Unintended Consequences Using RNAi Pesticides?

(The following is brought to us by CATCH THE BUZZ (Kim Flottum) Bee Culture, The Magazine of American Beekeeping, published by A.I. Root Company.) 

By Alan Harman

A new technology for creating pesticides and pest-resistant crops could damage beneficial species that present toxicity testing will miss, U.S. Agricultural Research Service scientists are warning.

Jonathan G. Lundgren and Jian J. Duan say standard toxicity testing is inadequate to assess the safety of the new technology, which has the potential for creating pesticides and genetically modifying crops.

In a report in the journal BioScience, Lundgren and Duan argue that pesticides and insect-resistant crops based on RNA interference, now in exploratory development, may have to be tested under elaborate procedures that assess effects on animals' whole life cycles, rather than by methods that simply look for short-term toxicity.

RNA interference is a natural process that affects the level of activity of genes in animals and plants.

Agricultural scientists have successfully devised artificial “interfering RNAs” that target genes in insect pests, slowing their growth or killing them. The hope is that interfering RNAs might be applied to crops, or that crops might be genetically engineered to make interfering RNAs harmful to their pests, thus increasing crop yields.

The safety concern is that the artificial interfering RNAs will also harm desirable insects or other animals. And the researchers say the way interfering RNA works means that simply testing for lethality might not detect important damaging effects.

An interfering RNA, for instance, might have the unintended effect of suppressing the action of a gene needed for reproduction in a beneficial species. Standard laboratory testing would detect no harm, but there could be ecological disruption in fields because of the effects on reproduction.

Lundgren and Duan suggest that researchers investigating the potential of interference RNA pesticides create types that are designed to be unlikely to affect non-target species as well as a research program to evaluate how the chemicals act in real-life situations.

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