Who’s the Pest Now?

Who’s the Pest Now?

“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 casualties of this war.”  Nicole Masters, agroecologist and educator based in New Zealand.

In this blog post, we summarise some of the concerns around insecticide use that are highlighted in Nicole Masters’ book, “For the Love of Soil: Strategies to Regenerate Our Food Production Systems”. This book equips producers with knowledge, skills and insights to regenerate ecosystem health and grow farm profits.

In the early 1980’s, three main broad-spectrum pesticides were in use: 

  • Organophosphates
  • Carbamates
  • Pyrethroids.

Agriculture relied heavily on these insecticides, but they were becoming increasingly ineffective as pests began to develop resistance to them. In response to growers’ concerns that their crops would be unprotected against chemically-resistant insects (along with increasing environmental awareness), new systemic chemicals were developed. 

Since these new insecticides move systemically inside the plant (instead of being applied through aerial spraying), manufacturers argued they would only target chewing insects, and were thus more targeted and far less dangerous.

Examples of systemic pesticides include groups of chemicals such as neonicotinoids and phenylpyrazole (fipronil).

  • Fipronal is used in households around the world to control termites, fleas and cockroaches. In 2018, Fipronal used by wine farmers was purportedly responsible for the death of about one million bees in the Cape.
  • Neonics are chemically similar to nicotine. They disrupt the nervous system of insects, resulting in “mad bee disease” and death. As these chemicals travel throughout the plant, non-target insects are exposed to them through pollen, dew and nectar. In a global analysis of 198 honey samples, 75% of all samples were found to contain at least one neonic.

But do they work?

According to Masters, pesticides are the most inefficient of all agrochemicals. 

  • At best, 1% reach their target sites
  • Nearly all is lost to run-off, spray drift or degraded in sunlight
  • Only 10% of neonic treatment is taken up by the plant, leaving the remaining 90% to impact non-target species in soil, dust and waterways.

What impact do these chemicals have on the environment?

As neonic use exploded in the mid-2000’s, so was there a sudden collapse of bee, butterfly and bird populations. The impacts of this are far-reaching, and potentially catastrophic. 

Insects provide a multitude of benefits in an ecosystem, including:

  • Nutrient cycling
  • Pollination
  • Decomposition
  • Feeding the food web.

Ironically, the use of chemicals can actually cause an increase in certain types of pests. For example, mite populations boom when their natural predators (lacewings, ladybirds and parasitic wasps) are wiped out. Because mites lack the receptors that neonics target, they are unaffected by the systemic pesticides. And that’s not the only reason they proliferate. 

In a breakthrough study, researchers uncovered that the activity of over 600 genes in the trees themselves was altered with the application of a single neonicotinoid. Many of these genes are responsible for detoxification, cell wall structure, and the switching on of phytohormones and enzymes involved in defence. Neonics were also found to increase the digestibility of nutrients, making more nutrition available for the mites and allowing them to multiply faster. In summary, the insecticide created optimal conditions to weaken the plant and invite other pests to the table.

It’s clear that broad-brush chemical controls have set agricultural systems up for the proliferation of pests and diseases. So, what’s the solution?

Healthy plants start in the soil 

Applying pesticides is a ‘quick-fix’, attempting to treat the symptoms, not the cause. Developing pest resistance starts by having a healthy soil, which produces healthy crops. Effective soil-management practices boost the natural defence mechanisms of plants, making them more resistant and/or less attractive to pests. 

At Zylem, we focus on providing sustainable soil health strategies that can significantly reduce the need for harmful chemical pesticides. 

Get in touch to find out more about our services and solutions: https://www.zylemsa.co.za/. Contact us on 033 347 2893 or send your enquiry to admin@zylemsa.co.za.

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