Biopesticide refers to a pesticide which originates from animals, microorganisms, or plants. In addition to preventing yield losses through pest and disease control, biopesticides improve environmental and human health by contributing to the reduction of chemical pesticides as well as by improving the quality of produce (Popp et al., 2012). Additionally, these products have the potential to improve harvest and shipping flexibility, assist with environmental stewardship, and assist growers to achieve sustainability goals. Biopesticides are also important tools in integrated pest management (IPM) programs and reducing the risk of resistance to chemical pesticides (Pretty and Bharucha, 2015), improving worker safety through short restricted entry intervals (Valland, n.d.), conserving natural enemies, and maintaining environmental health (EPA, 2017a).
Biopesticides are inherently less toxic than conventional pesticides. Most affect only the target pest and closely related organisms, in contrast to broad spectrum conventional pesticides that may affect nontarget organisms such as beneficial insects, birds, wildlife, aquatic animals, and mammals. The majority of biopesticides often rapidly decompose, resulting in decreased exposure as well as preventing many pollution problems commonly associated with conventional pesticides. Although relatively safer than chemical pesticides, users or applicators should follow safety guidelines and wear personal protective equipment according to the label directions (EPA, 2017a). It is also important to follow guidelines for spray volume, application rates, droplet size, water pH, compatibility with tank-mix partners, time and frequency of application, and other details to ensure efficacy of the biopesticides (van Zyl et al., 2010; Wang & Liu, 2007; Whitford et al., 2009).
Biopesticides use has been increasing in the recent years. They can be used as standalone treatments or combined or rotated with other pesticides in both organic and conventional production systems. The fact that there are no residues is a huge benefit for exported commodities, as maximum residue limit issues continue to be a challenge in this arena (Berger, 2013).
In expanding upon the role of biopesticides in biocontrol, the topic of resistance management is a key consideration. Pest resistance to conventional chemical pesticides is a significant concern. Scientific research has repeatedly demonstrated that continuous use of the same class of pesticides, especially those reliant on a single mode of action, will result in the emergence of a pest population resistant to those products (Osteen et al., 2012). Populations of insect pests, plant pathogens, nematodes, and weeds all have the ability to develop resistance quickly, even to different types of functionally similar chemistries. This phenomenon is called cross-resistance and is caused by multi-chemistry detoxification mechanisms present in many pest populations (Horowitz and Ishaaya, 2009).
Because of the increasing number of novel, low-impact chemistries available, educators and growers have additional tools to manage resistance within IPM programs (EPA, 2017a). Biopesticides have long been used in combination with synthetic chemistries to provide the basis for excellent control programs that effectively manage resistance. Additionally, they typically have modes of action that are different from synthetic pesticides and do not rely on a single target site for efficacy. Properly used, these products have the potential to extend the effective field life of all products by curtailing the development of resistant pest populations (Horowitz and Ishaaya, 2009).
According to the United States Environmental Protection Agency (EPA), “IPM is an effective and environmentally sensitive approach to pest management that relies on a combination of common-sense practices” (2017b, p. 1). The University of California Statewide Integrated Pest Management Program (UCIPM) (2017) defines the IPM approach as combining prevention, cultural, physical, biological and chemical means to control pests, all the while minimizing economic, public health, beneficial as well as non-target organism, and environmental risks. Biopesticides are noted among the low-risk and most highly effective tools for achieving crop protection in IPM systems. The challenges of farming require that IPM systems actively integrate multiple management approaches to balance optima productivity with sustainability (BPIA, 2017).
Biopesticides should be considered as a component of a holistic total program and used at an appropriate time and pest density. Today, many forward looking IPM professionals are incorporating biopesticides into traditionally conventional pest management strategies (EPA, 2017b). However, education and training are needed to address biopesticide best use practices, the methods of integrating them into IPM programs; as well as instruction to promote an understanding of their unique modes of action (EPA, 2017b). Part of the educational process involves research through fair and realistic field trials that evaluate biopesticides both as standalone treatments as well as in combination and rotation with other options with an objective of improving IPM practices (Abler et al., 1992; Kumar and Singh, 2015). All of these learning experiences are useful in demonstrating the science of biopesticide use and establishing best use practices. A better understanding of biopesticide potential and the mode of action of different active ingredients, increased grant support to promote biopesticide research, and productive grower-industry-researcher collaborations to generate applied research data and design IPM strategies are necessary to make the best use of biopesticides and for environmental sustainability.
References
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