Herbicide tolerant GM soya is insecticidal too

June 2022

Glyphosate-tolerant GM crops aren't something that usually bring insecticides to mind.  Indeed, historically, US soyabeans were only sporadically challenged by insect pests.  Things changed around 2000 with the arrival of the soybean aphid which can only be controlled by foliar spraying.  Hot on the heels of this pest invasion came dramatic increases in bean leaf beetle which prompted the US Environmental Protection Agency (EPA) to issue an emergency exemption for neonicotinoid insecticidal seed treatments. 

By 2011, 34-44% of soyabean hectares in the US were treated with pre-emptive neonicotinoid seed coatings.  Scientists predicted this trend would continue and would be accompanied by an escalation of per-seed rates.

Paradoxically, although the bean leaf beetle populations have since waned, the use of neonicotinoid seed treatments has continued.  It's been pointed out that, due to the crops-for-ethanol boom in the US during 2004-2011, the cost of soya (and maize) seed doubled.  The presence of the insecticidal seed treatment seems to be perceived as a relatively cheap insurance for an expensive seed.  

Neonicotinoids don't stay on the seed surface: they disperse throughout the emerging seedling and hang around for a few weeks in the young plants before reducing to sub-lethal levels which persist for months. 

Sub-lethal exposure to toxins, such as neonicotinoids, comes with risks.  The pressure on pests to evolve resistance, and the resultant increase in quantity and variety of toxic agrichemicals used, is inevitable.  Insecticides which don't kill but weaken the species at vulnerable points in their life-cycle can be devastating to ecosystems.  Where the insects involved are pollinators, and so vital to three-quarters of our crops, their loss impacts directly on our agriculture and food supply.  

A wide variety of adverse human health effects of the glyphosate herbicide sprayed liberally on GM crops is being increasingly documented [1].  However, the impacts on wildlife of the increasing quantities and variety of other pesticides associated with the crops has received scant attention. 

An exception to this is the collapse of the iconic monarch butterfly population in America [2].  The GM contribution to this has long been identified as the absence of milkweed (the migrating monarch's sole food) around GM soya fields due to glyphosate spray-drift.  In addition to this, scientists have recorded neonicotinoid contamination in milkweed, presumably also from spray-drift as the soya is treated for aphids.  The levels of insecticide found were sufficient to adversely affect monarch larval growth.

OUR COMMENT

At the end of the day, glyphosate-tolerant GM crops are as profoundly damaging to animal wildlife as Bt insecticidal GM plants are.  Check out GM CROPS ADDING TO ECOSYSTEM COLLAPSE (May 2022) and take action.

Background

[1]  MICROBES ON THE CHOPPING BLOCK - May 2022

[2]  FLUTTERING INTO OBLIVION - March 2017

 

SOURCES:

• Claims of reduced pesticide use with GM crops are baseless, new study show, GM Watch, 4.04.15
• Jacob R. Pecenka and Jonathan G. Lundgren, 2015, Non-target effect of clothianidin on monarch butterflies, Science Nature
• Margaret R. Douglas and John F Tooker, 2015, Large-Scale Deployment of Seed Treatments Has Driven Rapid Increase in Use of Neonicotinoid Insecticides and Pre-emptive Pest Management in U.S. field Crops, Environmental Science & Technology

Photo: Monarch butterfly. Wikimedia Commons