Bioscience Methods 2026, Vol.17, No.1, 1-8 http://bioscipublisher.com/index.php/bm 2 2 Types of Biocontrol Agents in Potato Pest Management 2.1 Microbial biocontrol agents Microbial biocontrol agents are microorganisms such as bacteria, fungi, and oomycetes that can suppress or inhibit the growth of potato pathogens. These agents work through various mechanisms, including the production of antimicrobial compounds, competition for nutrients and space, and induction of plant resistance. Bacillus subtilis strains have shown significant potential in controlling potato pathogens. For instance, Bacillus subtilis EG21 has demonstrated strong antagonistic effects against Phytophthora infestans and Rhizoctonia solani through the production of cyclic lipopeptides and extracellular enzymes like cellulase, pectinase, and chitinase. Similarly, Bacillus velezensis K-9 has been effective in managing potato scab caused by Streptomyces scabies, reducing disease symptoms and increasing potato yield (Ma et al., 2023). Lactic acid bacteria (LAB) such as Lactiplantibacillus plantarum KB2 LAB 03 have also been identified as effective biocontrol agents. This strain has shown a significant reduction in the infestation of multiple potato pathogens, including Pectobacterium carotovorum and Rhizoctonia solani, by producing organic acids and other antimicrobial metabolites (Steglińska et al., 2022). Arbuscular mycorrhizal fungi (AMF) and endophytic fungi like Epicoccum nigrumASU11 have been used to control blackleg disease caused by Pectobacterium carotovora. These fungi enhance plant growth and induce systemic resistance, reducing disease severity and improving potato yield (Bagy et al., 2019). 2.2 Natural predators and parasitoids Natural predators and parasitoids are another group of biocontrol agents that can help manage potato pests. These organisms prey on or parasitize pest species, thereby reducing their populations and the damage they cause to potato crops. Various insects and mites can serve as biological control agents. For example, lady beetles (Coccinellidae) and lacewings (Chrysopidae) are known to prey on aphids, which are common pests in potato fields (Volynchikova and Kim, 2022). Similarly, parasitoid wasps can target and parasitize the larvae of potato tuber moths, reducing their impact on potato crops. 3 Mechanisms of Action of Biocontrol Agents 3.1 Antagonism and competition Biocontrol agents (BCAs) often employ antagonism and competition to suppress potato pests and diseases. This involves the production of antimicrobial compounds, competition for nutrients and space, and direct parasitism of pathogens. For instance, Bacillus subtilis EG21 produces cyclic lipopeptides such as surfactins, which exhibit strong anti-oomycete and zoosporecidal effects against Phytophthora infestans. Rhizosphere bacteria isolated from resistant potato plants, including Streptomyces and Pseudomonas species, have shown significant inhibitory effects on the mycelium growth of P. infestans through the production of cellulase and catalase (Feng et al., 2021). These mechanisms highlight the potential of BCAs to outcompete and directly antagonize pathogens, thereby reducing disease incidence. 3.2 Induction of host plant resistance 3.2.1 Activation of systemic acquired resistance (SAR) in potato plants Systemic acquired resistance (SAR) is a plant defense mechanism that is activated in response to pathogen attack, leading to enhanced resistance throughout the plant. The co-treatment of potato plants with Bacillus thuringiensis B-5351 and salicylic acid (SA) has been shown to significantly increase the transcriptional activity of SAR-related genes such as PR1 and PAL, which are crucial for the plant's defense against P. infestans (Sorokan et al., 2021). This combined treatment not only enhances the plant's resistance to late blight but also increases the population of beneficial bacteria within the plant tissues, further contributing to disease suppression. 3.2.2 Enhancement of the plant’s immune response Biocontrol agents can also enhance the plant's immune response through the induction of induced systemic resistance (ISR) and mycorrhizal-induced resistance (MIR). For example, the dual inoculation of potato plants
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