Effective Biological Control Research Articles

The Effect of Climate Change on Indicator Wetland Insects: Predicting the Current and Future Distribution of Two Giant Water Bugs (Hemiptera: Belostomatidae) in South Korea.

Giant water bugs (Hemiptera: Belostomatidae) are top predators in wetland ecosystems, serving as biological indicators of the health of lentic ecosystems and as effective biological control agents for freshwater snails and mosquitoes. This study aimed to predict the current and future distribution of two Korean giant water bugs, Appasus japonicus and Diplonychus esakii, under three climate change scenarios, contributing to the sustainable management of wetland ecosystems in South Korea. Using MaxEnt models, we employed seven climatic and three non-climatic variables to investigate the habitat preferences and distribution patterns of the species. The results revealed that A. japonicus is likely to experience a northward range contraction due to climate change, while D. esakii is predicted to expand its distribution northward without losing its current range. These responses may lead to occupancy turnover between the two species, potentially driving reassembly in aquatic organism community. Elevation was the primary factor influencing the distribution of A. japonicus, whereas annual mean temperature was the most informative variable for D. esakii, both factors derived under the current climate conditions. These findings suggest that both species are highly sensitive to climate change, with potential range shifts toward higher latitudes and elevations. This study provides insights into how climate change could impact two giant water bugs, thereby supporting future efforts to manage and conserve wetland ecosystems in this country.

Modeling the effects of trap crop attraction strength, patch dispersion, and biological control on pest suppression

Modeling the effects of trap crop attraction strength, patch dispersion, and biological control on pest suppression

Isolation, characterization, and application of a novel Pseudomonas fluorescens phage vB_PF_Y1-MI in contaminated milk.

The food industry has incurred substantial losses from contamination by Pseudomonas fluorescens, emphasizing the critical importance of implementing effective control strategies. Phages are potential sterilizers due to their specific killing abilities and the difficulty bacteria face in developing resistance. However, a significant barrier to their development is the lack of diversity among phage types. In this study, we characterized a novel lytic P. fluorescens phage, named vB_PF_Y1-MI. Phage vB_PF_Y1-MI displayed a latent period of nearly 10min and a high burst size of 1493 PFU/cell. This phage showed good activity over a wide range of temperature (up to 70°C) and pH (3-12). The genome of phage vB_PF_Y1-MI spans 93,233bp with a GC content of 45%. It encompasses 174 open-reading frames and 19 tRNA genes, while no lysogeny or virulence-associated genes were detected. Phylogenetic analysis positions it as a novel unassigned evolutionary lineage within the Caudoviricetes class among related dsDNA phages. Our study provides foundational insights into vB_PF_Y1-MI and emphasizes its potential as an effective biological control agent against P. fluorescens. This research offers crucial theoretical groundwork and technical support for subsequent efforts in preventing and controlling P. fluorescens contamination.

Research on the multitarget 3D trajectory tracking method of Thalassodes immissaria in the thermal infrared region based on YOLOX-GMM and SORT-Pest.

Studying the behavioral responses and movement trajectories of insects under different stimuli is crucial for developing more effective biological control measures. Therefore, accurately obtaining the movement trajectories and behavioral parameters of insects in three-dimensional space is essential. This study used the litchi pest Thalassodes immissaria as the research object. A special binocular vision observation system was designed for nighttime movement. A thermal infrared camera was used for video recording of T. immissaria in a lightless environment. Moreover, a multi-object tracking method based on the YOLOX-GMM and SORT-Pest algorithms was proposed for tracking T. immissaria in thermal infrared images. By obtaining the central coordinates of the two T. immissaria in the video, target matching and 3D trajectory reconstruction in the parallel binocular system were achieved. Error analysis of the T. immissaria detection and tracking model, as well as the 3D reconstruction model, showed that the average accuracy of T. immissaria detection reached 89.6%, tracking accuracy was 96.9%, and the average error of the reconstructed 3D spatial coordinates was 15 mm. These results indicate that the method can accurately obtain the 3D trajectory and motion parameters of T. immissaria. Such data can greatly contribute to researchers' comprehensive understanding of insect behavioral patterns and habits, providing important support for more targeted control strategies.

Insecticidal effect of two Turkish entomopathogenic nematode isolates against Tribolium castaneum (Herbst) larvae and adults at different conditions

Red flour beetle, Tribolium castaneum (Herbst.), is the most common pest of stored grains and products. Aerial and contact pesticides are used to control this pest. However, the red flour beetle has also developed significant resistance to phosphine, the main fumigant currently in use worldwide. The adverse effects of pesticides on non-target organisms, groundwater contamination, residues on food crops, and the emergence of insect resistance to chemicals have compelled the industry to prioritize the development of alternative control measures. Entomopathogenic nematodes find application in various agricultural systems. The insecticidal effect of two isolates of Steinernema feltiae Filipjev (Nematoda: Steinernematidae) and Heterorhabditis bacteriophora Poinar (Nematoda: Heterorhabditidae) against the different stages of T. castaneum. The entomopathogenic nematode isolates were examined at four concentrations (0, 250, 500, and 1000 IJs/ml) with a distilled water at 15 and 25 ± 1 °C temperatures. Results revealed that both S. feltiae (A-16) caused with 92.33% mortality rate while H. bacteriophora (O-7) caused with 76.77% mortality in the last instar larvae of the red flour beetle while these two species caused 75.38% and 66.85% mortality in adults, at 25 °C. The effect of nematodes decreased as the temperature decreased. According to results, the mortality rate of T. castaneum larvae treated with S. feltiae (A-16) with (54.62%) was significantly higher than that of H. bacteriophora (O-7) with (32.13%) 96 h after inoculation at 15 °C. The data indicated that 1000 IJs/ml was the most effective concentration of tested EPN isolates for all larval and adult stages.In this study, our findings indicate that S. feltiae (A-16) and H. bacteriophora (O-7) can be used as effective biological control agents against both the larval and adult stages of the red flour beetle. The results demonstrate that EPNs are promising candidates for biocontrol of T. castaneum. This information is useful in designing future biological control programs.

Biological and population parameters of Telenomus remus and Trichogramma atopovirilia as biological control agents for Spodoptera frugiperda

Maize production faces a significant threat from Spodoptera frugiperda (J. E. Smith) worldwide; historically, Trichogramma pretiosum Riley has served as the primary augmentative egg parasitoid for its biological control. However, since 2004, Telenomus remus Nixon has emerged as a viable global alternative. On a regional scale, in Mexico, Trichogramma atopovirilia (Oatman & Platner) was theorized to outperform T. pretiosum, proving superior in both laboratory and field conditions in 2020. To further the field efficacy of the augmentative use of parasitoids as biological agents of S. frugiperda, we conducted comparisons of biological and population parameters under laboratory-controlled conditions to determine whether T. remus would be more effective than T. atopovirilia, the best Trichogramma parasitoid in Mexico for S. frugiperda. We found that the former parasitoid had statistically significant longer female and male longevity, as well as a higher proportion of female offspring, and greater numerical values in net reproduction rate, intrinsic rate of increase, and finite rate of increase, but no differences were found in the number of days required for both parasitoids to develop from egg to female or egg to male, as well as in the mean generation time and doubling time. Under the conditions of these trials, T. remus had a 47.02% greater intrinsic rate of increase (rm) and may thus be a more effective biological control agent for S. frugiperda than T. atopovirilia. However, these biological and population parameter comparisons are the first execution worldwide; further studies are needed to validate these promising T. remus results.

Role of eggplant trichome in whitefly oviposition and its relevance to biological control under greenhouse conditions.

The combined release of the predatory mite Amblyseius swirskii (Athias-Henriot) and the mirid Nesidiocoris tenuis (Reuter) provides effective biological control of the tobacco whitefly (Bemisia tabaci (Gennadius)) in greenhouse eggplant. However, knowing how plants' trichomes affect pest-predator interactions could improve whitefly management. Here, the effect of two varieties with either the presence or absence of trichomes was assessed on naturally occurring whitefly populations and predator abundance in a first experiment under field conditions. Predator-prey models were developed to assess the effect of trichomes on pest and predator population dynamics under field conditions. In a second semi-field experiment, the occurrence and oviposition preferences of B. tabaci and A. swirskii in the same eggplant varieties were compared. Significantly higher numbers of whitefly and mite, adults and eggs, were found on the hairy variety in both experiments. However, no differences were found in N. tenuis abundance between varieties under field conditions. Predator-prey models showed that whitefly growth rate increased in the hairy variety. N. tenuis and A. swirskii showed different fitness parameters according to the variety, with the former displaying better performance in the hairless variety and the latter in the hairy variety. Both predators effectively controlled the increase in whitefly populations in both varieties. Overall, the findings suggest that the hairless variety is more effective in deterring whiteflies. Additionally, the higher population of A. swirskii on the hairy variety indicates that this predator benefited from both the presence of trichomes and the prey.

Early life food intake modulates effects of diet restriction on lifespan and fecundity in later life in a predatory mite (Acari: Phytoseiidae)

Abstract The nutritional status of an individual can significantly influence its life history traits, including development, growth, reproduction, and survival. In the predatory mite Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae), the plasticity of life history traits, such as developmental time and size at maturity, is influenced by the quality and quantity of food. This study aimed to investigate the effects of dietary restriction at different life stages (i.e., juvenile, early adulthood, and later adulthood) on the lifespan and fecundity of P. persimilis. We found that reduced dietary intake during early adulthood resulted in a shorter lifespan for both male and female P. persimilis. Furthermore, this study demonstrated a sex-specific response to dietary restriction: it extended the lifespan of males but reduced that of females during later adulthood. Diet restriction during the postovipositional period of females showed the most variable life history trait response. Our results showed that the impact of diet restriction at different life stages can have combined influences on the postovipositional duration of P. persimilis, where the individuals receiving diet restriction during immature development and early adulthood had a greater reduction in ovipositional duration as those experiencing diet restriction during late adulthood. In addition, we observed a positive correlation between the lifespan and fecundity of females, with higher prey availability increasing both. The insights obtained from our research contribute to a better understanding of the aging process and dietary requirements of P. persimilis, which can facilitate the development of more effective biological control strategies using this predator for spider mites in agriculture.

Enhancing Pomegranate Yield Through Biological Control of Shot Hole Borer: A Comparative Studyy

This study demonstrates the potential of Beauveria bassiana, Metarhizium anisopliae, and Trichogramma spp. as effective biological control agents against the Shot Hole Borer in pomegranate orchards. The findings suggest that these bioagents can be integrated into existing pest management programs, offering a viable and environmentally sustainable alternative to chemical pesticides. This research contributes to the broader field of sustainable agriculture and highlights the importance of biological control in managing pest populations in fruit crops.

Non-chemical management of fungal diseases in berries: A review

Abstract Organically grown berries are highly valued for their significant economic and nutritional benefits, playing a crucial role in fostering sustainable agriculture. However, meeting the escalating demand for organic berries while sustaining profitable yields of top-quality produce remains challenging, primarily due to the obstacles presented by plant diseases and significant insect pests acting as vectors. Globally, significant losses in organic berry agriculture stem from pathogenic organisms such as bacteria, viruses, fungi, oomycetes, nematodes, and parasitic plants. Although chemical pesticides have historically served as effective control measures, their high costs and potential environmental and health risks necessitate exploring alternative approaches. Consequently, there have been groundbreaking advancements in biological methods for disease management, driven by an enhanced understanding of the intricate interactions between plant pathogens and the plant immune system. This comprehensive analysis elucidates the common pests and diseases affecting organic berry crops, with particular emphasis on fungal pathogens posing the greatest risk. The review documents efficient management strategies to mitigate the harm caused by fungal infections, focusing on biological control using antagonistic microorganisms. Thanks to years of intensive research, numerous commercially available products showcasing the effectiveness of biological control in combating pathogenic threats in organic berry crops have emerged. Furthermore, our review provides insights into recent advancements in the diagnosis and detection of plant diseases, encompassing both time-tested approaches from the previous generations and important methods currently in use. Ultimately, this review aims to help organic berry growers implement successful eco-friendly management strategies to safeguard their crops and boost yields by offering an overview of the latest developments in disease management.

Long-term post-release evaluation shows Hypogeococcus sp. is an effective biological control agent for queen of the night cactus in South Africa

ABSTRACT We conducted long-term monitoring of Hypogeococcus sp. (Pseudococcidae) as a biocontrol agent for queen of the night cactus (Cereus jamacaru De Candolle). The biocontrol agent was released at three sites representing the regions where the plant is problematic in South Africa, and both agent and plant populations were monitored over time. The proportion of plants producing fruits or flowers decreased by 36% each year, with all plants no longer flowering between two and seven years after release. Plant density reduced by 42% each year after release. Hypogeococcus sp. is an effective agent against C. jamacaru in South Africa.

Isolation of the Endophytic Fungus Aspergillus terreus from a Halophyte (Tetraena qatarensis) and Assessment of Its Potential in Tomato Seedling Protection.

Living in diverse environmentally harsh conditions, the plant exhibits a unique survival mechanism. As a result, the endophytes residing within the plant produce specific compounds that promote the plant's growth and defend it against pathogens. Plants and algae symbiotically harbor endophytes, i.e., microbes and microorganisms living within them. The objective of this study is to isolate endophytic fungi, specifically strains of Aspergillus terreus, from the leaves of the salt-tolerant plant Tetraena qatarensis and to explore the salt tolerance, antagonistic activity, and growth promotion properties. Strain C A. terreus (ON117337.1) was screened for salt tolerance and antagonistic effects. Regarding salt tolerance, the isolate demonstrated the ability to thrive in a concentration of up to 10% NaCl. A. terreus showed inhibitory activity against four fungal phytopathogens, namely Fusarium oxysporum, Alternaria alternata, Colletotrichum gloeosporioides, and Botrytis cinerea. The GC-MS investigation of the fungal (strain C Aspergillus terreus) extract showed the presence of about 66 compounds (secondary metabolites). Secondary metabolites (SMs) are produced, like Hexadecanoic acid, which aids in controlling phytopathogens. Also produced is lovastatin, which is used to treat hypercholesterolemia. Strain C, which showed salinity tolerance and the highest inhibitory activity, was further analyzed for its effect on tomato seed germination under pathogen stress from Fusarium oxysporum. The greenhouse experiment indicated that the fungi increased the length of tomato seedlings and the plant biomass. Therefore, the selected endophytes derived from Tetraena qatarensis were scrutinized for their potential as biocontrol agents, aiming to thwart fungal pathogens and stimulate plant growth. The in vitro and in vivo assessments of strain C (Aspergillus terreus) against Fusarium oxysporum in this investigation indicate the promising role of endophytes as effective biological control agents. Investigating novel bio-products offers a sustainable approach to agriculture, gradually reducing dependence on chemical fungicides.

Galling by Trichilogaster sp. suppresses the growth of Acacia auriculiformis saplings

Pre-release efficacy assessments (PREAs) are used in weed biological control to predict the potential impact of prospective agents. These assessments enable the most damaging agents to be prioritised for host testing and release. Further, the inclusion of this information in release applications enables regulators to consider the benefits of an agent alongside any risks. We conducted a PREA to evaluate the efficacy of Trichilogaster sp., a galling wasp that is being considered for release in Florida to control invasive earleaf acacia, Acacia auriculiformis. This species is multivoltine and primarily galls vegetative buds. We performed a glasshouse trial exposing A. auriculiformis saplings to one generation of the gall wasp to determine the effect of galling on plant performance. We monitored the growth parameters and development of exposed and unexposed saplings every three weeks for twelve weeks. Above-ground and below-ground biomass were measured at the completion of the trial. One generation of galling reduced sapling height by 37.44 % (±5.57), above-ground biomass by 32.19 % (±4.00), and below-ground biomass by 38.26 % (±7.47). Galling also significantly reduced the other key growth parameters of stem weight, leaf weight, total branch length, and the number of nodes, shoot tips, and leaves. This Trichilogaster species significantly damages juvenile A. auriculiformis plants and could be an effective classical biological control agent if released in Florida, especially if it is not limited by a specialist third trophic level.

A benefit-risk analysis for biological control introductions based on the protection of native biodiversity.

The release of biological control agents has been an important means of controlling invasive species for over 150 years. While these releases have led to the sustainable control of over 250 invasive pest and weed species worldwide, a minority have caused environmental harm. A growing recognition of the risks of biological control led to a focus on risk assessment beginning in the 1990s along with a precipitous decline in releases. While this new focus greatly improved the safety of biological control, it came at the cost of lost opportunities to solve environmental problems associated with invasive species. A framework that incorporates benefits and risks of biological control is thus needed to understand the net environmental effects of biological control releases. We introduce such a framework, using native biodiversity as the common currency for both benefits and risks. The model is based on interactions among four categories of organisms: (1) the biological control agent, (2) the invasive species (pest or weed) targeted by the agent, (3) one or more native species that stand to benefit from the control of the target species, and (4) one or more native species that are at risk of being harmed by the released biological control agent. Conservation values of the potentially benefited and harmed native species are incorporated as well, and they are weighted according to three axes: vulnerability to extinction, the ecosystem services provided, and cultural significance. Further, we incorporate the potential for indirect risks to native species, which we consider will result mainly from the ecological process of agent enrichment that may occur if the agent exploits but does not control the target pest or weed. We illustrate the use of this framework by retrospectively analyzing the release of the vedalia beetle, Novius (= Rodolia) cardinalis, to control the cottony cushion scale, Icerya purchasi, in the Galapagos Islands. While the framework is particularly adaptable to biological control releases in natural areas, it can also be used in managed settings, where biological control protects native species through the reduction of pesticide use.

Life cycle, host specificity and potential impact of a gall-inducing thrips Acaciothrips ebneri, a biological control agent for prickly acacia (Vachellia nilotica subsp. indica) in Australia

Prickly acacia (Vachellia nilotica subsp. indica (Benth.) Kyal. & Boatwr.; Fabales: Fabaceae) is a Weed of National Significance and a target for biological control in Australia. Currently there are no effective biological control agents for the weed in Australia. Based on genetic and climate matching, a gall thrips (Acaciothrips ebneri Karny; Thysanoptera: Phlaeothripidae) inducing rosette galls resulting in shoot tip dieback, was identified as a prospective biological control agent from Ethiopia. No-choice host-specificity tests were conducted on 59 test plant species in a high security quarantine in Brisbane, Australia. Acaciothrips ebneri is host-specific, inducing galls and reproducing only on prickly acacia. Acaciothrips ebneri, as predicted by the CLIMEX model, is suited to hot and arid western Queensland where major prickly acacia infestations occur. The Australian Government approved A. ebneri for field release in October 2022. This is the first time a true gall-inducing thrips has ever been approved as a weed biological control agent. Field releases commenced in January 2023 and are in progress. There are early signs of field establishment resulting in shoot tip die back in the field, and field release and monitoring will continue.

Intraguild species presence alters Aphidoletes aphidimyza (Diptera: Cecidomyiidae) and Aphidius gifuensis (Hymenoptera: Braconidae) foraging responses.

The predatory gall midge, Aphidoletes aphidimyza (Rondani), and tobacco aphid cocoon wasp, Aphidius gifuensis Ashmead, are important natural enemies of Myzus persicae (Sulzer) (Hemiptera: Aphididae). Predation by A. aphidimyza and A. gifuensis can regulate M. persicae; however, how interspecific interference competition affects their foraging efficiency is unknown. Here, we investigated the consumption and parasitization abilities of A. aphidimyza 3rd instar larva and A. gifuensis adults under various conditions. Consumption of parasitized aphids by A. aphidimyza 3rd instar larvae was significantly lower than that of nonparasitized controls, with a substantial increase in handling time. The presence of A. gifuensis adults did not significantly affect the predation capacity of A. aphidimyza larvae. Relative to controls, A. aphidimyza larvae predation trace (PT) and imago activity significantly decreased A. gifuensis parasitism rates at different aphid densities. Further, A. aphidimyza larvae PT increased the A. gifuensis handling time of M. persicae, whereas the presence of A. aphidimyza adults had the opposite effect. Coexistence with heterospecific natural enemies reduced the parasitic capacity of A. gifuensis, whereas A. aphidimyza larvae predation capability was influenced to a lesser extent. Our results demonstrate that intraguild interactions strongly influence the predatory and parasitic efficacy of A. aphidimyza and A. gifuensis, although the effect on A. gifuensis was more pronounced. For effective biological control of M. persicae using A. aphidimyza and A. gifuensis, we recommend releasing A. aphidimyza first to mitigate intraguild predation and enhance the overall success of the pest control program.

A New Multiplex TaqMan qPCR for Precise Detection and Quantification of Clavibacter michiganensis in Seeds and Plant Tissue.

Bacterial canker of tomato caused by Clavibacter michiganensis (Cm) is one of the most devastating bacterial diseases affecting the tomato industry worldwide. As the result of Cm colonization of the xylem, the susceptible host shows typical symptoms of wilt, marginal leaf necrosis, stem cankers, and ultimately plant death. However, what makes Cm an even more dangerous pathogen is its ability to infect seeds and plants without causing symptoms. Unfortunately, there are no resistant cultivars or effective chemical or biological control methods available to growers against Cm. Its control relies heavily on prevention. The implementation of a rapid and accurate detection tool is imperative to monitor the presence of Cm and prevent its spread. In this study, we developed a specific and sensitive multiplex TaqMan qPCR assay to detect Cm and distinguish it from related bacterial species that affect tomato plants. Two Cm chromosomal virulence-related genes, rhuM and tomA, were used as specific targets. The plant internal control tubulin alpha-3 was included in each of the multiplexes to improve the reliability of the assay. Specificity was evaluated with 37 bacterial strains including other Clavibacter spp. and related and unrelated bacterial pathogens from different geographic locations affecting a wide variety of hosts. Results showed that the assay is able to discriminate Cm strains from other related bacteria. The assay was validated on tissue and seed samples following artificial infection, and all tested samples accurately detected the presence of Cm. The tool described here is highly specific, sensitive, and reliable for the detection of Cm and allows the quantification of Cm in seeds, roots, stems, and leaves. The diagnostic assay can also be adapted for multiple purposes such as seed certification programs, surveillance, biosafety, the effectiveness of control methods, border protection, and epidemiological studies.[Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Biological Control Options for the Management of Tadpole Shrimp (Triops longicaudatus (LeConte)) in California Rice

Tadpole shrimp (Triops longicaudatus) has become a major pest for California rice farmers. Currently, management relies solely on the insecticide lambda-cyhalothrin. However, resistance to this pyrethroid was confirmed in 2016; thus, identifying an effective and practical biological control method for TPS is a priority. Field trials were conducted from 2017 to 2018 to (1) evaluate the efficacy of the predatory fish Gambusia affinis and the predatory beetles, Laccophilus maculosus (Say) and Tropisternus lateralis (Fabricius), in controlling TPS, (2) test the efficacy of several inoculation rates of Gambusia affinis at controlling TPS and (3) to explore early indicators of TPS activity and damage as monitoring tools. Both Gambusia affinis and the predatory beetle treatments were not significantly different from the commercial standard (lambda-cyhalothrin). Both four and five Gambusia per 1 m2 controlled TPS as well as lambda-cyhalothrin, and we observed that Gambusia affinis was able to reproduce in the field. Water turbidity was significantly correlated with TPS counts (R = 0.85, N = 20, p < 0.0001 (2017); R = 0.58, N = 30, p = 0.0007 (2018)). The number of dislodged seedlings was less reliably correlated with TPS count; in 2017, correlations were significant (R = 0.84, N = 20, p < 0.0001); however, in 2018, correlations were not significant (R = 0.18, N = 30, p = 0.35). With further refinement, water turbidity could play a valuable role in monitoring TPS populations.

Three Ecological Models to Evaluate the Effectiveness of Trichoderma spp. for Suppressing Aflatoxigenic Aspergillus flavus and Aspergillus parasiticus.

Chemical pesticides help reduce crop loss during production and storage. However, the carbon footprints and ecological costs associated with this strategy are unsustainable. Here, we used three in vitro models to characterize how different Trichoderma species interact with two aflatoxin producers, Aspergillus flavus and Aspergillus parasiticus, to help develop a climate-resilient biological control strategy against aflatoxigenic Aspergillus species. The growth rate of Trichoderma species is a critical factor in suppressing aflatoxigenic strains via physical interactions. The dual plate assay suggests that Trichoderma mainly suppresses A. flavus via antibiosis, whereas the suppression of A. parasiticus occurs through mycoparasitism. Volatile organic compounds (VOCs) produced by Trichoderma inhibited the growth of A. parasiticus (34.6 ± 3.3%) and A. flavus (20.9 ± 1.6%). The VOCs released by T. asperellum BTU and T. harzianum OSK-34 were most effective in suppressing A. flavus growth. Metabolites secreted by T. asperellum OSK-38, T. asperellum BTU, T. virens OSK-13, and T. virens OSK-36 reduced the growth of both aflatoxigenic species. Overall, T. asperellum BTU was the most effective at suppressing the growth and aflatoxin B1 production of both species across all models. This work will guide efforts to screen for effective biological control agents to mitigate aflatoxin accumulation.

Antagonistic and Plant Growth-Promoting Properties of Streptomyces F2 Isolated from Vineyard Soil

Streptomyces can produce secondary metabolites with a wide range of activities and is often used in agriculture as a biocontrol strain to control soil-borne diseases. Screening and isolation from infected soil is an effective method to obtain active strains. In this study, the best antagonistic inter-root growth-promoting bacteria were isolated from grapevine inter-root soil samples, and strain F2 was identified as Streptomyces sp. based on morphological, physiological, and biochemical characteristics as well as 16S rDNA sequencing results. The results showed that the fermentation broth/liquid and sterile filtrate of strain F2 exhibited antagonistic effects against 10 plant pathogens, with an inhibition rate reaching up to 80%. Notably, two of them exhibited remarkable inhibitory effects against Phytophthora capsici with inhibition rates of 80.58% and 87.71%, respectively. The P. capsici leaf control experiment revealed that the control effect of strain F2 fermentation liquid on P. capsici filaments was 61.09%. Furthermore, indoor pot experiments demonstrated that the fermentation liquid of strain F2 had a significant inhibitory effect on pepper blight, with a maximum inhibition of 83.31%. Antagonistic factor analysis indicated that strain F2 had specific organophosphorus hydrolysis, nitrogen fixation, extracellular protease secretion, and IAA production capabilities. Additionally, root treatment with strain F2’s fermentation liquid significantly enhanced capsicum growth. Taking together, Streptomyces F2 not only exhibits a wide-spectrum antagonistic effect against plant pathogens but also promotes plant growth, which suggests that Streptomyces F2 can be used as an effective biological control resource and provides important theoretical support for the application of Streptomyces F2.