Botanical Pesticides and Their Mode of Action

Pest management is facing economic and ecological challenge worldwide due to human and environmental hazards caused by majority of the synthetic pesticide chemicals. Identification of novel effective insecticidal compounds is essential to combat increasing resistance rates. Botanical pesticides have long been touted as attractive alternatives to synthetic chemical pesticides for pest management because botanicals reputedly pose little threat to the environment or to human health. The body of scientific literature documenting bioactivity of plant derivatives to arthropod pests continues to expand, yet only a handful of botanicals are currently used in agriculture in the industrialized world, and there are few prospects for commercial development of new botanical products. Pyrethrum and neem are well established commercially, pesticides based on plant essential oils have entered the marketplace, and the use of rotenone appears to be waning. A number of plant substances have been considered for use as pest antifeedants, repellents and toxicants, but apart from some natural mosquito repellents, a little commercial success has ensued for plant substances that modify arthropod behavior. Several factors appear to limit the success of botanicals, most notably regulatory barriers and the availability of competing products (newer synthetics and fermentation products) that are cost-effective and relatively safe compared with their predecessors. In the context of agricultural pest management, botanical pesticides are best suited for use in organic food production in industrialized countries but can play a much greater role in the production and postharvest protection of food in developing countries. Botanicals have been in use for a long time for pest control. The compounds offer many environmental advantages. However, their uses during the 20th century have been rather marginal compared with other bio-control methods of pests and pathogens. Improvement in the understanding of plant allelochemical mechanisms of activity offer new prospects for using these substances in crop protection. I’m trying in this article to present different kinds of botanical pesticides came from different recourses and their mode of actions as well as I will try to examine the reasons behind their limited use (disadvantages) and the actual crop protection developments involving biopesticides of plant origin for organic or traditional agricultures to keep our environment clean and safer for humankind and animals.     

Regulatory problems associated with natural products and biopesticides

For registration, the United States Environmental Protection Agency (USEPA) separates pesticides into conventional chemical pesticides and biochemical and microbial pesticides. Natural products generally fall into the latter category. The USEPA has specified the test requirements for registration in the United States in the guidelines for registration of biorational pesticides (Subdivision M of 40 CFR Part 158). A discussion of the regulatory issues requires some reference to the accompanying scientific developments. The potential application of chemicals that affect insect behavior and development appeared an extremely promising approach to the reduction of adverse environmental and health impacts associated with many conventional pesticides. In addition to these benefits, the new biopesticides generally affected a very specific range of target species. However, although juvenile hormones and semiochemicals offer exciting new approaches to pest control, and are potentially valuable components of pest management strategies, acceptance of these techniques has been slow. Commercial development has been difficult for several reasons. Regulatory requirements may appear burdensome. Unconventional pest-control technologies may call for special formulations or application equipment. It may not be easy to establish the efficacy of non-lethal potential techniques. Investigators who derive funds from the public sector may have neither responsibility nor resources to carry the technology beyond the experimental stage. Because most activities in this field have been heavily research-oriented, few workers have possessed the additional resources to obtain safety data or data to satisfy regulatory requirements. Difficulties in preparing and administering guidelines for registration of biopesticides lie in the novelty of the pest control agents and the diversity of the techniques involved in their effective use. Rapid advances in molecular biology and other disciplines continually strain the capabilities of regulators who are responsible for making safety assessments regarding pest-control agents. Although regulatory authorities are familiar with conventional pesticides, safety assessment of biopesticides calls for totally different approaches.     

European Union policy on pesticides: implications for agriculture in Ireland

European Community (EC) legislation has limited the availability of pesticide active substances used in effective plant protection products. The Pesticide Authorisation Directive 91/414/EEC introduced the principle of risk assessment for approval of pesticide active substances. This principle was modified by the introduction of Regulation (EC) 1107/2009, which applies hazard, the intrinsic toxicity of the active substance, rather than risk, the potential for hazard to occur, as the approval criterion. Potential impacts of EC pesticide legislation on agriculture in Ireland are summarised. While these will significantly impact on pesticide availability in the medium to long term, regulations associated with water quality (Water Framework Directive 2000/60/EC and Drinking Water Directive 1998/83/EC) have the potential to restrict pesticide use more immediately, as concerns regarding public health and economic costs associated with removing pesticides from water increase. This rationale will further reduce the availability of effective pesticide active substances, directly affecting crop protection and increasing pesticide resistance within pest and disease populations. In addition, water quality requirements may also impact on important active substances used in plant protection in Ireland. The future challenge for agriculture in Ireland is to sustain production and profitability using reduced pesticide inputs within a framework of integrated pest management. © 2014 Society of Chemical Industry     

Authorization requirements for organisms as plant protection products in Austria

In Austria, beneficial arthropods and entomopathogenic nematodes ('macrobials'), as well as micro-organisms and viruses, are classified as active substances of plant protection products, according to the Federal Law on Transactions with Plant Protection Products which entered into force in 1991. Therefore, naturally occurring organisms, intended for use in the field of plant protection, must be authorized as plant protection products before they are permitted to be sold. Requirements for the authorization of macrobials, micro-organisms and viruses and the authorities involved are presented. The legislative regulations for the use of macrobials, micro-organisms and viruses as plant protection products are described. At the beginning of 1996, 35 plant protection products containing 21 different organisms have been authorized in Austria for use in agriculture, horticulture and forestry.     

Plant protection means used in organic farming throughout the European Union

Following the obligatory implementation of integrated pest management in the European Union (EU), the plant protection means suitable for application in organic agriculture attracted the attention of quite a wide group of potential users. In spite of the common rules of organic production, as well as the uniform principles of placing plant protection products on the market, the availability of products that can be legally used in organic crop protection differs significantly among the Member States. There is a uniform list of 10 basic substances that can be used in the protection of organic crops throughout the entire EU. Twelve Member States have official registers of plant protection products for use in organic agriculture, and the total number of qualified products per country varies from 11 in Lithuania to 576 in Italy. Some products that improve plant vigour or resistance and may be of use in protection of organic crops are placed on the market as biostimulants. They fall under the law that governs fertilisers and the systems of their registration vary widely among the Member States. In addition, there exist a number of products that have been legally introduced onto the markets of some Member States without registration as a consequence of a loophole in the law. The use of unregistered products in organic agriculture raises some doubts, but currently it seems that there is no legal basis on which to explicitly prohibit the practice. © 2017 Society of Chemical Industry     

Pesticidal natural products – status and future potential

There is a long history of using natural products as the basis for creating new pesticides but there is still a relatively low percentage of naturally derived pesticides relative to the number of pharmaceuticals derived from natural sources. Biopesticides as defined and regulated by the US Environmental Protection Agency (EPA) have been around for 70 years, starting with Bacillus thuringiensis, but they are experiencing rapid growth as the products have got better and more science‐based, and there are more restrictions on synthetic chemical pesticides. As such, biopesticides are still a small percentage (approximately US$3–4 billion) of the US$61.3 billion pesticide market. The growth of biopesticides is projected to outpace that of chemical pesticides, with compounded annual growth rates of between 10% and 20%. When integrated into crop production and pest management programs, biopesticides offer the potential for higher crop yields and quality than chemical‐only programs. Added benefits include reduction or elimination of chemical residues, therefore easing export, enabling delay in the development of resistance by pests and pathogens to chemicals and shorter field re‐entry, biodegradability and production using agricultural raw materials versus fossil fuels, and low risk to non‐target organisms, including pollinators. Challenges to the adoption of biopesticides include lack of awareness and education in how to deploy their unique modes of action in integrated programs, testing products alone versus in integrated programs, and lingering perceptions of cost and efficacy. © 2019 Society of Chemical Industry     

Products containing microorganisms as a tool in integrated pest management and the rules of their market placement in the European Union

Products containing microorganisms (bacteria, fungi and viruses) can be used in plant production as an intervention as well as a prevention method for pest control. Their utilisation is strictly in line with the principles of integrated pest management, provided that they are effective and safe. The rules of registration of microorganisms for crop production in the European Union differ, depending on whether they are placed on the market as plant protection products or not. For over 20 years, uniform rules for registration of plant protection products have been in force. Currently, 36 microorganisms marked up to the strain are approved for use in pest control in the Community. The decision concerning market placement of plant protection products containing approved microorganisms is issued for each member state separately. The approaches to market placement of other products with microorganisms differ within the EU, ranging from a complete lack of requirements to long and costly registration procedures. © 2015 Society of Chemical Industry     

植保无人飞机施用农药应用研究进展及管理现状

植保无人飞机是现代植保施药机械,具有作业效率高、精准、节水省药、灵活机动和对施药人员安全等特点,然而,与传统施药方式不同,其用水量少,喷施农药浓度高,喷雾易飘移,存在潜在的应用风险。目前关于植保无人飞机施药应用研究主要集中在雾滴沉积分布、飘移影响因素和防治效果评价等领域,有关其在膳食风险、环境风险和职业暴露健康风险评估等方面研究较少,且药剂登记和管理标准法规等相对滞后。为全面了解植保无人飞机施药应用以及管理现状,本文综述了植保无人飞机施药应用、风险研究及国际航空植保农药登记管理情况,总结了我国在该领域发展潜力和管理建议,以期为我国植保无人飞机安全施用农药和登记科学管理提供参考。     

Prospects and progress for Bacillus thuringiensis-based pesticides

Bacillus thuringiensis (Bt)-based insecticide products constitute the overwhelming majority of biopesticides but, despite having been commercially available for over 30 years, they have made little impact (<1%) on the crop-protection market as a whole. This has been largely due to poor cost-performance factors relative to synthetic organic pesticides. However, recent biotechnological advances—including genetic modification—combined with a variety of emerging opportunities, have created the prospect of the commercialisation of a new range of highly effective Bt-based biopesticides. Bioencapsulation of single-gene products—delta-endotoxins from selected Bt isolates—in killed Pseudomonad cells (Mycogen Corporation's ‘CellCap’ technology), offers a flexible delivery system with enhanced persistence. This versatile approach selects only the most appropriate biotoxins, which can be used to target a number of pest species. It is anticipated that Bt-based pesticides will continue to fill an increasing number of gaps in the panoply of synthetic crop-protection chemicals. Genetically modified products offer advantages in terms of efficacy, flexibility and safety but public concerns regarding perceived risks need to be addressed.     

Legislation for plant protection in Germany and in the European Union1

The first regulations on plant protection in Germany date from the last century and the first basic rules from 1937. New legislation was published in 1968. The key basis for modern plant protection is the Plant Protection Act of 1986. The legal basis, organization and scope of legislation i n the tield of plant protection in Germany are dcscrihed. The specific role of the rederal German states (Linder) is pointed out. The competent authority for granting authorization o f plant protection products in Germany is the Federal Biological Research Centre for Agriculture and Forestry in Braunschweig. The maximum period of authorization is 10 years. The legal basis for placing plant protection products on the market within the Member States of the European Union is summarized. together with the main elements of the regulations regarding authorization of plant protection products. There is a need for international cooperation to overcome foreseeable problem and workload regarding risk reduction in plant protection.     

Biologically active substances from higher plants: Status and future potential

Plant breeding and selection, husbandry techniques and crop protection technology, including agrochemicals, have all made substantial contributions to the present-day level of crop productivity. However, yield losses due to disease, pests and weeds must continue to be minimized in order to meet the food supply demands from an ever growing population. Appropriate synthetic chemicals are becoming increasingly difficult to discover and develop due to stricter requirements on efficacy, selectivity, toxicology and general environmental impact. Consequently, there is a growing interest in understanding and utilising natural mechanisms as the basis for crop protection products. Plants themselves are a rich source of biologically active substances which could potentially be harnessed to modify crop growth or to protect crops against disease and pests. This review describes briefly the current status of understanding relative to plant–plant (herbicide and plant growth substances), plant–fungal (fungicide) and plant–insect (insecticide) interactions. Future prospects are considered in relation to directed synthesis, cell culture, microbial pesticides and plant genetic engineering. The opinion expressed is optimistic and suggests that science today can be utilised to secure the food supply of tomorrow. However, utilising either natural products or molecular biology may require an improved understanding of crop physiology and new developments in agronomy. Therefore, the time-frame for major impact of the ‘new’ technologies on crop productivity may be longer than is commonly predicted.     

Principles for regulatory testing and interpretation of semi-field and field studies with non-target arthropods

This paper is a guidance document for side-effect testing with plant protection products on non-target arthropods under semi-field and field conditions. The principles, methods, endpoints and interpretation of non-target arthropod semi-field and field trials which should be conducted for registration of plant protection products in the European Union are presented and discussed. The recommendations presented reflect the opinions of the experts from authority, academia, industry and consulting which participated at the IOBC (International Organisation of Biological Control), BART (Beneficial Arthropod Regulatory Testing) group and EPPO (European Plant Protection Organisation) Joint Initiative workshop held in Versailles (France) on the 25–26 October, 1999.     

Principles for regulatory testing and interpretation of semi-field and field studies with non-target arthropods

This paper is a guidance document for side-effect testing with plant protection products on non-target arthropods under semi-field and field conditions. The principles, methods, endpoints and interpretation of non-target arthropod semi-field and field trials which should be conducted for registration of plant protection products in the European Union are presented and discussed. The recommendations presented reflect the opinions of the experts from authority, academia, industry and consulting which participated at the IOBC (International Organisation of Biological Control), BART (Beneficial Arthropod Regulatory Testing) group and EPPO (European Plant Protection Organisation) Joint Initiative workshop held in Versailles (France) on the 25–26 October, 1999.     

Biopesticides — harmonization of registration requirements within EU Directive 91/414 — an industry view1

A range of biopesticides (including, as active substances, bacteria, viruses, fungi, nematodes, protozoa and beneficial insects) is now commercially available for control of insect pests, fungal and bacterial diseases and weeds. The term biopesticide can include pheromones, insect and plant growth regulators, plant extracts, transgenic plants and macroorganisms as well as microorganisms. However, world biopesticide sales in 1990 were estimated to be 120 million USD, representing less than 0.5% of the world's agrochemical market. Out of this, approximately 90% of the biopesticide sales are represented by the bacterium Bacillus thuringiensis for the control of insect pests. Nevertheless, biopesticide sales are estimated to be increasing at 10–25% per annum and sales by the year 2000 are estimated to reach 1000 million USD. This paper looks at the current commercial status and the constraints that are facing industry concerning changing registration, particularly in Europe, the absence of harmonized data requirements, and the increasing costs and delays in registrations that deter the development of new biopesticides.     

Pesticide exposure assessment for surface waters in the EU. Part 1: Some comments on the current procedure

In 2001, the European Commission introduced a risk assessment project known as FOCUS (FOrum for the Coordination of pesticide fate models and their USe) for the surface water risk assessment of active substances in the European Union. Even for the national authorisation of plant protection products (PPPs), the vast majority of EU member states still refer to the four runoff and six drainage scenarios selected by the FOCUS Surface Water Workgroup. However, our study, as well as the European Food Safety Authority (EFSA), has stated the need for various improvements. Current developments in pesticide exposure assessment mainly relate to two processes. Firstly, predicted environmental concentrations (PECs) of pesticides are calculated by introducing model input variables such as weather conditions, soil properties and substance fate parameters that have a probabilistic nature. Secondly, spatially distributed PECs for soil–climate scenarios are derived on the basis of an analysis of geodata. Such approaches facilitate the calculation of a spatiotemporal cumulative distribution function (CDF) of PECs for a given area of interest and are subsequently used to determine an exposure concentration endpoint as a given percentile of the CDF. For national PPP authorisation, we propose that, in the future, exposure endpoints should be determined from the overall known statistical PEC population for an area of interest, and derived for soil and climate conditions specific to the particular member state. © 2016 Society of Chemical Industry     

Authorization of plant protection products containing microorganisms in the European Union1

The main principles concerning the authorization of plant protection products containing microorganisms in the European Union are explained: a positive list of microorganisms to be adopted by the Commission, authorization of individual plant protection products by the Member States according to common criteria and data requirements, obligation of mutual recognition of authorizations granted by other Member States subject to comparable conditions. Further detailed provisions are under preparation for the common criteria and data requirements as well as for the rationalization of the procedures for plant protection products containing genetically modified microorganisms.     

Current status of resistance in pollen beetle (Meligethes aeneus F.) to selected active substances of insecticides in Poland

Chemical plant protection is still an indispensable method in effective oilseed rape protection against the pollen beetle ( Meligethes aeneus F.) in Poland. This species is able to develop strong resistance against active substances used in synthetic insecticides. The phenomenon of pollen beetle resistance is currently found in many European countries. Therefore the objective of the study was to determine the present susceptibility level of Polish populations of pollen beetle to the main groups of insecticides recommended in Poland for pollen beetle control. The research showed high resistance of most tested Polish pollen beetle populations to many active substances of all chemical groups of insecticides applied in Poland.     

The use of entomopathogenic fungi for the control of stored-grain insects

The present contribution discusses the recent advances in the biological control of stored-grain insects with entomopathogenic fungi (EF). Thus, the effect of formulated vs. unformulated strains of EF and the effect of combinations of EF with other components, i.e. diatomaceous earths (DEs), chemical insecticides, natural products and natural enemies against stored-product insects are reviewed. Very few formulations of EF strains have been developed and used, of which invert emulsion formulation (water-in-oil type) is considered the most important. A synergistic effect of EF is produced by combining them with DEs, chemical insecticides and natural products but not with natural enemies belonging to arthropods. Moreover, since the action of EF against insect pests in general, and stored-grain insects in particular, is compatible with the food safety and environmental regulations, a good perspective for these biocontrol agents is expected as alternatives to synthetic insecticides. The potential areas of future research on the effective use of EF as biocontrol agents of stored-grain insects and the constraints that are associated with the registration and commercialization of EF as biopesticides under storage conditions are also discussed. Suggestions for the possible ways for implementation of this technology in storage systems are also provided in the present study.     

Efficacy evaluation of biological pesticides in the UK1

General principles of efficacy evaluation of plant protection products (both chemical and biological) in the UK registration system, under the Control of Pesticides Regulations 1986, are described. The UK perspective on efficacy evaluation of biological pesticides is discussed, highlighting differences and similarities between consideration of biological and chemical pesticides. Changes in efficacy evaluation of biological pesticides expected from implementation of the EU Directive 91/414/EEC are summarized.     

Framework for defining pesticide maximum residue levels in feed: applications to cattle and sheep

BACKGROUND

Pesticide residues in animal feed can endanger animal health and compromise the safety of livestock products for human consumption. Even though policymakers such as the European Union and the World Health Organization have established maximum residue levels (MRLs) for pesticides in both human food and animal feed, there is no systematic management of pesticides in animal feed that considers the entire supply chain. In response, we propose a framework for defining consistent MRLs for pesticides in animal feed that assesses the impact of defined MRLs on upstream (e.g., MRLs in feed crops) and downstream (e.g., MRLs in livestock products) sectors of the livestock-product supply chain.

RESULTS

The MRLs determined for the selected pesticides in the feed of cattle and sheep as case study animals indicate that lipophilic pesticides tend to have lower MRLs than hydrophilic pesticides, primarily due to the relatively high toxicity and biotransfer factors of lipophilic pesticides. In addition, we observe that, primarily for lipophilic pesticides, upstream and downstream regulations are not aligned in terms of defining MRLs in feed using current MRLs in crops with relevance to feed and foods of animal origin.

CONCLUSION

Some of the current pesticide regulations in the livestock-product supply chain need to be re-evaluated to ensure that MRLs in the upstream sector (i.e., crops) do not result in unacceptable residues in the downstream sector (i.e., MRLs in livestock products affecting animal and human health). Finally, we provide recommendations for optimizing the derivation of MRLs in feed, including the evaluation of residue fate during feed and food manufacturing processes. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.