Home » Toxic war on insects is costly and ineffective

Toxic war on insects is costly and ineffective

BY NICOLE MASTERS
2020 Healthy Soil Summit speaker

Taking a stroll through the 840 acres in New York’s Central Park, urban dwellers and tourists gain a soothing respite from the turmoil of the city. Views down the main promenade are arched with American elms vividly recalling scenes from movies like When Harry Met Sally and other blockbusters. The park contains over 20,000 trees, 280 bird species and a hum of insects. In 2003, this hum included the gnawing sounds of two invasive aliens: the Asian longhorned beetle and the emerald ash borer (pictured below).


Emerald ash borer beetle on leaf.
Emerald Ash Borer beetle.

These two pests have had a catastrophic impact, responsible for the deaths of millions of trees in North America, since their respective arrival in the 1930s and 2002. With their discovery in the park, New York City and 135 square miles surrounding the area, were put into immediate quarantine. The original infested trees, including their root materials, were removed and burnt: this was seen as the only effective control following infestation. With the iconic park’s image at risk, the decision was made to aggressively defend the trees using the neonicotinoid called imidacloprid. If you sat under a tree in Central Park between 2005 and 2007, you were guaranteed a close personal encounter with this neonicotinoid (neonic), with over 14,000 applications used, during that two-year spell[i]. Neonics, with their high solubility, were applied either as soil drenches or injected directly into the trees. Assumed to only target specific insect receptors, they were considered far safer than many other insecticides on the market at the time.

Book Cover: For the Love of Soil by Nicole Masters
Nicole Mastters is the author of For the Love of Soil: Future-Proof Strategies to Regenerate Food Production Systems.

In the early 1980s, there were three main broad-spectrum insecticides in use: organophosphates, carbamates and pyrethroids. With a heavy reliance on these insecticides, these chemical controls were becoming increasingly ineffective as pests developed resistance.[ii] Pesticide resistance has been explained by adaptation in a process called hormoligosis, the theory being, that with sub-lethal exposure, insects adapt and evolve to resist the chemical. Many scientists thought these dynamics explained the increase in pest insect pressures observed after spraying. However, the story is far deeper and more complex than this. In vibrant and alive ecosystems, there are checks and balances in place that mitigate whole-scale vegetation losses. In healthy functional ecosystems, many of these so-called insect pests and disease organisms provide beneficial services. Just as weeds are here to tell you something, so too are pests and diseases. 

During the 1980s panic, that growers would be unprotected against chemically-resistant insect hoards, and with growing awareness around environmental and human health risks, new systemic chemicals entered the world. As these pesticides move systemically inside the plant, manufacturers argued they would only target chewing insects. By using substances marketed as being far less dangerous, growers could breathe a sigh of relief. These pesticides could be applied prophylactically through the growing season, instead of exposing people and bees through aerial sprays. These pesticides are now used indiscriminately around the world in seed treatments, mixed with irrigation water, injected directly in trees, or applied foliarly (hopefully after the bees have gone to bed).  

The chemical war on insects is costly, toxic and ineffective.
Nicole Masters.

The systemic pesticides include groups of chemicals such as neonicotinoids and phenylpyrazole (fipronil). Fipronil is commonly used around households to control fleas, termites and cockroaches under tradenames like Frontline, Goliath and Termidor. Neonics were developed in the 80s, by the dream team of German multinational pharmaceutical company Bayer and Shell. Chemically similar to nicotine, they disrupt the nervous system of insects, resulting in “mad bee disease” and death. As neonics travel throughout the plant, they expose the innocent bystanders, known as “non-target insects,” through pollen, dew and nectar. A global analysis of 198 honey samples, found 75% of all samples contained at least one neonic.

Pesticides are the most inefficient of all the agrichemicals. It is estimated that at best 1 percent of these chemicals reaches their target sites, as nearly all is lost to run-off, spray drift or degraded in sunlight. In the case of neonics, only a tenth of the seed treatment is taken up by the plant, leaving the remaining 90 percent to impact on non-target species in soil, dust and waterways. 

Recent studies has shown that migratory birds ingesting, even low doses of neonics, become “anorexic,” losing 6-25 percent of their body weight and have costly delays to their migratory patterns. A study released recently on waterway health in New Zealand, should be ringing alarm bells for all; between 2 to 6 different pesticides were found in 78 percent of streams sampled. The organophosphate chlorpyrifos was found in most of these samples, this insecticide has a court order ban in the US and is banned for residential use in New Zealand and in many countries in the EU, including Germany. Ironically, this most widely used insecticide, is banned in its home country. Bayer continues to offer scientific assurances and shows dismay at the suggestions that neonics harm birds or bees as: “Bayer cares about bees.”

The timing of an explosion in neonic use in the mid-2000s, went hand-in-hand with the sudden collapse of bee, butterfly and bird populations. The Central Park treatments were celebrated as a success until, curiously, the treated trees began to turn yellow and lose their leaves. Closer inspections revealed a tiny spider mite, Tetranychus schoenei. Overnight, this mite, once considered a harmless herbivore, had turned into a raging beast, causing massive damage to the valuable trees. Initial assumptions were that the neonic wiped out the mite’s predators, the lacewings, ladybirds and parasitic wasps, turning a shackled monster free.

This phenomenon is not limited to elms. Other researchers discovered that following neonic applications, mite populations boomed between 100-200% percent in crops as diverse as corn, cotton and tomatoes. Mites are unaffected by the systemic pesticides as they lack the receptors that the neonics target. Measuring predator populations and other influences, did not explain why the mites began to produce nearly twice as many offspring. Researchers became curious. If it’s not a lack of predation influencing the population growth, they wondered, what could be the cause? In a breakthrough study, they uncovered a cascade of changes to the genes inside the trees themselves. The activity of over 600 genes were altered with the application of a single neonicotinoid. 600 genes! Many of these genes are responsible for cell wall structure, detoxification and the switching on of enzymes and phytohormones involved in defence. The neonics also increased the digestibility of nutrients, lifting available nutrition for the mites, resulting in an increase in the number of young. The insecticide created optimal conditions to weaken the plant and invite other pests to the table.

Many of the crude, broad-brush chemical controls have set agricultural systems up for the proliferation of pests and diseases. In a chemical arms race, it’s the insect pests who are winning the war. For every 1 pest species, there may be as many as 1,700 non-pest insects who have become the unintended causalities of this war. Insects provide a multitude of ecosystem benefits from pollination, nutrient cycling, decomposition and fueling the foodweb. The impacts from a looming “insectaggedon,” the collapse of insect species, is broad ranging, far-reaching and potentially catastrophic. Although non-target species, like bee and butterfly populations are collapsing, the crop pest species are flourishing. There are now over 550 insect species resistant to pesticides, including insects that have evolved to consume the Bacillus thurgensis (BT) toxin contained in engineered corn, cotton, soy and potatoes. Despite an increasing complexity of chemical controls, pests still consume 18-20 percent of the global crop and are becoming increasingly resistant to the controls.[iii]

With BT technology and targeted systemic chemicals, one could be forgiven for believing in the promised hype for a reduction in pesticides. Despite the benefits promoted by the seed producers, insecticide use has increased, not decreased, since BT technology was released.

In 2014, a public EPA memo stated, “published data indicate that most usage of neonicotinoid seed treatments does not protect soybean yield any better than doing no pest control.” Despite this information, these pesticides continue to be pushed upon producers around the world, as the gold standard in crop protection. Today half of soy and 79-100 percent of corn crops in the US are sown with a neonicotinoid pesticide. A 2016 review, applying whole systems accounting to pesticide use, found the benefit ratio falls below 1. Which means that for every benefit pesticides offer, there are 99 costs. These calculations include environmental and human health costs. In the U.S. alone, the direct and hidden costs of pesticides are estimated to be costing the U.S. economy over $37 billion every year. A total rethink on pesticides is urgently required.

A 2018 study in the U.S. corn belt comparing regenerative farms to conventional farms using insecticides, found ten times more insect pests in the conventional. Yup, you read that right, where farmers were applying their full arsenal of insecticides, genetically engineered, plants and seed treatments, there were 10 times more insect pests.

That there is a relationship between chemicals and pest pressures is not new science. Sixty years ago, agronomist Francis Chaboussou, from the French National Institute of Agricultural Research (INRA), was discovering that pesticides and fungicides were responsible for insect outbreaks. His work has largely been ignored. He hypothesised, that an insect would starve on a healthy plant, a phenomenon he termed as “Trophobiosis.” His book was published in 1985 and finally translated into English 20 years later under the title, Healthy Crops: A New AgriculturalRevolution. Chaboussou’s theory was that insects don’t attack all plants; it is the weakened plants with high amino acids and incomplete sugars that draw in pests like moths to a flame.

In Hawke’s Bay, New Zealand, the orchardist Nick Pattison can attest that after removing the pesticide Tokuthion from his programme, mealy bug numbers reduced in the first year, and the next year … they were totally gone. The pesticide was creating the conditions for the pests. In response to human health and environmental concerns around chemical use in the late 1990s, the New Zealand horticulture sector introduced Integrated Pest Management (IPM) strategies, which included hormone disruptors, pollinator strips, improved water management and accurate monitoring. One of the most effective strategies: stop using chemical pesticides! Growers became increasingly aware, that the insect pests were being attracted to disruptions in the trees. Why this information backed by measurable experience, did not flow outwards to other production sectors is baffling.

To address the concerns of growers around increasing pest resistance, many of these chemicals are now being used together to increase their efficacy, which also increases their harm to non-target insects due to synergistic effects in the environment. Research in the past decade, has been unveiling the insidious nature of even low concentrations of pesticides and fungicides on the environment, wildlife, bees, butterflies and on people.

How did soluble, persistent, broad-spectrum pesticides, pass reviews to be released with such gusto into the global environment? It could be argued that these pesticides did not follow a rigorous risk assessment process before being released. “Your risk assessment is only as strong as the question you ask,” says Jonathan Lundgren, the agroecologist and entomologist who led the 2018 Regenerative Ag study. He began his exploration into the adverse ecological impacts from pesticides in the late ’90s. His doctoral research became more complex and he began to realise that his inquiry into robust risk assessment processes opened a doorway he couldn’t close again. “I don’t think we can assess risk; the question is just too complicated. The effects are too broad. We don’t know which organisms are affected and in what way. How do you do science on 20,000 formulations? As soon as you add an adjuvant, the risk profile changes.” The risk assessment process has very little relevance to what happens outside of the lab. In the assessment process around the BT crops, no one asked the question “what would happen if all farmers changed to grow just one or two crops?” Wholescale biodiversity collapse is the answer; above and below ground.

This article is excerpted from Nicole Masters’s book, “For the Love of Soil: Strategies to Regenerate Our Food Production Systems.” Masters is an agroecologist and educator based in New Zealand.


[i] Szczepaniec, A., Creary, S. F., Laskowski, K. L., Nyrop, J. P., & Raupp, M. J. (2011). Neonicotinoid insecticide imidacloprid causes outbreaks of spider mites on elm trees in urban landscapes. PLoS One6(5), e20018.

[ii] Simon-Delso, N., Amaral-Rogers, V., Belzunces, L.P., Bonmatin, J.M., Chagnon, M., Downs, C., Furlan, L., Gibbons, D.W., Giorio, C., Girolami, V. and Goulson, D., 2015. Systemic insecticides (neonicotinoids and fipronil): trends, uses, mode of action and metabolites. Environmental Science and Pollution Research22(1),

[iii] Bass, C., & Jones, C. (2018). Editorial overview: Pests and resistance: Resistance to pesticides in arthropod crop pests and disease vectors: mechanisms, models and tools. Current opinion in insect science27,

Learn Soil Health from Nicole Masters

Nicole Masters will be presenting at the 2020 Healthy Soil Summit virtual event on Tuesday, Aug. 25. View the agenda here and register for the event!