There are inherent problems with inserting foreign genes into plants to protect them against insect attack. Insects quickly develop resistance and there is always a risk that a mutation could make the toxin dangerous to humans, according to an Irish specialist.
The study conducted by Dr Arpad Pusztai at the Rowett Research Institute in Aberdeen involved feeding lectin, a plant-produced natural poison against insects, to rats to assess toxicity.
There are also commercial plant products which use the Bt toxin gene to protect against insects. Bt toxin is a chemical produced by a gene taken from the bacterium, Bacillus thuringen.
"As a strategy there are problems with these," said Dr Michael Ryan, senior lecturer in the Department of Zoology at UCD.
"There is a lingering doubt over the toxin," he said, as well as questions about whether the gene will stay in the plants over generations. Insects also rapidly develop resistance. "This is just another toxin and every toxin ever used goes down to defeat because of resistance."
He has begun work on a new approach which involves identifying what attracts the insects to the plant in the first instance. Most insects locate food by responding to substances given off by the plant and Dr Ryan's work is about trying to block or reduce this natural chemical signal.
The approach is "entirely new" and is being assessed for its potential.
He first establishes the attractant for a given insect. Next he uses a "library" of 100 million different antibodies which occur naturally in a range of plant microorganisms in a process called "biopanning". This involves looking for antibodies which will attach to the chemical attractant and so damage or inhibit it.
The gene that produces the antibody is cloned so that the amount of antibody that can be produced by the micro-organism is increased. The micro-organism is then allowed to enter the plant as it would naturally.
The micro-organism begins to produce antibodies or "plantibodies" which interfere with the insect attractant, thus making the plant "invisible" to the bugs.
"The first advantage is you are not introducing a toxic molecule," so there are no questions over safety, Dr Ryan said. There is no permanent change to the plant's DNA, and the micro-organisms and antibodies they produce occur naturally.
It does not involve trying to kill off the insect, so resistance to the treatment does not arise. "You are essentially manipulating insect behaviour," he said, so it was much more difficult for the insect to adapt. "We won't be accelerating resistance."
The proving of the concept is only underway, but if successful it could greatly reduce dependence on chemical spraying.
Dr Ryan sees enormous potential for the technology in developing countries to protect against cereal aphids, rice hoppers and other insects which affect key food crops. In theory it should work on any crop, however, so long as the attractant is not used by both "good" and "bad" insects.