Biotech’s Idolized Bt Technology May Transform Benign Insects Into Pests
by Sayer Ji
A new study reveals that one of the most widely used GM pest control technologies could actually be increasing pest virulence in non-target and normally benign species.
A new study published in the biological sciences journal of the Proceedings of the Royal Society reveals a profound flaw in one of the most widely used genetic engineering technologies within Biotech’s pest control arsenal, namely, Bt technology, wherein crops of commercial importance are made to express insecticidal Cry proteins derived from Bacillus thuringiensis (Bt).
The new study titled, “Pest trade-offs in technology: reduced damage by caterpillars in Bt cotton benefits aphids,” addresses increasing concern about how Bt technology might adversely affect non-target insects, and by virtue of this, the fitness of the Bt plants themselves. Whereas much of the focus in the past has been on the possibility that Bt could harm and/or disrupt pollinator species, this new review addresses the equally concerning potential of Bt technology to enhance predatory behavior in non-target, normally benign insect species.
According to the researchers:
Although studies have now reported increased populations of non-target herbivores in Bt cotton, the underlying mechanisms are not fully understood. We propose that lack of herbivore-induced secondary metabolites in Bt cotton represents a mechanism that benefits non-target herbivores. We show that, because of effective suppression of Bt-sensitive lepidopteran herbivores, Bt cotton contains reduced levels of induced terpenoids. We also show that changes in the overall level of these defensive secondary metabolites are associated with improved performance of a Bt-insensitive herbivore, the cotton aphid, under glasshouse conditions.
Essentially, Biotech’s primary justification for incorporating Bt transgenes into their ‘improved’ GM plants, would be disproved by the discovery that natural predatory challenges actually help non-GM plants fend off attack against non-target herbivore insects such as aphids through the production of defensive chemistries, e.g. “induced terpenoids.” Whereas it was believed that ‘weaponizing’ corn and soy plants with the capability to produce large amounts of Bt Cry proteins would ‘make the plant’s biochemical arsenal stronger against insect attack,’ it is may actually be making them weaker by removing certain aspects of their natural immunity.
Ultimately, if one of the unintended, adverse consequences of Bt technology is the down-regulation of a plant’s natural immunity and the subsequent transformation of relatively non- or less-predatory insects into more predatory ones, the Biotech promise of a reduced requirement for agrichemicals, specifically insecticides, in the production of GM crops, would be found to be patently false.
 Steffen Hagenbucher, Felix L Wäckers, Felix E Wettstein, Dawn M Olson, John R Ruberson, Jörg Romeis. Pest trade-offs in technology: reduced damage by caterpillars in Bt cotton benefits aphids. Proc Biol Sci. 2013 May 7 ;280(1758):20130042. Epub 2013 Mar 13. PMID: 23486438