Plant protection products (PPPs) are substances or micro-organisms having specific action through chemical or biological means which can control or destroy pathogens or harmful organisms. There is a broad range of PPPs that are biological in origin such as genetically modified plants, microbial biopesticide/biological pest control products to biochemical or plant extracts with active ingredients similar to a technical grade active ingredients (TGAI). An active ingredient is a chemical in a pesticide which can control pest activity. PPPs are used to cope with pathogen, pest and weeds. The active substance can influence non-target organisms, and harm the environment and humans. Plant protection products are active substances or preparations intended for (EC Directive, 1991):
- Protection of plant against harmful organisms.
- Impacting living processes of plants (different from nutrition).
- Control development and growth of undesired plants, plant parts.
Active substance in plant protection product is subjected to genotoxicity assessment before they can be used (Booth et al., 2017).
Plant protection products whether chemical or biological pesticides should be considered only when necessary with appropriate application techniques and understanding of the damage threshold. Pesticides are grouped according to the pest they control (fungicide, bactericide, insecticide, herbicide, rodenticide, molluscicide, nematicide etc.). Action of some pesticide may go beyond their group range affecting non-target organisms like soil microorganisms, worms, beneficial insects, birds, bees, plants, animals, aquatic organisms and humans.
Biopesticides are pest management agents that are living microorganisms or natural products. The microbial biopesticide (microorganisms working as a main active agent) affect only target pest and closely related organisms and are preferred over chemical pesticide as they may have less impact on the environment. On the basis of the active substance biopesticides may be of different types (i) micro-organisms (ii) biochemicals and (iii) semiochemicals.
The most widely used microbial biopesticide is the bacterium Bacillus thuringiensis (Bt), which produces insecticidal crystal protein (δ-endotoxin) during sporulation. These insecticidal crystal protein are toxic to insect pest. When they are ingested by the susceptible larva they bind to the midgut epithelial cell creating pores leading to cell lysis followed by death of the larva. Common biological control agent Trichoderma species. are an efficient antagonist and produce secondary metabolite which is of concern. Plant extract can be crude or a highly purified preparations similar to a discrete chemical TGAI. A wide variety of secondary metabolites are produced by the plants that deter herbivores from feeding on them. Some of these can be used as biopesticides for example, pyrethrins, an insecticidal compounds produced by Chrysanthemum cinerariaefolium (current species name Tanacetum cinerariifolium) (Silverio et al., 2009; Matsuda 2012) or neem oil an insecticidal chemical extracted from seeds of Azadirachta indica (Schmutterer 1990). Semiochemical is a chemical signaling agent produced by one organism causing a behavioural change in an individual of the same or a different species. The most widely used semiochemicals for crop protection are insect sex pheromones, some of which can now be synthesized and are used for monitoring, mating disruption or pest control by mass trapping (Reddy et al., 2009), lure-and-kill systems (El-Sayed et al., 2009).
Genetically modified (GM) plants possess novel combination of genetic material through the modern biotechnology expressing useful traits such as insect resistance, herbicide tolerance or disease resistance. The Codex Alimentarius Commission issued a guideline for the safety assessment of foods derived from recombinant-DNA plants (CAC 2003) that served as the regulatory requirements for the safety of genetically modified crops for human consumption. The Codex guideline does not specifically address genotoxicity but considers the new and altered levels of plant metabolites in genetically modified plants that can adversely affect human health. GM crop expressing any novel metabolite or pathway intermediates, requires genotoxicity testing (Booth et al., 2017). European Union (EU) emphasis on integrated pest management may lead to innovation in the way the biopesticides are regulated (Chandler et al., 2011). Only authorized biopesticide products may be used for crop protection.
Pogăcean and Gavrilescu (2009) discussed the benefit and risk of pesticide use, its impact on environment quality, human health and non-target organisms. Active substances in plant protection products are assessed within the EU and decisions on active substances are made at EU level. The new regulatory framework for plant protection products requires consideration on the impact of PPP on non-target species, biodiversity, ecosystem, including indirect effects on food web. Risk assessment is reviewed taking into account new regulatory framework and scientific development (EFSA PPR Panel Ockleford et al., 2017). The plant protection products basically are chemicals and therefore they should be used in a sustainable way.
References:
Booth, E. D., Rawlinson, P. J., Fagundes, P. M. and Leiner, K. A. 2017 Regulatory Requirements for Genotoxicity Assessment of Plant Protection Product Active Ingredients, Impurities, and Metabolites. Environ. Mol. Mutagen. (Special Issue: Applied Genetic Toxicology: From Principles to Practive) 58 (5): 325 – 344
doi: 10.1002/em.22084
CAC. 2003 Codex Alimentarius Commission. 2003 Guideline for the Conduct of Food Safety Assessment of Foods Derived from Recombinant-DNA Plants. Available at: http://www.fao.org/input/download/standards/10021/CXG_045e.pdf
Chandler, D., Bailey, A. S., Tatchell, G. M., Davidson, G., Greaves, J. and Grant, W. P. 2011 The Development, Regulation and Use of Biopesticides for Integrated Pest Management. Phil. Trans. R. Soc. B. 366(1573): 1987–1998
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EFSA PPR Panel (EFSA Panel on Plant Protection Products and their Residues), Ockleford, C., Adriaanse, P., Berny, P., Brock, T., Duquesne, S., Grilli, S., Hernandez-Jerez, A. F., Bennekou, S. H, Klein, M., Kuhl, T., Laskowski, R., Machera, K., Pelkonen, O., Pieper, S., Stemmer, M., Sundh, I., Teodorovic, I., Tiktak, A., Topping, C. J., Wolterink, G., Craig, P., de Jong, F., Manachini, B., Sousa, P., Swarowsky, K., Auteri, D., Arena, M. and Rob, S. 2017. Scientific Opinion Addressing the State of the Science on Risk Assessment of Plant Protection Products for In-Soil Organisms. EFSA Journal 15(2):4690, pp. 225
doi:10.2903/j.efsa.2017.4690
EC Directive 1991 Council Directive 91/414/EEC of 15 July 1991 Concerning the Placing of Plant Protection Products on the Market, OJL 230, 19.8.1991, 1–32
El-Sayed, A. M., Suckling, D. M., Byers, J. A., Jang, E. B. and Wearing, C. H. 2009. Potential of ‘Lure and Kill’ in Long-Term Pest Management and Eradication of Invasive species. J. Econ. Entomol. 102(3): 815–835
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Matsuda, K. 2012 Pyrethrin Biosynthesis and its Regulation in Chrysanthemum cinerariaefolium. Topic Curr. Chem. 314: 73-81
doi: 10.1007/128_2011_271
Pogăcean, M. O. and Gavrilescu, M. 2009 Plant Protection Products and their Sustainable and Environmentally Friendly Use. Environ. Engineering Manag. J. 8(3): 607 – 627
Reddy, G. V. P., Cruz, Z. T. and Guerrero, A. 2009 Development of an Efficient Pheromone-Based Trapping Method for the Banana Root Borer Cosmopolites Sordidus. J. Chem. Ecol. 35(1): 111–117
doi:10.1007/s10886-008-9580-6
Silverio, F. O., de Alvarenga, E. S., Moreno, S. C. and Picanco, M. C. 2009 Synthesis and Insecticidal Activity of New Pyrethroids. Pest Manag. Sci. 65(8): 900–905
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Schmutterer, H. 1990 Properties and Potentials of Natural Pesticides from Neem Tree. Annu. Rev. Entomol. 35: 271–298
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BIOLOGICAL PROCESSES- A NATURE'S GIFT 