Bt soya feeds pests

November 2014

Recognising the “critical” need to “improve our knowledge of the bigger picture of 'Bt' crop impacts, a Brazilian team has published a study on what seems to be an increasing problem in biotech crops in their country. 

The latest thing in GM soya is Monsanto's 'Intacta'. This crop generates a 'Bt' insecticidal protein, 'Cry1Ac', which is effective against moths, but doesn't work against 'armyworm', another key pest of soya. 

By comparing reproductive fitness of armyworm feeding on Intacta and on its closest 'isogenic', non-GM relative, the Brazilian team revealed small but pest-friendly differences in the GM soya. They found that larvae feeding on the GM soya matured more quickly and that the adult males arising from them lived longer. Moreover, the scientists established that these differences were not due to the armyworm filling up a niche left vacant by the decimation of Cry1Ac-sensitive pests, but were a result of “unintended changes in plant characteristics caused by insertion of the transgene”. 

A parallel investigation reported in the same paper found that Cry1Ac had no adverse effects on a wasp which parasitises armyworm eggs and provides a useful biological control for the pest. 

Monsanto, whose scientists participated in the study, now recommends that farmers growing Intacta soyabeans should release predators to control armyworm.

Those familiar with Monsanto and pro-GM lobby tactics in suppressing negative scientific findings on GM crops might be surprised that such a study was undertaken and published. It may well be, however, that the litigation culture created by Monsanto's habit of suing its own customers, has made the Company aware the tables might be turned on it: by identifying the problem, and its solution (neatly in the same piece research!) and making recommendations on that basis, it becomes the farmer's own fault if armyworm rampages out of control on his soya.

Apart from possible legal manoeuvring, the paper raises a number of other interesting GM issues.

Intacta is not just a Bt crop. It's in fact a novel hybrid of a Bt soya and a 'Roundup Ready' strain, genetically transformed to resist Roundup herbicide. The experimental plants weren't exposed to Roundup, but in a real-life field situation would be sprayed. Roundup alters plant physiology and there could be a whole set of different plant-pest interactions when the herbicidal treatment is superimposed on the Bt soya physiology. Exploring this issue is not suggested by the authors.

They did, however, mention that both the Bt and Roundup Ready soya lines had been found to have higher levels of carbohydrates and lower levels of protein than the parent non-GM lines, and that the question of any impacts on the GM plant's natural anti-herbivore defence systems have received little scientific attention. It's clear that neither GM strain used to create Intacta is “substantially equivalent” nor can the differences be considered “not biologically relevant”, the two main excuses for a positive risk assessment The appropriate tests simply haven't been done and the regulatory approvals of Intacta are unsound.

Intriguingly, the paper mentions “Increasing caterpillar problems faced by Brazilaian (soyabean) growers”. Most soya in Brazil is Roundup Ready. Is it the Roundup Ready part of Intacta which is underpinning the increasing caterpillar problem? If so, the Bt part of Intacta may be making a bad problem worse by feeding it better.


GM is a single-pointed answer to a multi-faceted question and will always generate enough unpredictable adverse side-effects to, not only cancel out the benefits, but to create other bigger problems.

Join TestBiotech in demanding withdrawal of EU approval of Intacta soya since there is an obvious need for safety re-assessment.


O. C. Bortolotto, et al., 2014, Development and reproduction of Spodoptera eridania (Lepidoptera: Noctuidae) and its egg parasitoid Telenomur remus (Hymenoptera: Platygastridae) on the genetically modified soybean (Bt) MON 87701 x MON 89788, Bulletin of Entomological Research
Unintended effects mighty be favourable to the spread of pest insects, TestBiotech 2.10.14

Richard Schiffman, Evil Monsanto Aggressively Sues Farmers for Saving Seeds, 20.06.13

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