- Author: Melissa O'Neal, Marrone Bio Innovations
- Author: Surendra K. Dara
The biopesticides market has been experiencing a rapid growth in recent years; however, plant- and microorganism-based biopesticides have been used for centuries for controlling pests. According to 17th century records, plant extracts such as nicotine were some of the earliest agricultural biopesticides used to control plum beetles and other pests (BPIA, 2017). Experimentation involving biological controls against lepidopteran pests were performed as early as 1835, during Agostine Bassi's efficacy demonstrations of the white muscardine disease caused by a fungus now known as Beauveria bassiana against lepidopteran pests (BPIA, 2017). Further, the use of mineral oils as plant protectants was cited in experiments during the 19th century (BPIA, 2017).
In the early 20th century, an increasing number of studies involving biopesticides emerged during the rapid institutional expansion of agricultural research (Stoytcheva, 2011). The bacterium Bacillus thuringiensis (Bt) was the initial biopesticide and has the most widespread use to this day. In 1901, Bt was isolated from a diseased silkworm by Japanese biologist Shigetane Ishiwata. Ten years later, German researcher Ernst Berliner rediscovered it in a diseased flour moth caterpillar (BPIA, 2017). Other commercial success stories from the 1980s and 1990s involve the use of Agrobacterium radiobacter to prevent crown gall on woody crops (Escobar and Dandekar, 2003) as well as utilizing Pseudomonas fluorescens for the prevention of fire blight in orchards with streptomycin-resistant pathogen populations (Stockwell et al., 2010).
Resurgence in academic and industrial research for biopesticide development occurred in response to rising costs associated with the overuse of synthetic chemicals. Increasing biopesticide adoption has resulted, in part due to rapid expansion of organic agriculture during the past decade (Eze et al., 2016). As a result, the development of new biopesticides has continued to increase since the mid-1990s. Over 100 active ingredients have been registered with the United States Environmental Protection Agency (USEPA) Biopesticides Division since 1995 (EPA, 2017). The increasing cost of developing chemical pesticides (Fig. 1) could also have contributed to the rise in biopesticide registration (McDougall, 2016).
Fig. 1. Costs to discover and develop a synthetic agricultural chemical. (Based on McDougall 2016)
Biopesticides currently represent approximately 5% of the total pesticide market (Olson, 2015). However, the biopesticides market is experiencing rapid growth of about three times the rate associated with conventional agricultural chemicals (Chandler et al., 2011). The trend toward the use of biopesticides is growing stronger for two major reasons; the first is the fact that biologicals alone and in combination with chemicals have the potential to provide superior yields and quality (Yadav et al., 2013; Dara, 2015 & 2016; BPIA, 2017;). Secondly, increasing regulatory restriction on chemicals has established restrictive barriers to bringing new products to market while countries such as Europe simultaneously are eliminating pesticide active ingredients at a rapid rate (Erbach, 2012) (Fig. 2).
Fig.2. Numbers of new agricultural chemical leads and launches from 1995-2010 (Based on data from Ag Chem New Compound Review, 2010).
Over 200 biopesticide products are currently sold in the US, in comparison to only 60 comparable products in the European Union. Overall, more than 225 microbial biopesticides are presently manufactured within 30 countries that belong to the Organization for Economic Cooperation and Development. Approximately 45% of the total biopesticide use occurs in USA, Canada, and Mexico, whereas Asia uses around 5% of biopesticides sold globally (Kumar & Singh, 2016).
According to Berkshire Hathaway, the global biopesticides market is projected to reach a value of $8.8 billion by 2022, representing annual average growth of 17% from 2016 (Brzoskiewicz, 2018). Primary growth factors affecting the biopesticides market include growth in crop production, ease of application, increase the in need for organic food, and growing preference for sustainable pest control methods. Although biopesticides currently account for approximately 2% of the plant protectants used globally, the growth rate indicates an increasing trend during the past two decades, wherein the global use of biopesticides is increasing steadily by 10% every year (Brzoskiewicz, 2018).
Biostimulants are a recent emergent area within which functionality and regulatory guidelines may not be as well-defined as those for biopesticides. A plant biostimulant is defined as “any substance or microorganism applied to plants with the aim to enhance nutrition efficiency, abiotic stress tolerance and/or crop quality traits, regardless of its nutrients content” (du Jardin, 2015, p. 3). Chatzikonstantinou (2017) regarded fertilizers and biostimulants as being a part of the same family, with reasoning based in their similarities for helping plants to simulate nutrients, boosting tolerance to abiotic stress factors, and increasing the quality of crops. There are currently no federal statutory definitions for biostimulants in the US, and uncertainty exists in both federal and state regulatory agencies in terms of how to develop guidelines for plant biostimulant categories (Russell, 2015).
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- Author: Melissa O'Neal, Marrone Bio Innovations
- Author: Surendra K. Dara
Biopesticides are based on naturally occurring microorganisms, plant extracts or other materials and are regulated by the United States Environmental Protection Agency (EPA)'s Biopesticide Division. Biopesticides have been safely used for over 63 years and are generally subjected to reduced regulation compared to conventional chemical pesticides.
Biopesticides can be developed from plant extracts or entomopathogenic microorganisms. Graphic: Surendra Dara
The active ingredient in microbial pesticides consists of a microorganism, such as a bacterium, fungus, nematode, protozoan or virus. While microbials are capable of assisting in the management of many different types of pests, each type of microorganism tends to be relatively specific for a target pest or group of pests. Biochemical pesticides are based on naturally occurring substances, which function by providing pest management through non-toxic mechanisms. Biochemical pesticides may function by disrupting or interfering with mating, such as in the case of insect sex pheromones or various plant extracts which serve as insect attractants used with traps. Conventional pesticides, by contrast, are generally synthetic materials that directly kill or inactivate the pest (Leahy et al., 2014).
Typically, samples of microorganisms or infected arthropods are collected from natural environments. Samples are taken to the laboratory and plated on media; thereafter, various colonies form from the collected samples. Individual colonies of interest may be selected, suspended, and examined for pesticidal activity during laboratory bioassays (Taylor, 1988). As part of the laboratory bioassay process, researchers screen candidates against a number of potential targets, which may vary widely, depending upon institutional goals and availability.
A key initial task is identification and characterization of the pesticidal compounds sourced from the plants or microbes collected in natural settings (Strobel and Daisy, 2003). Part of this process involves isolating and eliminating any compounds which have potential human health implications or may negatively impact non-targets organisms (USDA, 2017b). Additionally, analytical assays based on bioactive chemistry are developed to ensure quality control during the manufacturing process (Strobel and Daisy, 2003).
Several steps are involved with product and process development. First, user-friendly formulations are developed in both lab and pilot facilities. Next, manufacturing processes are developed and scaled in arenas including lab, pilot, and manufacturing facilities (Strobel and Daisy, 2003). Thereafter, field studies are conducted and data are gathered for the regulatory submissions which support product registration (USDA, 2017a).
Biopesticide registration process
A special committee has been established within the EPA due to the fact that it is often challenging to determine whether a substance meets the criteria for classification as a biochemical pesticide (Leahy et al., 2014). The Biopesticide Pollution Prevention Division (BPPD) of the EPA is charged with data review required for registration. Requirements for registration include acute studies consisting of oral, inhalation, intravenous, and dermal tests, in addition to eye and skin studies in rodents. A product chemistry review involving a five-batch analysis is also required by BPPD. Microbiology and quality control investigations assure that material is free of human pathogens. Ecological effects, including impact on non-target birds, fish, Daphnia, honeybees, lacewings, ladybeetles, and parasitic wasps is additionally determined. The review process is taken one step further during the endangered species review. Finally, the matter of the Exemption from Tolerance Petition for Food Use is addressed (EPA, 2017). It should be noted that efficacy data are required in addition to the aforementioned topics when attempting to register a new biopesticide in California (CDPR, 2017). There are several examples of successful pesticides which are sourced from natural products and registered as chemical pesticides (Fig. 1).
Fig. 1. Chemical pesticides developed from natural sources. Graphic: Melissa O'Neal
Abamectin is an insecticide/miticide derived from Streptomyces avermitilis, a microorganism found in soil. Its mode of action involves interference with neurotransmission (CDPR, 1993). Tebufenozide is an insect growth disruptor which interferes with insect molting hormones (Smagghe et al., 2012). The spinosyns are a family of chemicals produced by fermentation of Saccharopolyspora bacteria which are toxic due to disruption of neurotransmitters in both target and non-target organisms (Kirst, 2010). Azoxystrobin is a synthetic material derived from phytotoxic compounds which naturally occur in the mushrooms Oudemansiella mucida and Strobilurus tenacellus. Its mode of action is disruption of energetic reactions involving ATP synthesis (AgChemAccess, 2015). Finally, pyrethrins are naturally occurring materials derived from the chrysanthemum (Chrysanthemum cinerariaefolium) flowers and acts as a contact nerve poisons (Extoxnet, 1994).
The following tables 1-5 provide an overview of some of the commercial biopesticides currently registered in the US and other countries for controlling insects, mites, plant pathogenic fungi, and plant parasitic nematodes.
Table 1. Microbial insecticides andacaracides.
Table 2. Plant extract and oil insecticides and acaricides.
Table 3. Microbial fungicides.
Table 4. Non-microbial fungicides.
Table 5. Bionematicides.
AgChemAccess. 2015. Azoxystrobin. http://www.agchemaccess.com/Azoxystrobin.
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