Breakthroughs in biological crop protection: capitalizing on white-hot demand

10% of the global pesticide market

Already, bioinsecticides represent about 10% of the global pesticide market, and growth of bio-products (biofungicides, biopesticides, bioherbicides, biostimulants) is in the double digits. That’s no surprise if one looks at the demand. There are growing restrictions on chemical-based crop protection products, growing resistance to many chemical products and there are also risks and costs in testing and managing the residue that’s left behind with chemical products in some cases. Biological products avoid restrictions and residue and provide alternatives to chemical products for which resistance exists (but resistance may occur with some bio-products in future).

The number of bio-product start-ups has exploded in the last few years and the number continues to grow. As Dr Pamela Marrone of the California-based Invasive Species Corporation recently noted in the journal Biopesticide Science, “the exciting new technologies that these start-ups are developing such as RNAi, sterile pollen and systemic metabolites have potential to impact the market in 10 years or less.”

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Products are very powerful

It’s far from hyperbole, she says, to describe these new classes of products as revolutionary. “Years ago, we had the development of live microbe crop protection products, such as Bt, but with these new classes of technology, we have moved into biochemistry now,” she explains. “The products are very powerful as they are more targeted, in some cases much more targeted than chemical products, and of course come with less impact on the people applying the products and the other organisms in the environment.”

“Also, we have precedents being set to establish that they will be regulated differently than traditional chemical crop protection products. This is significant in lowering the time it takes to get a product to market. Yes, the development and marketing of these new products takes time and costs a lot of money, but it’s looking like the costs of regulatory approval will be much better.”

RNAi

Although only picking up steam now, RNA interference technology (RNAi) was discovered unexpectedly over 25 years ago by Dr. Craig Mello (RNA Therapeutics Institute at University of Massachusetts) and Dr. Andrew Fire (Stanford University), for which they achieved a Nobel prize in 2006. They found that cells have a search mechanism for DNA that can be harnessed (programmed) to silence genes involved in disease.

Similarly, in the bio-products realm, RNAi can be used to find and silence a gene that an insect pest or fungal pathogen relies on for survival. Last year, Scientists from Canada published a study on host-induced gene silencing. That is, the crop plant is modified genetically to contain a RNAi-induced mechanism, and the pest dies after ingesting the plant material. One well-known example is SmartStax Pro corn, approved by the US government to control corn rootworm.

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Acceptance is challenging

However, the Canadian scientists noted that acceptance of these plants “has been challenging due to general public concerns related to genetic engineering.”

RNAi can thankfully be used in other ways. Last year for example, a group of researchers in China published details on their successful control of two soil-borne pathogenic fungi in cotton and rice using a microbe grown in a beneficial fungus.

Stability of RNAi

You can also spray microbes that have been transformed to produce the RNAi, a technology platform referred to as Spray-Induced Gene Silencing or SIGS. The spray coating on the crop plant is eaten by the insect pest. One example is yeast cells transformed to carry an RNAi mechanism that kills spotted wing fruit fly, a type of yeast that naturally grows on the surface of rotting fruit that’s consumed by this fly.

However, not all insects are affected by eating RNAi. In addition, in cases where SIGS has been successful in treating some pathogens and pests, there can also be challenges with the stability of RNAi in the spray – but progress is being made in this area. Two years ago for example, a group of researchers from Spain, the US and Australia tested delivery formulation called BioClay with RNAi, and found that it prolonged SIGS control against Botrytis cinerea (a major fungal pathogen) in tomato and chickpea. They called it “a major step forward for the adoption of SIGS as an eco-friendly alternative to traditional fungicides.”

Peptides

Peptides (small amino acid complexes) are being created for a variety of purposes in bio-products and many other fields. Current AI and machine learning platforms can now easily search huge peptide databases for a configuration and composition that will interfere with a key metabolic process in a pest or disease pathogen. The appropriate peptide is then easily produced on a mass scale. However, there are challenges with efficacy after delivery and other aspects of peptides in crop protection.

Sterile pollen

Sterile pollen is just as it sounds. Pollen from specific weed species is irradiated to make it sterile and broadcast in a field to ‘pollinate’ female weed plants, but of course, the resulting seeds are not viable.

Systemic metabolites

As mentioned, an externally-supplied peptide or RNAi complex can cause the death of a fungal/disease pathogen or insect pest, but these compounds can also be produced by the pathogen/pest itself. That is, a bacteria or fungi designed to produce a metabolite poisonous to the target is introduced into the target, lives inside it (as an endophyte) and produces the poison until the target is dead.

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