What are natural pesticides?

Farmers who have traditionally depended on harmful chemical pesticides to combat pests are now shifting towards a new generation of natural biopesticides. However, the effectiveness of these alternatives remains uncertain.

Since the beginning of agriculture, farmers have faced challenges protecting their crops from pests.

In ancient Persia, which is present-day Iran, farmers used a natural insecticide called Pyrethrum, derived from dried Chrysanthemum flowers, to immobilize insects that harm crops – and later on, to eliminate head lice.

However, as the 20th century approached, large-scale monoculture agriculture began to rely on chemical pesticides containing arsenic, sulfur, or copper to repel pests from fruits, grains, and vegetables.

The use of these chemical pesticides has had significant effects on ecosystems and human health. That’s why some countries banned their use, and the EU has long contemplated – albeit unsuccessfully – a ban on glyphosate, a contentious herbicide that endangers biodiversity and links to cancer development. So, what is the solution?

Making natural pesticides

Production of biopesticides using plant-based ingredients such as Pyrethrum or essential oils from neem trees, as well as fungi that protect against pathogens, is gaining popularity worldwide as farmers move away from synthetic pesticides.

Neem trees, prevalent in India, actively produce limonoids renowned for their insecticidal properties, akin to those present in citrus plants. These limonoids act as a natural repellent against insects when used in the form of essential oils.

Natural pesticides, like those derived from neem trees, have proven to be effective in controlling pests such as locusts and preventing them from causing widespread damage.

Rosemary essential oil has also been shown to be a powerful deterrent against aphids, which can negatively impact the growth and appearance of various cereal and vegetable crops.

In Tamil Nadu, a farmer has replaced chemical pesticides with a homemade spray made from cow urine and locally grown leeks, resulting in thriving organic crops and improved health for the farmer.

Discovering the effectiveness of natural pesticides

In a recent study, Australian researchers highlighted the growing resistance of bluegreen aphids to chemical insecticides, a global concern. To combat this issue, the researchers suggested using non-chemical pest control methods, such as introducing natural predators like ladybirds and parasitoid wasps. Another alternative mentioned in the study is the use of novel bacteria to manage mosquito-borne diseases. The focus is on implementing region-specific solutions for pest control instead of relying solely on chemical pesticides.

Brazil, known as the largest soy exporter, is actively developing natural pesticides made from organic fungi and bacteria. The use of these natural microorganisms has proven to be effective in promoting the growth of soy crops while protecting them from pests and diseases. Additionally, Brazil is a significant exporter of corn and cotton and is the top consumer of chemical pesticides, as reported by the UN’s Food and Agriculture Organization.

Despite being the largest consumer of chemical pesticides, Brazil has seen a significant increase in biopesticide sales, rising from 4% of total pesticide sales in 2020 to 9% in 2022, indicating a shift towards more sustainable pest control methods.

Biopesticides offer numerous advantages

Microbial pesticides, which consist of microorganisms like bacteria or fungi, can control a wide range of pests, as stated by the US Environmental Protection Authority (EPA).

Among the most commonly used microbial pesticides are strains of the Bacillus thuringiensis bacteria. These strains produce a combination of proteins that can effectively eliminate various species of insect larvae.

One of the key benefits of biopesticides is that they are less toxic compared to conventional pesticides. They specifically target the intended pest and closely related organisms, minimizing their impact on other organisms, according to the EPA.

Unlike conventional pesticides, which can harm birds, insects, and mammals, biopesticides are applied locally and have a more focused effect.

Another advantage of biopesticides is that they are highly effective, even in small quantities, as highlighted by the EPA. Furthermore, they decompose rapidly, reducing the environmental exposure and pollution associated with traditional pesticides.

In addition to these benefits, natural pesticides can contribute to high crop yields. However, it is important to consider how a changing climate and increasing CO2 levels in the atmosphere may alter the relationship between certain plants and pests.