Biological control in mulberry pest management: Innovations for sustainable sericulture

Introduction

Biological control of pests and diseases has emerged as a highly effective practice in modern agriculture. Advances in scientific pest management technologies have opened new opportunities for developing alternatives to synthetic pesticides in sericulture. This progress has created the right conditions to explore innovative growth-promoting methods and biological control strategies, including the use of commercial products, for the effective management of harmful insects in mulberry cultivation. In sericulture, a diverse range of pests threaten mulberry crops, including both insect and noninsect species, as well as parasites such as fungi, mites, and other insects. Since mulberry (Morus spp.) is the sole host plant for silkworms (Bombyx mori L.), any damage to its foliage directly impacts silk production. The main pests affecting mulberry include aphids, scales, borers, mosquitoes, mealybugs, dipterous larvae, and certain lepidopteran species. Infestations reduce both the quality and quantity of leaf yield, lowering productivity in sericulture. Chemical pesticides have traditionally been the primary control measure against these pests. While their application can temporarily boost crop production, repeated use often results in pesticide resistance. Broad-spectrum pesticides also have unintended consequences: they can harm beneficial fauna, disrupt soil microorganisms, and contaminate air, water, and soil. Their residues may persist in the environment, posing risks to human health and biodiversity. In addition, pesticide drift during aerial spraying can expose humans and non-target organisms to toxic chemicals. Reducing the negative effects of prolonged pesticide use requires a shift toward alternative pest control methods. Non-chemical approaches-such as mechanical methods, botanical extracts, and biological control-are being increasingly explored worldwide. Biopesticides derived from plants, including neem (Azadirachta indica) oil and kernel extracts, tobacco (Nicotiana tabacum) preparations, Mexican marigold (Tagetes patula) extracts, and gliricidia extracts, have shown promise. Other options include inorganic contact poisons such as magnesium fluoride and potassium silicofluoride. These alternatives, along with biocontrol agents, have been applied successfully against pests like the pink mealybug. Mulberry is not only crucial for silkworm rearing but also valued for its medicinal uses, fruit production, and ornamental appeal. However, like all cultivated crops, it is vulnerable to a range of pests and diseases-fungal, bacterial, and viral-that can cause severe economic losses. Heavy dependence on chemical control for these threats has led to pollution, harm to non-target organisms, and the growing problem of pest resistance. This has fueled interest in sustainable farming methods that minimize chemical inputs and emphasize environmental conservation. Biological control agents-living organisms or products derived from them-offer a practical and eco-friendly alternative to synthetic pesticides. They work by regulating pest populations naturally, thus maintaining ecological balance. The three primary categories of bio-control agents are predators, parasitoids, and pathogens. Predators feed directly on pests, parasitoids lay eggs in or on pest hosts so that the developing larvae consume them, and pathogens infect and kill pests, often targeting specific species or life stages. While biological control offers many benefits, its successful application in mulberry farming requires careful consideration. Many bio-control agents are species-specific, meaning they cannot eliminate all pest problems on their own. Their effectiveness can also be influenced by environmental factors such as temperature and humidity, necessitating precise timing and environmental management. Integrating bio-control agents with other pest control strategies-such as cultural and physical methods-requires thorough planning and coordination. Research and technological advancements continue to improve the potential of bio-control agents. Genetic improvements, advanced formulations, and detailed ecological studies of both pests and their natural enemies are expected to enhance their effectiveness. As these innovations progress, bio-control is likely to play an increasingly significant role in integrated pest management (IPM) for mulberry cultivation, contributing to sustainable and environmentally responsible sericulture.

Understanding bio-control agents

Biological control agents are living organisms employed to suppress pest and disease populations through natural ecological interactions. They play an important role in sustainable agriculture by reducing the need for chemical pesticides and maintaining environmental balance. In general, bio-control agents fall into three main categories: predators, parasitoids, and pathogens. These groups include a variety of organisms such as beneficial insects, spiders, nematodes, fungi, and other microorganisms that naturally regulate pest numbers.

Predators

Predators are organisms that feed directly on pests rather than on plants or other food sources. They actively capture and consume their prey, thereby limiting pest populations in agricultural systems. In mulberry cultivation, common predatory bio-control agents include lady beetles (Coccinellidae), lacewings (Chrysopidae), and spiders. These predators feed on soft-bodied insects such as aphids, mealybugs, and other small arthropods that damage mulberry leaves. Their presence in the field can significantly reduce pest numbers without harming the crop.

Parasitoids

Parasitoids are insects whose immature stages develop inside or on the body of a host insect, ultimately killing it. Adult parasitoids typically lay their eggs either within or upon the pest, and the developing larvae consume the host's tissues until it dies. In mulberry pest management, tiny wasps from families such as Braconidae and Trichogrammatidae are often used. These wasps exhibit high host specificity, targeting only certain pest species while leaving beneficial insects unharmed.

Pathogens

Pathogens include microorganisms such as bacteria, fungi, viruses, and certain nematodes that infect and kill pest species. These bio-control agents can cause diseases in pests, leading to a decline in their population. Some pathogens work by invading the pest's hemolymph (insect blood) and disrupting cellular functions, in some cases inducing apoptosis in insect hemocytes. Others infect the fat body tissues, releasing spores that multiply and further suppress the pest's immune response. For example, Bacillus thuringiensis (Bt) produces toxic spores that, once ingested, damage the insect gut, allowing the infection to spread and eventually killing the host. The effectiveness of pathogens lies in their ability to multiply within the pest population, providing sustained control over time. Unlike certain parasitoids that may have a narrow host range, many pathogens can infect a broader range of pest species, making them particularly useful in diverse tropical cropping systems. However, for optimal use, it is important to study their infection pathways, potential environmental constraints, and the possibility of pests developing protective immune responses. By understanding the biology, behavior, and ecological requirements of predators, parasitoids, and pathogens, farmers and researchers can design integrated pest management strategies that maximize the benefits of biological control while minimizing risks to non-target organisms.

Key bio-control agents used in mulberry plantation

Biological control in mulberry cultivation relies on a range of natural enemies that target different stages of pest development. These agents are generally classified into three groupspredators, parasitoids, and pathogens-each playing a unique role in integrated pest management (IPM).

Predators Lady Beetles (Coccinellidae)

Lady beetles are among the most efficient predators of softbodied arthropods such as aphids, scale insects, and mealybugs. Their aggressive feeding behavior helps maintain pest populations at low levels throughout the growing season. Both adult and larval stages of lady beetles actively consume large numbers of pests, making them highly valuable in mulberry plantations.

Lacewings (Chrysopidae)

Lacewing larvae, often referred to as "aphid lions," are voracious feeders on aphids, whiteflies, thrips, and other small insects. They are particularly effective during pest outbreaks, as they can drastically reduce pest numbers in a short period. By targeting multiple pest species, lacewings contribute significantly to the overall health and productivity of mulberry crops.

Spiders

Various spider species, including orb-weavers and jumping spiders, are generalist predators that feed on a wide range of insect pests. They help control pest populations by trapping or ambushing their prey, thus reducing the need for chemical interventions. Their presence in mulberry fields supports the ecological balance by suppressing multiple pest types simultaneously.

Parasitoids Trichogramma Wasps (Trichogrammatidae)

Trichogramma species are tiny egg parasitoids that target the eggs of moths and butterflies, including species harmful to mulberry crops. By attacking pests at the egg stage, these wasps prevent the emergence of destructive larvae, offering an early and effective form of pest control. Their preventive action is particularly valuable in avoiding severe infestations.

Braconid Wasps (Braconidae)

Braconid wasps parasitize the larval stages of pests such as caterpillars and borers. They lay their eggs inside or on the pest larvae, and the developing parasitoid consumes the host from within. This targeted control is especially effective against mulberry borers, which can cause significant damage if left unmanaged.

Pathogens Bacillus thuringiensis (Bt)

Bacillus thuringiensis is a naturally occurring soil bacterium that produces toxins lethal to caterpillars and certain insect larvae. Bt formulations are widely used in organic mulberry farming to control pests like borers. The bacteria act by disrupting the pest's digestive system, leading to death within a few days of ingestion.

Beauveria bassiana

This entomopathogenic fungus infects and kills various insect pests, including whiteflies and spider mites. It invades the host through the cuticle, proliferates inside the body, and eventually causes death. In mulberry cultivation, B. bassiana is applied as a biological pesticide, reducing pest populations without harming beneficial insects.

Metarhizium anisopliae

Another important entomopathogenic fungus, Metarhizium anisopliae, is effective against soil-dwelling pests such as beetles and other ground-feeding insects. It infects the host upon contact, penetrating the exoskeleton and multiplying inside the insect's body. This makes it particularly useful for managing pests that damage mulberry roots and lower stems.

Effective strategies for implementing bio-control agents

The use of bio-control agents is most effective when incorporated into a broader integrated pest management (IPM) framework. These agents should not be seen as standalone measures but as part of a well-coordinated pest management system. For maximum success, several strategies must be followed.

Selection of Appropriate Bio-Control Agents

The efficiency of bio-control depends largely on selecting the correct agent for the target pest and prevailing environmental conditions. The selection process should be based on accurate pest identification, knowledge of the pest's life cycle, and the mode of action of the bio-control agent. For example, Trichogramma species are ideal for controlling moth and butterfly pests because they parasitize the egg stage, preventing larval damage. Lady beetles (Coccinellidae) are effective against aphids and scale insects, while entomopathogenic fungi such as Beauveria bassiana target a wide range of insect pests. Similarly, Bacillus thuringiensis (Bt) is particularly useful for managing caterpillar infestations.

Timing and Application Methods

The success of biological control also depends on the correct timing and method of application. "Sensitive timing"introducing the control agent at the most vulnerable stage of the pest's life cycle-is critical. For instance, Trichogramma wasps should be released when adult moths are laying eggs to ensure the parasitoids can target them before they hatch. Application techniques must ensure thorough coverage of affected areas and promote the movement and establishment of bio-control agents throughout the crop. In some cases, this may involve localized release, slow dispersal methods, or repeated introductions to sustain pest suppression.

Monitoring and Evaluation

Continuous monitoring is essential to evaluate the effectiveness of bio-control agents. Regular surveys of pest and natural enemy populations help determine whether the agents are successfully establishing and reducing pest numbers. If results are insufficient, adjustments can be made-such as increasing release frequency or modifying application methods. Data from monitoring programs also provide valuable feedback for refining bio-control strategies over time.

Benefits of Using Bio-Control Agents

Biological pest control in mulberry cultivation offers several advantages over conventional chemical interventions. Many biocontrol agents, including bacteria, fungi, viruses, protozoa, and beneficial nematodes, operate through multiple modes of action, making them versatile and sustainable pest management tools.

Residue-Free Production

Unlike chemical pesticides, bio-control agents leave minimal or no residues on crops or in the environment. Many beneficial microorganisms degrade quickly under natural environmental conditions, reducing the risk of long-term contamination.

Environmental Protection

By reducing the reliance on synthetic chemicals, bio-control minimizes pesticide residues in food, prevents water and soil pollution, and helps protect beneficial organisms.

Sustainability

Bio-control supports natural pest regulation, maintains biodiversity, and is far less likely to contribute to pest resistance compared to chemical methods.

Human and Wildlife Safety

These agents are generally biodegradable and have low toxicity to humans, pollinators, and other non-target species, making them a safer choice for pest control.

Cost-Effectiveness

Although initial setup costs may be higher, bio-control can be more economical in the long term. Once established, natural enemies can provide ongoing pest suppression, reducing the need for repeated chemical applications and associated expenses.

Resistance Management

By diversifying pest control methods and reducing the overuse of chemicals, bio-control agents lower the risk of pests developing resistance, thereby enhancing the long-term effectiveness of pest management strategies.

Conclusion

Biological control agents represent a cornerstone in the sustainable management of pests and diseases in mulberry cultivation. Their value lies not only in their ability to effectively suppress harmful pest populations but also in their capacity to do so while maintaining ecological balance, safeguarding farmer health, and reducing the environmental footprint of pest management practices. By harnessing the natural roles of predators, parasitoids, and microbial pathogens, farmers can protect mulberry crops without relying heavily on synthetic pesticides, which often lead to soil and water contamination, pesticide resistance, and harmful residues on foliage. The integration of bio-control agents into a comprehensive Integrated Pest Management (IPM) framework ensures that pest control is proactive, targeted, and long-lasting. Scientific advancements are continuously improving the efficiency, specificity, and adaptability of these agents, making them even more practical for modern agriculture. In mulberry farmingparticularly for sericulture-this approach ensures healthier plants, improved yields, and reduced production costs over time. As global demand for mulberry-based rises, the importance of resilient, high-yielding crops becomes increasingly clear. Bio-control strategies, by replacing or reducing chemical interventions, not only safeguard the longterm productivity of mulberry plantations but also align with global movements toward environmentally responsible agriculture. By promoting crop health, enhancing biodiversity, and supporting farmer livelihoods, bio-control agents serve as a strategic, sustainable, and economically viable alternative that will continue to play a pivotal role in the future of mulberry cultivation.

Future prospects and research directions

Looking ahead, the future of biological control in mulberry cultivation lies in harnessing cutting-edge molecular biology, genetics, and biotechnology to improve the efficiency, specificity, and adaptability of bio-control agents (BCAs). The development of user-friendly technologies for isolating, massproducing, and enhancing the performance of bio-priming agents and biopesticides will be essential for their widespread adoption. One promising avenue is the exploration of novel microbial isolates and their bioactive metabolites from diverse environments. These could provide new tools for controlling multiple pest species that threaten mulberry fields. Such research would not only expand the library of available BCAs but also lead to the discovery of compounds with unique modes of action, reducing the risk of resistance development in pest populations. The integrated application of bio-priming agents with other bioinputs is expected to become a mainstream strategy in pest management. This approach has the potential to offer broadspectrum pest suppression while maintaining ecological safety, making it an innovation with high commercial and environmental value. From a scientific standpoint, deeper biochemical and molecular investigations are needed to understand the genetic and transcriptional regulatory pathways triggered by BCA-derived compounds, especially those linked to plant defense systems. For example, research could focus on evaluating the effectiveness of BCAs when applied to mulberry leaves at various concentrations, such as identifying the minimum effective dose in the range of 2-10 mg/mL compared to the standard 100 mg/mL. Additionally, studies on Bacillus thuringiensis (Bt) formulations derived from different Aspergillus isolates-and their effectiveness against various Aspergillus flavus strains-could provide valuable insights. Future work should also emphasize comparative performance studies between different BCAs, moving beyond a narrow focus on A. flavus or mulberry fruits to include other economically significant pests and crop systems. Such comprehensive evaluations will help in identifying the most robust, costeffective, and environmentally compatible solutions, ultimately ensuring that mulberry cultivation remains sustainable, productive, and resilient in the face of evolving pest pressures.

References

1. Baruah JP, Kalita C. Integrated pest management of uzi fly (Exorista sorbillans) in Muga silkworm Antheraea assamensis Helfer (Lepidoptera: Saturniidae): A review. J Entomol Zool Stud. 2020;8(4):341-343.
2. Bawaskar DM, Chowdary NB, Kedar SC, Reddy BT, Selvaraj C, Rathore MS, et al. Traditional and innovative technologies for pest management of tropical tasar silkworm, Antheraea mylitta (Drury) by the tribes of Eastern-Central India. Int J Trop Insect Sci. 2022;42(2):1737-1748.
3. Saini P, Rohela GK, Kumar JS, Shabnam AA, Kumar A. Cultivation, utilization, and economic benefits of Mulberry. In: The Mulberry Genome. Cham: Springer; 2023. p.13-56.
4. Dandin SB, Kumari V. Mulberry (Morus sp.) cultivation for sustainable sericulture. CRC Press; 2021. p.188-207.
5. Gupta SK, Mukhopadhay SK, Bhattacharyya H, Modak BK. Integrated management of diseases and pests of silkworm. J Environ Sociobiol. 2016;13(2):147-155.
6. Elango K, Sobhana E, Sujithra P, Bharath D, Ahuja A. Traditional agricultural practices as a tool for management of insects and nematode pests of crops: An overview. J Entomol Zool Stud. 2020;8(3):237-245.
7. Koshariya AK, Jadhav SM. Organic farming and integrated nutrient management (INM) in horticulture. In: Microbial Flocculants as an Alternate to Chemical Flocculants for Wastewater Treatment. 2021. p.49.
8. Bharathi KM, Susikaran BS, Parthiban KT, Murugesh KA, Chozhan K. The economics of commercial mulberry saplings production using mini clonal technology over conventional method. Pharma Innov J. 2022;11:1236-1241.
9. Bindroo BB. Breakthroughs and betterments in silkworm improvement. In: Beneficial Insect Farming -Benefits and Livelihood Generation. 2016. p.163.
10. Bharathi KM, Susikaran S, Parthiban KT. A comparative biochemical study of mulberry (Morus spp.) mini clones over conventional stem cuttings. Int J Plant Soil Sci. 2024;36:975-983.
11. Bharathi KM, Susikaran S, Parthiban KT, Vasanth V, Vijay S. Influence of different transplanting days on yield attributes of mini clones under field conditions for Morus indica (V1). Madras Agric J. 2023;111:1-3.
12. Madyarov SR. Biotechnological approaches in sericultural science and technology of Uzbekistan. Int J Ind Entomol. 2005;11(1):13-19.
13. Singh RN, Maheshwari M, Saratchandra B. Sampling, surveillance and forecasting of insect population for integrated pest management in sericulture. Int J Ind Entomol. 2004;8(1):17-26.
14. Poveda J. Trichoderma as bio-control agent against pests: New uses for a mycoparasite. Biol Control. 2021;159:104634.
15. Singh RN, Saratchandra B. Biological control strategy of uzi fly in sericulture. Int J Ind Entomol. 2003;6(2):125-132.
16. Sakthivel N, Kumaresan P, Qadri SM, Ravikumar J, Balakrishna R. Adoption of integrated pest management practices in sericulture: A case study in Tamil Nadu. J Biopestic. 2012;5:212.
17. Unni BG, Devi B, Kakoty Y, Wann SB, Borah A, Dowarah P. Role of plant-microbe interactions in the sustainable development of Muga sericulture. In: Bacteria in Agrobiology: Plant Probiotics. 2012. p.213-225.
18. Singh A, Bhardwaj R, Singh IK. Bio-control agents: Potential of biopesticides for integrated pest management. In: Biofertilizers for Sustainable Agriculture and Environment. 2019. p. 413-433.
19. Rahman S, Biswas SK, Barman NC, Ferdous T. Plant extract as selective pesticide for integrated pest management. Biotechnol Res. 2016;2(1):6-10.
20. Singh A, Kumar V, Majumdar M, Guha L, Neog K. A comprehensive review of insect pest management in Muga silkworm (Antheraea assamensis Helfer): Current scenario and future prospects. J Exp Agric Int. 2024;46(5):47-55.
21. Van Zyl C, Malan AP. Role of entomopathogenic nematodes as biological control agents of insect pests, with emphasis on mass culturing and in vivo production. Afr Entomol. 2014;22(2):235-249.
22. Singh RN, Maheshwari M, Saratchandra B. Biocoenology and control of whiteflies in sericulture. Insect Sci. 2005;12(6):401-412.
23. Singh S, Singh A, Kumar S, Mittal P, Singh IK. Protease inhibitors: Recent advancement in its usage as a potential bio-control agent for insect pest management. Insect Sci. 2020;27(2):186-201.
24. El-Wakeil N, Saleh M, Abu-Hashim M. Cottage industry of biocontrol agents and their applications. 2020.
25. Singh D, Raina TK, Singh J. Entomopathogenic fungi: An effective biocontrol agent for management of insect populations naturally. J Pharm Sci Res. 2017;9(6):833-840.
26. Singh RN, Rao JK, Sampson MV. Role of parasitoids in pest management in Tasar culture. In: Biocontrol Potential and Its Exploitation in Sustainable Agriculture. Boston: Springer; 2001. p.379-387.
27. Liu SS, Rao A, Vinson SB. Biological control in China: Past, present, and future. Biol Control. 2014;68(1):5-7.
28. Ballal CR. Biological control for sustainable plant protection. Ensuring Food Safety, Security and Sustainability through Crop Protection. 2021;5:20-26.
29. Nadaf HA, Vishaka GV, Sathyanarayana K, Chandrashekharaiah M, Rathore MS, Chowdary NB, et al. Integrated farming system: A key to sustainable livelihood in Tasar sericulture. J Exp Zool India. 2022;25(2).
30. Bhat A, Fatima A, Dar KA. Biocontrol and its role in sericulture: A review paper. Int J Adv Res Sci Eng. 2018;7:1881-1885.
31. Singh RN, Saratchandra B. An integrated approach in the pest management in sericulture. Int J Ind Entomol. 2002;5(2):141-151.
32. Cappellozza S, Casartelli M, Sandrelli F, Saviane A, Tettamanti G. Silkworm and silk: Traditional and innovative applications. Insects. 2022;13(11):1016.
33. St. Leger RJ, Wang C. Genetic engineering of fungal biocontrol agents to achieve greater efficacy against insect pests. Appl Microbiol Biotechnol. 2010;85:901-907.
34. Sujatha GS, Kumar GA, Teja KS, Devi DL, Panda A, Rupali JS, et al. A comprehensive review of the effect and mitigation of climate change on sericulture. Int J Environ Clim Change. 2024;14(7):776-788.
35. Sabbahi R, Hock V, Azzaoui K, Saoiabi S, Hammouti B. Global perspective of entomopathogens as microbial biocontrol agents of insect pests. J Agric Food Res. 2022;10:100376.
36. Singh RN, Maheshwari M. Biological control of pests of non-mulberry silkworms and its host plants in India. Int J Ind Entomol. 2002;4(2):83-91.
37. Sharma K, Kapoor B. Sericulture as a profit-based industry: A review. Indian J Pure Appl Biosci. 2020;8(4):550-562.
38. Wani MY, Mir MR, Baqual MF, Mehraj K, Bhat TA, Rani S. Role of foliar sprays in sericulture industry. J Pharmacogn Phytochem. 2017;6(4):1803-1806.