Plant Biological Control Research Articles

The biological potential of a product containing Pythium oligandrum against Uncinaria stenocephala (Railliet, 1884) larvae

Pythium oligandrum is an oomycete commonly used in the biological control of plant and vegetable pests. In veterinary medicine is used to treat dermatophytosis produced by Microsporum canis. It acts as an antagonist, negatively influencing the development of other fungi. Through hydrolytic enzymes, such as kinase and cellulase, it destroys the cell wall and the internal cytoplasmic content. Many fungi are considered nematophagous. This potential has not been exploited for Pythium oligandrum, which is why in this study the potential larvicidal action against Uncinaria stenocephala larvae was investigated.Ecosin® product, which contains P. oligandrum and other excipients, was used. A solution was prepared according to manufacturer. The Uncinaria stenocephala larvae were exposed to this substance and the action was investigated after 7 days. The results obtained showed 37.23% larval reduction.Being an eco-friendly product, further studies are needed to improve the protocol for its use in cleaning spaces and surfaces in veterinary clinics, where various parasitic forms (larvae or eggs) are found.

Phyllosphere Microorganisms: Sources, Drivers, and Their Interactions with Plant Hosts.

The leaves of plants are colonized by various microorganisms. In comparison to the rhizosphere, less is known about the characteristics and ecological functions of phyllosphere microorganisms. Phyllosphere microorganisms mainly originate from soil, air, and seeds. The composition of phyllosphere microorganisms is mainly affected by ecological and abiotic factors. Phyllosphere microorganisms execute multiple ecological functions by influencing leaf functions and longevity, seed mass, fruit development, and homeostasis of host growth. A plant can respond to phyllosphere microorganisms by secondary metabolite secretion and its immune system. Meanwhile, phyllosphere microorganisms play an important role in ecological stability and environmental safety assessment. However, as a result of the instability of the phyllosphere environment and the poor cultivability of phyllosphere microorganisms in the current research, there are still many limitations, such as the lack of insight into the mechanisms of plant-microorganism interactions, the roles of phyllosphere microorganisms in plant growth processes, the responses of phyllosphere microorganisms to plant metabolites, etc. This review summarizes the latest progress made in the research of the phyllosphere in recent years. This is beneficial for deepening our understanding of phyllosphere microorganisms and promoting the research of plant-atmosphere interactions, plant pathogens, and plant biological control.

Regulatory Mechanism of Trap Formation in the Nematode-Trapping Fungi.

Nematode-trapping (NT) fungi play a significant role in the biological control of plant- parasitic nematodes. NT fungi, as a predator, can differentiate into specialized structures called “traps” to capture, kill, and consume nematodes at a nutrient-deprived condition. Therefore, trap formation is also an important indicator that NT fungi transition from a saprophytic to a predacious lifestyle. With the development of gene knockout and multiple omics such as genomics, transcriptomics, and metabolomics, increasing studies have tried to investigate the regulation mechanism of trap formation in NT fungi. This review summarizes the potential regulatory mechanism of trap formation in NT fungi based on the latest findings in this field. Signaling pathways have been confirmed to play an especially vital role in trap formation based on phenotypes of various mutants and multi-omics analysis, and the involvement of small molecule compounds, woronin body, peroxisome, autophagy, and pH-sensing receptors in the formation of traps are also discussed. In addition, we also highlight the research focus for elucidating the mechanism underlying trap formation of NT fungi in the future.

Use of Endophytic Trichoderma to Control Fruit Rot Phytophthora infestans, Growth and Yield in Tomato

Endophytic Trichoderma is a fungus found in plant tissue and has the potential as a plant biological control agent. The aim of this study was to study endophytic Trichoderma isolated from tomato roots, stems and leaves to control Phytophthora infestans fruit rot and growth and yield of tomato plants. The treatments that were tested were endophytic tricoderma isolated from the roots, stems and leaves of tomato plants and applied with doses of 50, 75, and 100 g per tomato plant, respectively. The experimental design used a completely randomized design with three replications. The observed variables were disease intensity, plant height, number of flowers formed, and number of fruits formed. The results showed that the endophytic Trichoderma used could control the pod rot disease of Phytophthora infestans as well as increase the growth and yield of tomato plants. Giving endophytic Trichodema from roots applied with a dose of 100 g is the best treatment because it can reduce disease intensity by 48.02%, while giving at a dose of 75 g per plant is the best treatment because it can increase plant height by 51.74%, the number of flowers formed amounted to 68.42% and the number of fruit formed was 74.70%.Keywords: Endophytic Tricoderma, Tomato, Phytophthora infestans.

Biocontrol of Phytopathogens under Aquaponics Systems

Aquaponics is an alternative method of food production that confers advantages of biological and economic resource preservations. Nonetheless, one of the main difficulties related to aquaponics systems could be the outbreak and dissemination of pathogens. Conventional treatments need to be administrated carefully because they could be harmful to human, fish, plants and beneficial microorganisms. Aquaponics practitioners are relatively helpless against plant diseases when they occur, especially in the case of root pathogens. Biological control agents (BCAs) may be an effective alternative to chemical inputs for dealing with pathogens of plants under aquaponics systems. Research of BCAs on aquaponics systems is limited, but there are numerous publications on the use of BCAs to control plant pathogens under soilless systems which confirm its potential use on aquaponics systems. The present review summarized the principal plant pathogens, the conventional and alternative BCA treatments on aquaponics systems, while considering related research on aquaculture and soilless systems (i.e., hydroponic) for its applicability to aquaponics and future perspectives related to biological control. Finally, we emphasized the case that aquaponics systems provide relatively untapped potential for research on plant biological control agents. Biological control has the potential to reduce the perturbation effects of conventional treatments on microbial communities, fish and plant physiology, and the whole function of the aquaponics system.

Modeling Top-Down and Bottom-Up Drivers of a Regime Shift in Invasive Aquatic Plant Stable States.

The evidence for alternate stable states characterized by dominance of either floating or submerged plant dominance is well established. Inspired by an existing model and controlled experiments, we conceptually describe a dynamic that we have observed in the field using a simple model, the aim of which was to investigate key interactions of the shift between invasive floating and invasive submerged plant dominance, driven by the rapid decomposition of floating plants as a consequence of herbivory by biological control agents. This study showed that the rate of switch between floating and submerged invasive plant dominance, and the point in time at which the switch occurs, is dependent on the nutrient status of the water and the density of biological control agents on floating plant populations. Therefore, top-down invasive plant biological control efforts using natural enemies can affect systems on a wider scale than the intended agent – plant level, and can be significantly altered by bottom-up changes to the system, i.e., nutrient loading. The implications of this are essential for understanding the multiple roles invasive plants and their control have upon ecosystem dynamics. The results emphasize the importance of multi-trophic considerations for future invasive plant management and offer evidence for new pathways of invasion. The model outputs support the conclusion that, after the shift and in the absence of effective intervention, a submerged invasive stable state will persist.

Biological control of invasive aquatic and wetland plants by arthropods: a meta-analysis of data from the last three decades

Results from the last three decades of aquatic and wetland plant biological control by arthropods were combined using meta-analytical techniques to provide an objective, quantitative understanding of control efficacy that cannot be provided by available narrative reviews. Analyses were performed to determine if differences exist in how well diverse biocontrol agents perform, and if experimental design can impact study results. Across all analyses, biocontrol of the included plants was generally successful. Though little heterogeneity in efficacy was seen between the individual biocontrol agents used, all experimental design analyses showed significant differences between respective study types. Thus, study design can significantly impact the results of biocontrol studies. From these results, we suggest that field studies with controls be performed using subsamples of an area (quadrats, transects, etc.), with biomass or density being the plant variable measured. More long-term (two or more years) and non-target effect studies could also be performed in the future.

Multicellular behaviour and production of a wide variety of toxic substances support usage of Bacillus subtilis as a powerful biocontrol agent.

Intensive cultivation of plants in the monoculture field system in order to feed the continuously growing human population creates a need for their protection from the variety of natural competitors such as: bacteria, fungi, insects as well as other plants. The increase in the use of chemical substances in the 20th century has brought many effective solutions for the agriculture. However, it was extremely difficult to obtain a substance, which would be directed solely against a specific plant pathogen and would not be harmful for the environment. In the late 1900's scientists began trying to use natural antagonisms between resident soil organism to protect plants. This phenomenon was named biocontrol. Biological control of plants by microorganisms is a very promising alternative to an extended use of pesticides, which are often expensive and accumulate in plants or soil, having adverse effects on humans. Nonpathogenic soil bacteria living in association with roots of higher plants enhance their adaptive potential and, moreover, they can be beneficial for their growth. Here, we present the current status of the use of Bacillus subtilis in biocontrol. This prevalent inhabitant of soil is widely recognized as a powerful biocontrol agent. Naturally present in the immediate vicinity of plant roots, B. subtilis is able to maintain stable contact with higher plants and promote their growth. In addition, due to its broad host range, its ability to form endospores and produce different biologically active compounds with a broad spectrum of activity, B. subtilis as well as other Bacilli are potentially useful as biocontrol agents.

Management of the Antagonistic Potential in Agricultural Ecosystems for the Biological Control of Plant Parasitic Nematodes

Management of the Antagonistic Potential in Agricultural Ecosystems for the Biological Control of Plant Parasitic Nematodes

The Nature and Practice of Biological Control of Plant Pathogens.R. James Cook , Kenneth F. Baker

<i>The Nature and Practice of Biological Control of Plant Pathogens.</i>R. James Cook , Kenneth F. Baker