James Theuri

Theuri

To achieve optimal crop yields, most growers use chemicals because of the instantaneous effect they provide in combating pests – insects, pathogens and weeds. Chemicals became particularly useful when industrial agriculture introduced mono-cropping, thus providing an arena concentrated with crop hosts for pests and diseases to invade with abandon. Consequently, chemicals were introduced and used blindly to combat these pests, without due regard for human and animal health, and the environment.

The most famous of the biologically-based pesticide products is Bacillus thuringiensis-based (Bt-based) microbial pesticide which has found favor for small farms, and particularly in organic food production. Other biopesticides include viruses, entomopathogenic fungi and bioherbicides, or minerals like acetic acid. Despite the success of Bt and other biopesticides, widespread adoption has remained marginal in favor of the more cost-effective synthetic chemicals. However, with more awareness of the many risks involved, commercialization of chemical pesticides is static or declining, while biopesticide research and usage is increasing. Indeed, the Environmental Protection Agency has been registering many chemical pesticides that are categorized as “reduced-risk” pesticides.

Benefits of biopesticides:

  •  Safety to applicators and other non-target organisms
  •  Ability to degrade quickly in the environment
  •  Low cost of research and development
  •  Suitability for integrated pest management (IPM)

Possible drawbacks:

  •  Short shelf life of products
  •  Inconsistency of efficacy within and between ecosystems
  •  Short field of residual life
  •  Difficulty of use; reluctance by users to change

Transgenic (genetically-modified) crops

Genetic resistance has been used for a long time as a pest management strategy; choice of crop variety with such could confer crop protection against disease and insect pests. Development time to incorporate resistance can take a long time – sometimes years - and in any case pathogens and pests can evolve to overcome the resistance. To overcome the time it takes for traditional breeding procedures, transgenic (gene insertion) technologies have been used for resistance against some pests. It involves the insertion of resistance genes from other plants without doing the time-consuming, cross-pollinations in the field.

Plant-incorporated-protectants are pesticidal substances that plants produce from genetic material that has been inserted to a plant. Transgenic plants are thus one of the contributions to the biopesticide family, and have found favor in both small and large farming operations. For instance, adoption of Bt-toxin corn was at a low of about 5% in 1995, compared to 2018 – when only 5% of the planted corn in USA was non-transgenic (USDA National Agricultural Statistics Service, NASS).

Generally, biopesticides are made of living things, or are extracted from living things; they are found in nature. Because of their safety to consumer and the environment, farmers are turning to non-chemicals for pest control – garlic oil to control aphids, soil fungi that are predatory on others, citronella oil to repel mosquitoes, and so on. Biopesticides are utilized more on smaller (and especially organic) farms where they are used as part of integrated pest management.

Clearly, the use of synthetic chemicals has been effective at managing pests. However, awareness of their dangers and development of resistance in target organisms is driving new research towards safer pesticides – biological pesticides (biopesticides), also known as “biorational” pesticides. In 1990, world biopesticide sales (mostly Bt toxin) were a paltry $120 million worth, and sales have been increasing since then by an average of 20% annually. Meanwhile, the chemical pesticide industry has been static, or even shrinking.

For sustainable agriculture, and more so in organic production, biopesticides fit very well. They do not always have the “silver bullet” effect provided by chemicals; however, they are safer for humans and wildlife, and degrade relatively quickly in the environment. By 2015, biopesticide use quadrupled from 2000, with nearly 18 million acres being treated in the USA (EPA, 2015). Biopesticides have gained the attention of leading agro-chemical companies, driven by consumer concern of residues on food, and development of resistance to chemicals by pests.

As world population continues to increase, so will the need for more food. Agriculture is undergoing rapid change to meet these challenges, while also being eco-friendly. Biopesticide products meet the demands of sustainability.

James Theuri is an agriculture and natural resources educator, University of Illinois Extension

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