Biological Control for Plant Protection: Recent Advances in Research and Sustainability

Eco-friendly management of insect pests using sustainable measures is the need of the hour to prevent crop yield losses caused by pests. For sustainable agriculture, the use of biological methods, viz., botanicals, biological control, biopesticides, and pheromones for pest management, should be adopted and popularized on high priority. Chemical pesticides accumulate in the soil, disrupting its structure and fertility over time, causing long-term contamination and ecological imbalance. Biological control is a central component of integrated pest management (IPM), which constitutes an array of scientific methods adopted in both conventional and organic farming systems. The main objective of the study is to better understand the potential of botanicals in sustainable pest and disease management while maintaining ecological balance to assess the effectiveness of various botanical extracts or chemicals in eradicating specific pests, diseases, or weeds and to identify natural alternatives to synthetic pesticides and herbicides, thereby lowering the environmental and health dangers connected with chemical use. The study utilized search engines, research papers, online databases, and books, with data from various platforms contributing to this study. Unlike chemical pesticides, botanicals degrade quickly, hence enhancing soil health and maintaining rhizosphere microorganisms. They are cost-effective, non-toxic, and accessible for pest management. Botanicals are a sustainable alternative to agrochemicals that benefit soil health, protect microflora, and support organic farming. Plants, such as Azadirachta indica, Chrysanthemum, Pongamia, Lantana, Calotropis, Shorea robusta, etc., are used as botanicals. The development and utilization of botanicals in pest management offer an environmentfriendly and cost-effective approach. The focus should be on advancing wellresearched botanical solutions to promote sustainable agriculture. These botanicals can play a crucial role in integrated pest management (IPM) strategies. By integrating these natural solutions into sustainable agricultural practices, we can reduce reliance on synthetic pesticides, minimize ecological harm, and promote long-term agricultural productivity and soil health.

The decline of pest organisms (mites, insects, pathogens) population density by utilizing beneficial organisms demonstrates biological control. This is a very crucial component of sustainable agriculture that maintains production for a longer duration without environmental degradation. The utilization of biological agents should be enhanced in agriculture. This chapter basically discusses different varieties of biological agents that are being utilized for various types of pests in the agricultural field. Various types of biological organisms have been reported for successfully managing Diamondback Moth, Plutella Xylostella, Thrips, Mites, and soil-borne diseases in potatoes, hot peppers, cabbages, etc. Several species of Streptomyces, Trichoderma, Bacillus, Pseudomonas, etc., enhance plant growth and reduce the disease incidence, ultimately leading to enhanced plant yield. The awareness regarding hazards induced by chemicals in the agriculture field results in a significant increase in the use of biological control agents and a decrease in pesticide utilization. Biological control majorly depends upon factors like an abundance of biological agents, mass production, and field application for controlling pests, resulting in sustainable agriculture. The extensive knowledge of soil microflora ecology and factors affecting their population is crucial for deciding management strategies. The major strategies of utilizing microbial population in soil and biological seed treatment utilizing biological antagonists might be some alternatives that move the concept of sustainability a bit closer to reality. By utilizing the above-mentioned approaches, sustainable agriculture will help in reducing the use of synthetic pesticides and their adverse impact on the environment, improving the safety of farm workers and maintaining the economic viability of crop production. The current work includes a compilation of various diseases associated with plants and the utilization of bacterial agents such as Bacillus, Pseudomonas, Actinomycetes, etc., for sustainable agricultural practices.

Since the global human population and the demand for food are continuously growing, the use of chemical fertilizers such as urea, ammonium sulfate, calcium nitrate, and diammonium phosphate has become more prevalent in agricultural practices. While these fertilizers initially boost production, their prolonged use can have detrimental effects on soil health and human well-being. Increased application of these agrochemicals often leads to soil degradation, environmental disruption, and pollution of groundwater. The overreliance on conventional chemical fertilizers disrupts soil ecology, decreases soil fertility, and poses risks to human health. To address these issues, biofertilizers offer a promising alternative. Biofertilizers are natural substances containing living microorganisms that enhance soil quality and plant growth. Upon their application to seeds, plant surfaces, soil, or the rhizosphere, they supply essential nutrients and suppress harmful microorganisms. Biofertilizers improve plant growth by a variety of mechanisms, which include phosphorus solubilization, biological nitrogen (N2 ) fixation, and the synthesis of growth-promoting compounds. They contribute to sustainable agriculture by preserving soil health and promoting plant yields. This review will explore the different types of biofertilizers, their effects on plants, and their potential for future use in agriculture. By examining their functions and benefits, the review aims to highlight the role of biofertilizers in advancing sustainable agricultural practices.

In the past few decades, agriculture has been revolutionized by the use of chemicals for crop protection. However, their widespread and long-term use resulted in insecticide resistance and biomagnifications of insecticides, which in turn resulted in restrictions on their export. Several environmental issues, like soil and water contamination and dramatic increase of harmful residues in many primary and derived agricultural products, have been raised, which affect human health. Therefore, there is an urgent need to promote the use of alternative methods of crop protection. Efforts are being made to develop biorational pesticides that are environment friendly. Biorational pest management involves biocontrol agents, botanicals, microbial biopesticides, insect growth regulators, and genetically engineered bio-pesticides, which have relatively higher performance and pose a lesser concern about environmental toxicity. The resistance to biopesticides in target organisms was not easily generated, unlike in many cases of their chemical counterparts. Although numerous naturally occurring biopesticides have been tested or even commercialized in a few cases, their use has not expanded as greatly as their development. Their global use has been hampered by various constraints such as slower speed of kill, narrow host range, product stability, etc. To address some of the above problems, biotechnological approaches like genetic engineering are being explored. This technology has led to the commercial production of genetically engineered (GE) crops on approximately 250 million acres worldwide. The present chapter highlights the recent progress in the production and utilization of biorational pesticides. Further, their types, genes/bio-active agents involved, their mode of action and environmental concerns have also been discussed to provide an up-t- -date and holistic view of the recent development in the production of biorational pesticides.

Plant disease management and the use of synthetic chemicals have walked hand in hand for many decades. However, the excessive use of these agrochemicals has led to environmental pollution, ecological imbalance, and the emergence of resistant pathogens, along with harmful effects on non-target insects and human health. Therefore, scientists have diverted their attention toward finding safe and suitable alternatives for microbes. Many microbes are known to have antagonistic effects on various phytopathogens. These antagonists thrive as soil microflora or as endophytes in the rhizosphere or phyllosphere. They also inhabit harsh conditions like volcanic areas, high altitudes, marine ecosystems, etc. Out of the above-mentioned habitats, antagonistic microflora is majorly found in soil and plant rhizospheres. These antagonists are known as ‘biological control agents’ (BCAs) as they have an inexplicable capacity to control various plant pathogens. Among these biocontrol agents, actinobacteria hold considerable importance and are known to produce a diverse array of secondary metabolites and still are an inexhaustible natural source of antibiotics. They also produce various antifungal enzymes like chitinases and glucanases, which contribute to their antifungal properties. Additionally, they also act as PGPRs and help in nutrient uptakes for better growth of the host plants, thereby increasing crop yields. Thus, these bacteria exert both direct and indirect effects on the host plants and play crucial roles in plant growth promotion. Out of all actinobacteria, “Streptomycetes” are the most commercially harvested bacteria, contributing toward at least 60% of the available compounds of agricultural interest. In addition, actinobacteria are also associated with enhancing the plant immune response prior to infection, which provides resistance against subsequent challenges by a pathogen, known as induced systemic resistance. Accordingly, actinomycetes should be used to enhance the defensive capacity of plants and can, therefore, be an alternative to synthetic chemicals and establish a sustainable strategy to control phytopathogens. Several commercial products obtained from actinobacteria are available in the market but they are just the tip of an iceberg. Therefore, ’actinomycetes’ constitute a promising future and a vast scope for scientific and commercial exploration for the development of new biocontrol agents. Thus, this chapter attempts to provide an overview of the present understanding of actinobacteria and their potential as a biocontrol agent, their mechanism, application, and an alternative for sustainable crop protection.

In India and tropical Asia, insect pests are one of the most significant limiting factors for vegetable production, with Lepidopteran pests causing the highest damage. Vegetables are among the most profitable crops, and farmers all over the world recognize the need to protect them from damage by insect pests. Diamond-back moth (DBM) on cabbage (Plutella xylostella), fruit borer on tomato (Helicoverpa armigera), pod borer on chili (Spodoptera litura), shoot and fruit borers on brinjal (Leucinodes orbonalis), and the fruit borer on okra (Earias fabia) are some of the most common insect pests on vegetables. Although a vast range of chemical pesticides have been used to control lepidopteran pests, which are very effective too, increased knowledge of the harmful effects of pesticide usage on the environment and human health has resulted in better awareness and decreasing dependence on chemical controls in recent years. Biological management of pests utilizing their natural enemies is, therefore, considered the most effective alternative to chemical control. There are over 230 species of natural enemies, which are commercially accessible and employed in augmentative biological control. It is not always easy to ensure the efficacy of these natural enemies, as their performance as biocontrol agents is influenced by a variety of abiotic and biotic factors, including unfavorable climatic conditions, the presence of chemical pesticides, potential predator attack, the presence of plant defense mechanisms, and the negative effects of unwanted breeding selection and inbreeding in mass-rearing programs.
Therefore, keeping the above points in mind, the objective of the present study is to focus on recent advances in biocontrol strategies for lepidopteran pests by utilizing genomic information. Over the last century, academia and biocontrol firms have been interested in finding new indigenous natural enemies as well as in exploring the possibility of improving the efficacy of potential biocontrol products. This chapter will cover a wide range of advanced methods and technologies like mating disruption technology, RNAi as pest control and a sterile insect technique, etc., using genetic and genomic knowledge to develop better biocontrol agents, a process known as ‘next generation biocontrol’.

Recent scientific interest in the biological control of plant-parasitic nematodes (PPNs) has surged due to successful control attempts and the harmful effects of chemical nematicides. Chemical-based plant protectants, while effective, pose risks to both environmental and human health. By contrast, biological control offers a natural alternative that avoids introducing artificial substances and significantly minimizes the chance of resistance development in nematodes against their biological antagonists. Biological control involves using various living organisms, such as fungi, bacteria, viruses, predatory nematodes, micro-arthropods, annelids, protozoa, and other generalist predators, as biocontrol agents to manage PPN populations. These agents work to both suppress nematode populations and prevent disease, fostering healthier plant growth and development. Biological control not only prevents the development of a disease, but it also suppresses the population of plant-parasitic nematodes and thus has a beneficial impact on plant growth. Over time, as more biological control agents are developed and their application becomes more effective, they can potentially replace chemical nematicides entirely. The present chapter explores the various biocontrol agents that target plant-parasitic nematodes, detailing their mechanisms of action, such as infection, predation, and competition. Additionally, it addresses the potential of integrating these biocontrol agents into sustainable agricultural practices, providing a holistic approach to managing PPNs in diverse cropping systems. Through these efforts, biological control can help reduce the dependency on synthetic chemicals, offering a safer and environment-friendly solution for enhancing agricultural productivity. The present chapter, therefore, besides highlighting the economic importance of nematode infestation in crop plants and their various characteristics, also highlights the importance of using biological control in the management of plant parasitic nematodes, thereby reducing the population of plant-parasitic nematodes. This novel strategy of using different groups of living organisms, including fungi, bacteria, viruses, predatory nematodes, micro-arthropods, annelids, protozoa, and generalist predators as the biocontrol agents, has been discussed in detail for the management of plant parasitic nematodes in an environmentally sustainable manner. In addition, the mechanisms of action of these biocontrol agents have also been discussed in detail.

Plant-parasitic nematodes (PPNs) rank among the most devastating plant pathogens, inflicting substantial economic losses in agriculture. While synthetic chemical nematicides are often employed as an effective control measure, their detrimental effects on non-target organisms and ecosystems underscore the urgent need for environmentally sustainable and eco-friendly alternatives. Plant roots naturally produce a wide array of metabolites with defensive properties, highlighting the importance of understanding root-mediated interactions between plants and nematodes as a foundation for managing these harmful pests. This book chapter delves into the potential of botanical solutions for combating PPNs. Botanical amendments, including plant metabolites and extracts, have emerged as valuable tools, serving dual roles as organic fertilizers and nematicidal agents. These amendments suppress nematode growth and development by releasing nematicidal compounds, exhibiting antagonistic effects, and enhancing plant resistance by modulating plant physiology. Furthermore, breeding programs aimed at developing resistant crop varieties through the incorporation of resistance genes present a promising avenue for nematode management. The chapter emphasizes the integration of organic agricultural practices to foster sustainable ecosystem management, enhance plant productivity, and utilize cost-effective, eco-friendly botanicals for the efficient control of phytonematodes.

Biocontrol of weeds makes use of instinctive living creatures, viz., insects, animals, disease organisms, phytophagous fishes, insects, fungi, bacteria, nematodes, and several other animals, to restrict their growth and expansion. Using biocontrol, the population of weeds can be lessened up to a fair extent, but the eradication of weeds is not attainable. The biocontrol method is generally used against serious, exotic/introduced weeds, but it also has the potential to work well against other types of non-dominating weed species. Biocontrol of weeds is environmentally safer, because it has no residual effect, is more economical, has enduring effects, is non-dangerous to untargeted species, and effectively controls the weeds in uncultivated land/areas. Except this, some aquatic and other water-loving organisms (like snails and fishes etc.) convert the underwater weeds into seafood resources for the food chain. Therefore, this eco-friendly technique should be encouraged and utilized to a larger extent to encounter the present and upcoming obstacles in weed control in agroecosystems. A large number of biocontrol agents may be utilized in the biocontrol methods; however, their careful evaluation and environmental impact assessment before their commercialization at a widespread level are always required. The present chapter is, therefore, an up-to-date compilation of the recent, diverse biocontrol techniques used for weed control alongside the traditional examples of weed biocontrol to present it as an environmentally safer method of weed management and an integral part of sustainable agriculture.

The use of entomophagous organisms, including parasitoids and predators, for the biological management of insect pests presents an ecologically advantageous and economically feasible approach to achieving sustainable crop production. Traits such as tolerance to pesticides and other abiotic stresses, shortening the developmental period, increasing progeny output, changing sex ratio, and changing host or habitat preferences can be improved through genetic manipulation to increase the effectiveness of these natural enemies. The majority of genetic improvement of entomophagous and other biocontrol agents focuses mainly on pesticide tolerance or resistance, while a few attempts have been made to improve the other aspects also. When the implementation methods are adequately developed, the critical qualities limiting their effectiveness can also be discovered, and the enhanced insect strains may retain their fitness in the natural environment. Artificial selection of multiple strains under varied environmental conditions and their hybridization has been reported. Considering the advancement in insect biocontrol methods, the applications of recombinant DNA technology include introducing foreign genes into insect baculoviruses and attaining quick and efficient expression in recipient host systems. This chapter highlights the various applications of genetics in improving the fitness and usefulness of these beneficial insects, including case studies, recent advancements, and the possibilities for real-world implementation in pest management strategies. Genetic enhancement of biocontrol agents (BCAs) has the potential to be very successful, resulting in the generation of more improved strains with the desired level of effectiveness, host searching ability, broad host range, and persistence in adverse environmental conditions, thus giving a vital tool for sustainable pest management. Moreover, this chapter aims to contribute to the development of new and long-term pest management strategies by utilizing available and recent biotechnological approaches.

Seasonally, numerous invertebrate and microbial species are utilized in augmentative biological control (ABC) to combat pests across more than 30 million hectares globally. In Europe, agents of biological control in invertebrates dominate the market, although North America leads in the use of microbial agents. Latin America and Asia are also experiencing significant growth in ABC, particularly in microbiological applications. The rising popularity of ABC is due to several factors: (1) Its inherent benefits, including safety for agricultural workers and nearby residents, absence of a harvest waiting period post-agent release, long-term effectiveness because they are not resistant to their natural adversaries, arthropods, decreased amount of pesticide residues below the maximum levels (MRLs), minimal phytotoxic effects, enhanced yields, and healthier crops; (2) The professionalism within the biological control industry, characterized by cost-effective mass manufacturing, stringent quality assurance, effective packaging, shipping, and release techniques, and the availability of more than 440 pest control chemicals; (3) Recent achievements demonstrating biological control capacity to safeguard agriculture when pesticides fail or are inaccessible; (4) Demands from NGOs, customers, and merchants for pesticide residues much below the permitted maximum residual levels; and (5) New regulations in some areas that try to cut back on or switch to sustainable pest control techniques in place of synthetic pesticides. Despite its current usage, ABC has the potential for much broader application. We advocate for a pragmatic, flexible agricultural approach that integrates diverse agricultural and pest management strategies. Moving forward, we propose "Conscious agriculture", which entails everyone's active involvement in the production and consumption chains, with a commitment to environmental sustainability and future resource conservation. The adoption of “conscious agriculture” can significantly enhance the future prospects of ABC as a credible alternative to conventional farming.

Fungi produce a diverse array of mycotoxins, which are secondary metabolites that exhibit varying degrees of toxicity to animal species. While many mycotoxins pose significant health risks to humans and animals, necessitating stringent global regulatory measures, others exhibit selective toxicity, making them promising candidates for biocontrol applications. Mycotoxins with narrow host ranges and minimal toxicity to humans and plants hold particular potential for use in ecologically sustainable pest management. In natural ecosystems, insects often encounter these fungal metabolites while feeding on infected plants, offering a natural avenue for their application in agriculture.
Insects not only inflict substantial economic losses by damaging crops but also act as vectors for plant viruses, exacerbating agricultural challenges. Harnessing the insecticidal properties of mycotoxins represents an innovative and environmentally friendly approach to pest control. These toxins disrupt insect physiology through specific molecular and biochemical mechanisms, which, when elucidated, could inform the development of advanced pest management strategies. For example, integrating mycotoxins into genetically engineered insect-resistant transgenic plants offers a novel solution to pest infestations with reduced reliance on chemical pesticides.
Advancing research into the modes of action and environmental interactions of mycotoxins as biocontrol agents holds the promise of sustainable, long-term pest management solutions. This approach not only addresses the pressing need for effective pest control but also aligns with global efforts to reduce the environmental impact of agricultural practices, safeguarding both crop yields and ecosystem health.

In recent years, there has been a gradual shift in public perception about the indiscriminate use of pesticides. Therefore, there has been a search for safer plant protection interventions as a more eco-friendly alternative. The use of living agents or the formulation derived thereof is considered a safer option that is generally referred to as ‘biocontrol’. Alternaria is a widespread and ubiquitous genus of fungi that is known to have varied roles in the ecosystem. Different isolates of Alternaria belonging to different species have been identified to have the properties of a good biocontrol candidate in three parallel paradigms by various researchers. Their anticipated roles, viz., a potential weed control agent, a pest control agent, and/or plant disease control agent, have been identified and are under further investigation. Since Alternaria is associated with some important plant diseases, human allergens, and toxins, we should be conscious of their harmful side also before considering them as potential biocontrol candidates. Therefore, the present chapter, besides describing them as an effective biocontrol candidate, also cautions about their other ecological impacts, which should be assessed in detail before their commercialization at a widespread level. So, authors are presenting Alternaria as a ‘double-edged’ sword in terms of their biocontrol potential.

Plant diseases due to seed and soil-borne pathogens are major obstacles to sustainable crop production. Therefore, plant health is crucial to ensuring food security. The use of chemicals degrades plant health and has negative environmental effects. For the establishment of healthy and superior seedlings, especially in transplanted solanaceous vegetable crops, rapid and consistent seed emergence is crucial. Among the various techniques for controlling diseases that are transmitted through seeds and soil, seed biopriming is an environmentally benign, cost-effective, and simple seed treatment method. The practice of “biopriming” is treating seeds with advantageous microbial inoculants while maintaining regulated hydration levels to prevent radicle emergence. A major obstacle to sustainable agricultural production is plant diseases brought on by soil-borne and seed-borne pathogens. Seed biopriming entails soaking seeds in liquid suspensions of bioagents for a particular period of time, which initiates the physiological and developmental processes like DNA/RNA synthesis, protein accumulation, DNA repair, etc., within the seeds, thereby preventing radicle emergence before the seed is sown. Stronger membrane integrity, antipathogenic effects, lipid peroxidation counteraction, cellular and enzymatic repair systems, and metabolic elimination of harmful compounds from the primed seed are all benefits of seed biopriming. Thus, seed biopriming has given farmers a new biocontrol weapon for agricultural sustainability. Seed priming is a straightforward and affordable technique that gets seeds ready for impending pathogen-related difficulties.

Agrochemicals play an essential role in modern agriculture by managing pests and diseases and enhancing crop productivity. However, their widespread and often indiscriminate use has led to significant environmental concerns, such as water pollution, soil degradation, and adverse impacts on unintended organisms. As the need for sustainable agriculture is being increasingly realized, stability between crop production and minimizing the environmental impact of agrochemicals by increasing the use of biocontrol agents is necessary. The current chapter seeks to explore various types of agrochemicals, their benefits, and the environmental risks associated with their usage. It also delves into the concept of sustainable agriculture, which aims to meet the current food demands while ensuring the well-being of ecosystems and the accessibility of comparable resources for future generations. The current agricultural practices and proposed alternative strategies to reduce the environmental footprint of agrochemicals are also discussed. The possible solutions include integrated pest management, precision agriculture, organic farming practices, and the adoption of environmentfriendly biopesticides. The importance of the involvement of all the stakeholders, i.e., farmers, policymakers, and consumers, as well as the importance of sustainable agriculture and responsible use of agrochemicals, is also emphasized. The present chapter also highlights the significance of inter-disciplinary collaboration among researchers, agronomists, ecologists, and policymakers to address the complex challenges the overuse of agrochemicals pose to our goals for sustainable agriculture. Therefore, the adoption of sustainable agricultural practices is essential to increase food production to minimize the negative impacts of agrochemicals on the environment, ensuring more secure and resilient agriculture.