Grains Research and Development

Date: 01.09.2002

Media debate - a little goes too far

THE MEDIA uproar over Bt maize, based on concern for the Monarch butterfly, provides a classic example of how a preliminary observation can be blown out of proportion and distort the environmental debate. In this case, the widespread publicity helped spur the European Union's move against GM crops. But what were the facts?

A letter in the journal Nature reported that when larvae of the Monarch butterfly were fed milkweed leaves covered with pollen from a GM maize variety with a Bt insectresistance gene, the Monarch larvae suffered ill-effects. Milkweed commonly grows next to cornfields in the USA and is an important food for the Monarch butterfly. The authors of the letter concluded that this observation warranted more study.

While the ecology of the Monarch butterfly was under the microscope, some parties rushed to publicise the initial observation as another proof of harm from GM crops.

Scientists looked at how much corn pollen Monarch larvae are likely to eat in the real world and also whether all types of Bt maize pollen were toxic to the larvae. The team concluded that Monarch butterfly larvae are unlikely to eat enough pollen to cause a problem. They also found that only one version of Bt maize produced toxic pollen and this version is no longer used.

The research clearly showed that habitat destruction and pesticide applications were the real worries for the butterfly.

Faulty experimental design?

The Life Sciences Network web site posted a critique by AgBioWorld saying the design of the initial Monarch butterfly experiment suffered from 'irrelevance bias'. This referred to the fact that the observation did not include a control such as feeding the Monarch larvae a diet of chemical insecticide - mimicking real life in the field.

On the same basis, AgBioWorid criticises recent work coming out of the University of Nebraska and Indiana University which claims that genetically modified crops can outcross to weedy relatives. The critique says that, in order to make judgements about environmental risk that were meaningful to the farming community, the experiment should have, but hadn't, compared the weed cross potential of trans genes to the weed cross potential of conventionally bred crops.


The Life Sciences Network (LSN) recently established in Australia after starting in New Zealand in the lead-up to the Royal Commission on Genetic Modification. It is an umbrella group of industry organisations, scientific institutions, universities and producer and grower organisations, and acts as an advocate in the public debate to ensure responsible genetic modification (GM) is an acceptable choice in Australia and New Zealand.

The LSN web site is a resource and information centre at:

AgBioWorld - - is an organisation of US science professionals devoted to bringing information about technological advances in agriculture to the developing world. Members believe recent developments in plant science, such as biotechnology, can and should be used to increase crop yields, grow more nutritious plants and reduce dependence on chemicals in order to alleviate hunger and to help preserve the environment.