GENTECH archive


Spraying Bt Corn

>         NEWS 18/12/99
>         This week's stories
>         from New Scientist
>         available online.
>                                  Keep that spray
>                                  Crops made resistant to pests still do
> better with chemicals
>                                  FARMERS may need to douse their fields
> with yet more pesticides to
>                                  get the best out of genetically modified
> plants. At least, that's the
>                                  implication of patent applications filed
> by Novartis of Basle in Switzerland,
>                                  one of the leading companies in the field.
>                                  The applications (WO 99/35910 and WO
> 99/35913) were filed after
>                                  scientists at Novartis realised that a
> wide spectrum of insect pests was
>                                  attacking Bt maize, its major GM crop.
> Genes inserted into the maize
>                                  enable it to make the Bt toxin, a
> bacterial protein that kills European corn
>                                  borer larvae. These larvae chew their way
> into the stems of young maize
>                                  plants and can kill them before they get
> established.
>                                  But many GM plants that saw off the borer
> larvae were later attacked by
>                                  sap-sucking insects. "Bt toxin has a
> rather narrow spectrum of activity, so
>                                  you don't get control of all pests," says
> Walter Smolders, head of patents
>                                  at Novartis Seeds.
>                                  To find a way round the problem, Novartis
> scientists tried applying
>                                  different combinations of the company's
> pesticides to the Bt maize. Their
>                                  patents identify combinations of
> pesticides that could raise yields of the
>                                  maize by 20 per cent.
>                                  The same pesticides appear to increase the
> yields of other GM plants,
>                                  including those engineered to resist the
> effects of herbicides. So
>                                  Novartis has extended its patents to cover
> use of the pesticides on a
>                                  long list of transgenic crops including
> maize, cereals, soya beans,
>                                  potatoes, rice, cotton and mustard. If the
> patents are granted, this means
>                                  they will also apply to crops from
> competitors such as Monsanto of St
>                                  Louis, Missouri.
>                                  Heinz Hammann, head of patents in
> Novartis's crop protection division,
>                                  claims the pesticides mentioned in the
> patents are mostly
>                                  environmentally benign, killing only the
> pests which attack the plants.
>                                  Maize, for example, is vulnerable to
> sapsuckers such as the flea beetle
>                                  (Phyllotreta agriotes) and various aphids.
> "Non-target species don't
>                                  suck the plants, so they're not harmed,"
> he says.
>                                  But some of the pesticides are less
> friendly. Carbamates, for example, act
>                                  on the nervous system of pests and are
> known to affect birds, fish, game,
>                                  bees, mammals and other farmland wildlife.
> And given that agribiotech
>                                  firms have consistently argued that GM
> crops will reduce pesticide use,
>                                  Novartis's patent applications are sure to
> be seized upon by groups that
>                                  oppose the technology.
>                                  Brian Johnson, head of the biotechnology
> advisory unit at English
>                                  Nature, a conservation watchdog, says he
> wants to see evidence
>                                  confirming Novartis's suggestion that the
> use of pesticides on GM crops
>                                  outlined in its patent applications will
> be less environmentally damaging
>                                  than conventional chemical treatment of
> ordinary maize. "It's the impact of
>                                  the whole process on biodiversity that
> counts," he says. "But the impacts
>                                  of what they are proposing are not known.."
>                                  Andy Coghlan and Barry Fox
>                                              From New Scientist, 18
> December 1999
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