environment if something goes wrong. This kind of long-term exposure to the environment and long-term risk is not the case with insecticides. There are other risks with insecticides.

Of course, there are ecological risks. The consequences for the ecology are pretty disastrous. So if you had to judge it, you would say at this time, right now, that we would rather use insecticides?

I would rather see a concept like that of the organic farmers. They have traps for olive flies, and try to collect the flies by drawing them away from the olives. They then collect the dead olive flies in the olive garden. Of course, with the massive growing populations like this year's, and under specific climate conditions, this might not work for one year - and then you have to wait for a better environment, and next year it could also be an economic difficulty for the organic farmers.

In a way it's a similar approach, because both times we try to make the olive fly disappear from the ecosystem. Would it be disastrous for the ecosystem if there were no olive flies anymore?

We have to work with biodiversity and not try to make a certain species extinct. If the Oxitec concept is right, this means the olive fly will disappear completely. As long as the genetically engineered olive flies mate with the native population, in the end the concept is extinction. And I don't think we have the right ethically to extinguish a whole species just for economic reasons. On the other hand, this will have huge consequences for the ecosystems.

We have lots of experience with genetically modified organisms in the field of plants. Large parts of the world's corn and soy plants have been genetically modified, but we haven't seen those dramatic consequences for the ecology.

The basic difference in the concept is that the genetically modified plants are not supposed to leave the fields and are supposed to be harvested after one year. So this is under much more control than the olive fly, which is supposed to go into the environment to mate with native populations. It's completely different.

So we have to be careful there. Thanks a lot for the talk, Dr. Christoph Then.

(Interview: Ingolf Baur)