FARMERS may need to douse their fields with yet more pesticides to get the
best out of genetically modified plants. At least, that鈥檚 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. 鈥淏t toxin has a rather narrow spectrum of activity, so you
don鈥檛 get control of all pests,鈥� says Walter Smolders, head of patents at
Novartis Seeds.
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To find a way round the problem, Novartis scientists tried applying different
combinations of the company鈥檚 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鈥檚 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. 鈥淣on-target species don鈥檛 suck the plants, so they鈥檙e not
harmed,鈥� 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鈥檚 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鈥檚
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. 鈥淚t鈥檚 the impact of the whole process on
biodiversity that counts,鈥� he says. 鈥淏ut the impacts of what they are proposing
are not known.鈥�