Breeding Bt crops breeds healthy pests

May 2022

In the first decade of 'Bt' insecticidal GM maize growing, it was noted that aphids unexpectedly thrived on them. Aphids are sap-sucking insects which can reproduce prodigiously under the right conditions, but don't usually cause economic damage to maize crops. It was suggested that these overwhelmingly 'right conditions' in the Bt maize plants might be their slight, but significantly, increased levels of amino acids*, dismissed by regulators as of 'no biological significance'.

Weak skinned Bt plants with Bt unfriendly viruses

May 2022

'Bt' insecticide-generating GM crops are sold as a major weapon in the battle against key species of pest without the need for chemical applications.

The initial benefits of Bt are eroded within a few years, not only by the evolution of resistance in the target pests, but by Bt-resistant non-target pests which are happy to fill the vacant seat at the monoculture banquet.

Early on, we had reports of out-of-control mealy bugs on Bt crops in India and Pakistan [1] and mirid bugs in China [2]. These are assumed to be the result of reduced spraying with broad-spectrum insecticides thanks to Bt.

However, there are some much more complicated environmental interactions going on. For example, mirid bugs were previously minor pests on cotton until the Bt GM version came along.

Nasty GM surprises

March 2020

Farmers' knowledge about the cycles of nature, their land, their crops and livestock, their soil, and all the life that shares their estates seem to have been swept aside by reductionist 'solutions' sold to them by corporations with $-lined technological tunnel vision.

Simple, GM 'solutions' have a habit of leading to complex outcomes and nasty surprises.

Scientific mindsets clash over GM mozzies

February 2020

At the end of last year, GM-free Scotland reported a study which found a significant presence of offspring of Oxitec's GM 'sterile' male mosquitoes flying around in areas of Brazil where a trial release had been carried out [1]. The object of the trial was to prevent dengue virus by eradicating its mosquito vector. The predicted "barrage of attempts to discredit the scientists and their science which seem to have become routine in response to any biotech-unfriendly research results" duly unfolded.

No surprise there, except that the attack on the study, including a demand for retraction, was led by one of the paper's own co-authors and supported by five of the others.

Mozzies ride the wind

January 2020

Efforts to control mosquito-borne diseases, such as malaria and dengue virus, have focused on eliminating the vector. Long-standing mosquito control methods have involved insecticides and removing the open bodies of water necessary for breeding. More recently, releases of GM sterile males [1], GM fungal pathogens [2], and self-destruct gene-drives mozzies [3] have been trialled.

Yet, paradoxically, even in areas where extreme reductions in the mosquito population have been successfully maintained, and even in areas where the surface water, vital for breeding, is absent for three to eight months of the year, malaria persists.

Non-GM cotton to the rescue

June 2019

GM cotton in India has probably been the biotech industry No.1 success story.

When the Indian government liberalised the economy in the 1990s, it pulled back agricultural subsidies on fertilisers, pesticides, water and seeds. Shops which had previously stocked a limited range of public agricultural goods were suddenly flooded with new, private brands.One of these was 'Bt' insecticidal GM cotton seed which was allowed into India for cultivation in 2003, followed by an upgraded version in 2006.

Both the yield per hectare and the area under cotton expanded dramatically, and there was a reduction in insecticide use ... for a while.  From an initial three types of seed on the market, by 2019, there were more than 1,200.

India became one of the world's top producers and exporters of cotton fibre, and Monsanto's GM cotton seed technology now dominates 90% of India's cotton acreage.

That's the macro-economic picture.  It suggests Bt cotton is a runaway success with Indian farmers and is delivering a good yield.

Let's think omnigenics

April 2019

You don't have to look too far to realise that the one, consistent, feature of all the products of GM technology is that they have failed to deliver on their promises.

In 1994, we were informed of an imminent series of world-changing GM crops destined to emerge in five-year leaps. Monsanto Vice President, Robert Fraley, listed 60 plant species which had already been genetically transformed. The first wave of GM crops would be pest-free, weed-free, and virus-proof by 2000. After this we would have GM improved foods on our tables by 2005, followed by pharmaceuticals from the fields by 2010, and finally GM-grown speciality chemicals.

The only limit to what was possible was the imagination of the genetic engineers, but the basis for this five-year leaping GM programme was never questioned, nor explained.

Now, over two decades later, how many of these leaps have actually been leapt?

Take horizontal gene transfer seriously - now

February 2019

The risk to health from artificial antibiotic resistance genes being used as markers during the creation of most GMOs was recognised in Europe back in the 1990s. However, lulled by mathematical modelling suggesting horizontal gene transfer (HGT) would never be significant in a complex, natural environment, the problem wasn't taken too seriously [1].

Non-GM maize gems

August 2018

US maize farmers have an arsenal of chemical weapons to fight their enemy No.1. But it isn't winning them the war.

'Western corn rootworm' grubs are munching away underground in maize crops in five US States. The worms are oblivious to the toxins applied to the soil, to the toxins applied to the seeds, and to the Bt toxins generated by GM plants themselves. Adult rootworm moths, which snip at the corn silks and prevent pollination, are equally oblivious to chemical attack.

Root feeding damage leads to reduced uptake of nutrients and water by the plant and instability, especially in adverse weather conditions. Yield losses can be catastrophic: western corn rootworm isn't called the "billion-dollar bug" for nothing [1].

No Bt soya for US farmers

July 2018

After spending more than a decade testing the performance of its GM 'Intacta 2 Xtend' soya in preparation for US commercialisation in 2021, Monsanto has pulled the plug.

Mega-pest moths

June 2018

A great deal of technical and commercial effort has been devoted to GM crops with soak themselves with their very own, self-generated 'Bt' insecticides.

Particular biotech industry targets for Bt have been cotton bollworm, a widespread pest in Africa and India, and corn earworm, a widespread pest in the Americas.

These 'worms' are actually the larvae of two related species of moth which cause billions of dollars of crop damage every year feasting on monoculture banquets.

Cotton bollworm is a particularly notorious pest, with a fast generation time, an extreme mobility, and an unusually diverse gene pool to draw on. It attacks over 100 crop types and has developed resistance to all pesticides used to try to control it. All in all, a top-class super-pest.

Frankenmoths RIP

October 2017

It's clear from the speed with which Bt-insecticide resistant pests are emerging that the hoped-for delaying tactic of telling farmers to plant non-Bt 'refuges' besides their Bt-generating GM crops to harbour wild-type susceptible pests just isn't working.

Biotech industry attempts to make its Bt crops easier for farmers to use by selling refuge-in-a-bag (RIB) GM seeds mixed with 5% non-GM seeds seems to have made the situation worse by diluting the level of insecticide present in the field [1].

Now, we have a new approach: refuge-in-a-pest (RIP?).

It's the bugs not the Bt

October 2017

Several varieties of 'Bt' insecticide are now widely generated by commercial GM crops.

These bacterial proteins are rarely directly toxic, but react with the gut lining of the target pest, creating a lesion in the gut wall. Death of the insect after 2 to 4 days, is a result of gut microbes leaking into the body.

Indeed, experiments have indicated that, for the majority of moth pest species, if their gut microbes have been destroyed by pre-treatment with antibiotics, Bt toxins are no longer able to kill them.

Putting this another way, death-by-Bt happens when the normally beneficial bugs in the healthy pests' gut move into the body where they become pathogenic.

Eating well keeps pests well

October 2017

GM crops which generate their own 'Bt' insecticides to kill their own pests are a key area of business expansion for the biotech industry. The biggest threat to these lucrative products is the emergence of Bt resistant pests.

Current wisdom in today's computer-dependent, gene-centric scientific world peopled with DNA-engineers, sees Bt resistant pests emerging due to a mistake in their DNA which accidentally produces a gene which accidentally interferes with the toxic effects of Bt and which they can pass on their offspring.

Based on the notion that pests would need two such 'resistance' genes to cope with Bt, the chance of it happening the field has been presumed slim, and the problem assumed to be a long-term one. Accordingly, biotech wise-guys, regulators and computer modelling came up with an anti-resistance strategy in which farmers plant non-GM 'refuge' crops beside the Bt ones to dilute out any chance mutant pests and their nuisance genes. As GM crops arriving on the market now come stacked with increasing varieties of Bt genes, the size of the 'refuge' crops has been allowed to dwindle.

And, is the wisdom working as it should?

GM pesticides cause more insect damage

September 2017

With such vast monocultures of GM corn being grown in America, most of which now self-infuse with the same or similar 'Bt' insecticides to kill the same or similar moth infestation, you might expect the pests to be reducing in abundance under the biotech-inspired onslaught.

Indeed, although no investigation has been made into the cause, earworm populations in American fields have been declining.  Long-term field monitoring from 1996 when the first Bt crops were entering the US landscape to 2016 found the pest reduced by up to 86%.

This should be good news for farmers, but counter-intuitively, over the same period, tests on sweetcorn sentinel plants [1] indicated an increase or no change in damage to both GM and non-GM plants.

The billion dollar bug

May 2017

In 1868 western corn rootworm (WCR) was observed in Kansas to be a harmless chewing insect from Central America found in low populations on the Western Great Plains.

*Note the naturally low numbers, and the suggestion that these beetles can naturally travel long distances. 

When centre-pivot irrigation with it's quarter mile watering radius (so efficient it's now sucking the plains dry) was introduced in the 1950s, maize monoculture madness gripped American farmers. Across the land, prairies were converted to horizon-scale corn fields.

To the WCR, which fed exclusively on corn and lay their eggs there, this became an 80-million acre banquet-plus-nursery.

All maize is wormy now

March 2017

If you've been following the GM issue for a while, cast your mind back to 2006. A long-standing, respected British science journal gave its "Outstanding Paper Award for Excellence" to a study which could be better described as a pro-GM PR initiative dressed up as science.

To assess what influenced consumer purchasing decisions, the study offered 'Bt' insecticide-generating GM sweet corn for sale in a Canadian farm shop beside conventional sweet corn. One of the more blatant exercises in propaganda used during this 'study' was the descriptors attached to the two types of sweet corn: the conventional one was labelled 'wormy' followed by a list of the pesticides sprayed on it; the GM one was labelled 'quality' with the 'Bt' (insecticide!) part kept separate.

Fast forward ten years and check out how these two sweet corns would truthfully be labelled today. The wormy one is still wormy and still sprayed with multiple pesticides. And the quality one?

New GM insecticide

December 2016

Photo: Creative Commons

Scientists at biotech company, DuPont Pioneer, have been busy searching around in the soils of America for an alternative to 'Bt' insecticides. These pest-killing proteins, whose ancestors came from Bacillus thuringiensis soil bacteria, have proved a marvellous money-spinner for two decades. Now, pest resistance to Bt toxins is rising, and even the new generations of GM crops with stacked Bt variants look like having a limited shelf-life.

DuPont has its fingers crossed that it's found a solution. Its scientists have found a previously uncharacterised protein, designated 'IPD072Aa', which just might serve its purpose.

Bt crops - a dead-end street?

November 2015

There's no escaping the fact that farming creates pests.  Nature's monocultures, such as the carpet of bluebells in the woods, choose a time and a place where they don't coincide with anything that might eat them, and can make themselves quite impalatable to passing diners.  Cultivated plants aren't so lucky: they have to grow where and when a human being dictates, and becoming a bugs' banquet is an occupational hazard they're not properly equipped to deal with. 

In the mid-1900s, synthetic pesticides revolutionised agriculture and crop fields got bigger and bigger.  Farmers' joy was short-lived: pests with resistance to the chemicals weren't long in arriving.  By the 1980s, completely susceptible pests had become uncommon, and new pesticides were thin on the ground. 

Then came another revolution in pest control: pesticidal plants which infused themselves from fruit to root with 'Bt' toxin to kill the pests stone dead. 

America creating agri-problems for itself

May 2015

Corn rootworm. Photo from Wiki Commons

In the cold light of the GM day, American farmers and regulators are being forced to recognise they've created a couple of problems for themselves.

Corn rootworm ranks amongst the most expensive threats to US maize farmers. The invention of a GM crop which generates its own 'Bt' insecticide against the rootworm has been a great boon.

However, bolstered by biotech enthusiasm to sell as much as possible of its product, farmers' enthusiasm for reduced post-planting workload and costs, government enthusiasm for incentives to grow maize, and limited availability of alternative seeds, US agriculture has been channelled into planting the same Bt crop year-on-year.

And the rootworm have, inevitably, evolved resistance to that Bt toxin.