The dicamba tsunami

October 2017

Much in the agri-news in June were reports from US farmers whose crops had been damaged by their neighbours' use of dicamba herbicide on the latest GM crops [1].

It seems Monsanto was over-eager to sell its new decamba-tolerant soya technology so that the GM seed hit the fields before the technical details for using it had been sufficiently developed. The result has been widespread injury not only to non-dicamba-tolerant soya, but to fruit and nut crops, specialty crops, and home gardens. Damage has been progressing so fast that as soon as the statistics were compiled they were out of date. As at 15th August 2017, complaints had been made in 21 States, affecting 3.1 million acres of soyabeans alone and inciting 2,242 official investigations.

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?).

GM plants grow polio vaccines

October 2017

World-wide, polio is now a disease of the past in all but two countries. The battle has been waged with mass vaccination programmes reaching, for example, 95% of infants in Europe. Even in Pakistan and Afghanistan, polio's last stand, the annual incidence has been reducing dramatically year-on-year and is down to a few tens of cases. Indeed, conquering this virus has been one of the great success stories of modern medicine.

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.

Dicamba and dust

October 2017

The major herbicidal chemicals used by US farmers haven't really changed very much over the decades. Various forms of 'dicamba', first introduced in 1967, and 'glyphosate', first introduced in 1974 , feature in America's agricultural landscape as much today as they did a quarter of a century ago.

Both these herbicides have a low acute toxicity to animals (you'd need to eat an awful lot before you'd drop dead). However, their properties, modes of action and applications are very different.

Dicamba selectively kills broad-leafed weeds, but not grasses. In 1994, 90% of the 27.6 million pounds of dicamba formulation used in US fields was applied to maize.

Glyphosate kills all plant life. Until the late 1990s, glyphosate was used to clear the ground before a crop was planted, and in 1995 27.6 million pounds of glyphosate-based weedkiller was used in US fields. Since then, usage has increased some fifteen-fold due to widespread planting of GM glyphosate-tolerant soya and later several other similarly-engineered major crops.

In a bizarre twist of fate, glyphosate's popularity has led to a "battle between farmers" and even a farmer's murder, caused by dicamba.

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?