These fungi can protect crops without the toxicity and carbon footprints of chemical pesticides
An estimated 20 – 40 percent of crop yield are lost to pests each year. Although synthetic insect-killing formulas have been the go-to solution since the 1960s, their dangers for human and ecosystem health are pushing some agtech companies to find organic solutions. Insect-combatting fungi is one of them.
One important advantage of natural insecticides is that it is more targeted than their synthetic counterparts. Synthetics don’t just kill unwanted crop pests but also their natural predators, which would normally keep populations in check. Synthetic pesticides are also indiscriminate when it comes to pollinator species like bees, whose populations have plummeted thanks to intensive chemical applications. In 2021, the UK government rolled back a blanket ban on synthetic pesticide Neonicotinoid to confront a particularly infectious strain of sugar beet virus spread by aphids. This underlines the urgency of developing organic alternatives to protect economically important crops.
Fungal pesticides could also reduce the greenhouse gas emissions associated with arable agriculture. Producing chemical pesticides releases nitrous oxide (a greenhouse gas more potent than carbon dioxide) as well as carbon dioxide and methane. Manufacturing conventional pesticides can even require more GHG emissions per kilo than fertilizers. Organic pesticides will become increasingly attractive to governments and agribusinesses facing pressure to cut carbon emissions in line with national reductions commitments.
Naturally evolved pesticide action
Many fungi possess natural chemical defences against pests. Most entomopathogenic fungi inhabit the soil and some have been used by farmers on a small scale for more than 150 years.
Upon encountering an insect, entomopathogenic fungi pierce their victims with cuticle-dissolving enzymes and thin, tube-like appendages, called hyphae. The fungi then invade the insect’s bodies with their hyphae, targeting muscle and fatty tissues. Some release natural toxins like Bassianolide, Destruzins, or Beauvericin, which poison the host. The insect dies within 3 to 14 days. The fungi then use the insects’ cadavers as anchors for new growth.
So far, over 170 pesticidal strains have been bio-engineered from 12 fungi species. By August 2017, the US had approved 11 strains of insect-killing fungi registered for commercial distribution. A few species dominate: Beauvaria bassiana has 33.9 percent fungal pesticide market share, M. anisopliae have 33. 9 percent, and Isaria fumosorosea and Beauvaria brongniartii 5.8 and 4.1 percent respectively. Most tests on mycopesticide effectiveness have been against common pests like aphids, whiteflies, thrips, and lepidopteran and coleopteran pests. As scientists have so far documented 750 fungi species that infect and kill insects and mites, there are probably many more fungal species waiting to be developed.
A typical mycopesticide product is Fargro’s Nautralis-L, based on B. bassiana and marketed as a bioinsecticide against whitefly, mites, thrips, and some fly groups. They also supply Mycotal, based on Lecanicilllium muscarium, a globally widespread fungus. It is effective against whiteflies, ahpids, and thrips. Originally developed for use in glasshouse cultivation, trials have shown success in outdoor field conditions. Koppert is one of the earliest organic pesticide manufactures, founded in 1967 by a Dutch grower interested in organic and sustainable agriculture. Another of their fungal-based agricultural inputs is Trianum-P, containing a fungal strain that combats plant-rotting fungi.
Certis is the US’ largest biopesticide manufacturer. Its long running market favourite is Botanigard, which also deploys the B. bassiana fungus against whiteflies and thrips. Their latest B.bassiana product is BoteGHA. On top of whiteflies and thrips, it target aphids and can be applied to outdoor crops. To support their new product rollout, the company has expanded its solid fermentation production capacity at its facility in Butte, Montana.
What is the future for mycopesticides?
Microbial pesticides, including fungal pesticides make up around 1.3 percent of the world’s total pesticide market. However, it is expected to see a compound annual growth rate of 12.3 percent between 2019 and 2024. This dwarfs the growth rate for the overall crop protection chemicals market in the same period.
There is already significant evidence that these organic pesticides work at scale. Brazil has mounted one of the most successful alternative pest management programs in the world and its IPM programme from the 1970s reduced synthetics by 50 percent in its high-intensity soybean sector through a combination of products containing viruses, bacteria, and fungi.
Ever since the 70s, Brazil has continued to strengthen its biopesticide sector. In 2020, it inaugurated a public-private partnership that established the country’s first research and development hub for biological pest control. Koppert, a global biological pest control manufacturer, is a key partner. Working with the São Paulo Advanced Research Center for Biological Control, Koppert will mentor and develop business plans for new startups entering the area. The project, known as Gazebo, has the support of corporate venture capital funds and is the largest centre of its kind in Latin America.
Many South and East African countries have been using microbial farming solutions for decades, including mycoinsecticide. The most widely-used mycopesticide on the continent of Africa has been Green Muscle, which consists of Metarhizium anisopliae fungus spores suspended in oil. This product has been deployed since the nineties to control locust outbreaks.
In the EU, widespread mycopesticide commercialisation and adoption might begin in earnest thanks to the Fark to Fork (F2) strategy, which launched 20th May 2020 under the region’s wider European Green Deal. In February 2022, Member States endorsed four legislative acts to make it easier for biological plant protection products containing microorganisms like fungi to be approved and authorised. In June 2022, the Commission proposed new legally binding targets under the Farm to Fark Strategy including a 50 percent reduction in the use of chemical pesticides. Crucially, the Commission have also proposed financial support for farmers to cover the costs of adhering to any new mandatory pesticide rules.
Current barriers to adoption
As with any other innovation, the switch to biological pest control takes time. Farmers demand extensive knowledge about new products and want to see effective results from long-term field trials before adoption. As a result, successful mycopesticide companies will need to pre- and post-purchase customer education and support to ensure the effective use of fungal pesticides.
European studies have shown that one of the most important determinants in whether a farmer will adopt biological pest management is the value they place on biodiversity and ecosystem services as bedrocks of cultivation. For this reason, potential interest in mycopesticides is also more likely to be higher among farmers that grow crops dependent on pollination, such as apples, berries, peas, and courgettes. A key part of expanding mycopestide demand and uptake is raising awareness around how chemical pesticides are harming environmental dynamics on which cultivation of these crops depend.
At the supply end, basic research is still needed to improve mycopesticide efficiency and to expand the range of target crops. A major question mark surrounds how the pest-killing efficacy of fungi varies with the changing biological, physical and chemical conditions of the outdoor environment. Changing environmental factors can either limit or extend the fungal strains’ ability to colonise crop plants and therefore protect them from pests.
Particular fungal strains will only colonise (and therefore be able to protect) certain species of plant. Specific fungal strains therefore need to be developed for different crop varieties. One obstacle to developing further strains is that many fungal species are difficult to identify, isolate, and cultivate.
Finally, while mycopesticides reduce many of the health and ecological risks of synthetic pesticides, more research is needed into the risks associated with applying insect-killing fungi at a large scale. The natural toxins released by commonly used entomopathogenic fungi, like the ubiquitous B. Bassiani, have been intensely studied. More work is needed on the substances released by less familiar species.
These technical difficulties track more general gaps in scientific knowledge about how to classify and manipulate members of the fungal kingdom. These gaps in the basic science of mycology and microbiology are directly relevant to advancing the mycopesticide sector. They will have to be addressed by innovators seeking to advance mycopesticide biotechnology further.
However, there are also promising indicators that biopesticides can become economically viable. Estimates for a new company developing, registering, and marketing a biopesticide are between $8-11 million. This is far less than for chemical pesticides, which range between £180-$200 million, even for an established R&D agrochemical multinational.
Compared to the impacts of synthetic chemicals, any health and environmental risks arising from mycopesticide agriculture do not seem insurmountable, especially since R&D is picking up. The Brazilian Gazebo private-public research hub offers a model for other countries looking to develop safe, competitive alternatives to synthetic pest control methods.