Microbial Biopesticides Research Articles

Viability of Metarhizium anisopliae conidia (metsch.) Sorok preserved in packages containing silica gel

Background The entomopathogenic fungi are important microbial agents for their efficient performance as microbial biopesticides in pest control. The development of commercial products formulated with entomopathogenic fungi is in a promising market for biopesticides. However, the fungi can lose their viability when exposed to unfavorable conditions of temperature, humidity and ultraviolet radiation, affecting the life of conidia. Among these constraints, there is the relative humidity through the presence of free water in formulated as one of the main factors that affect the viability of the organism in the form and function of storage time. The use of desiccant agents, such as silica gel, may be a viable alternative to favor the retention of moisture in the air, reducing the adsorption of water molecules by the system. Thus, the aim of this study was to determine the efficiency of silica gel in maintaining the viability of dry conidia of Metarhizium anisopliae.

Bt technology -the way forward

Bacillus thuringiensis (Bt) is a Gram-positive soil bacterium, has been isolated from a range of habitats including soil, grain dust, phylloplane and dead insects. It is characterized by its ability to produce crystalline inclusions called ''endotoxin during sporulation. The crystalline inclusions (Cry and Cyt proteins), along with the spores, have a great potential to control a number of insect pests belonging to the order Lepidoptera, Diptera, Coleoptera, Hemiptera and Hymenoptera. Besides Bt may also control nematodes. Therefore, they represent a valuable tool for Integrated Pest Management (IPM). Bt is one the most important microbial biopesticides produced in the world, accounting for 1-2% of the global insecticide market and is responsible for over 90% of all biopesticide sales. The widespread occurrence of this bacterium and interest in the use of Bt products as an alternative to chemical insecticides stimulated the isolation of native Bt strains in many parts of the world. The characterization may also be used to predict insecticidal activity, determine ecological distribution, and identify new cry genes. Besides being an important component of studying Bt resources, the characterization of Cry proteins and its genotypic composition may help understanding its insecticidal activity. Bt also produces other important toxins such as: phospholipases, proteases, quinases, α exotoxins, β exotoxins, VIP (Vegetative Insecticidal Proteins), and δ endotoxins (crystalline inclusions). Bt harbors more than 72 classes of Cry protein, the most common proteins used in transgenic plants. Table ​Table11 below shows all Bt genes present today in transgenic plants in Brazil. Table 1 Bt genes currently deployed in transgenic crops in Brazil Abroad proteins Cry34 and 35 have been used in transgenic crops. Despite the great number of Cry proteins described and more than 600 genes from cry1Aa1 to cry72, not many different proteins have been cloned in crops nowadays. There are many different perspectives in Bt technology in Brazil besides the use in programs of transgenic crops. The demand for the use of Bt based biopesticides has increased in many Brazilian regions. Some important factors have contributed as the introduction of the new pest Helicoverpa armigera that has attacked crops such as maize, cotton, soybean, millet, sorghum, beans, green peppers, tomato, okra etc. Another important factor is because of Due to a favorable climate, crops are planted all over the year, and the farmers plant a second crop of corn or cotton called the safrinha. This new scheme of crop rotation is to first plant a crop of rain-fed such as rice, soybean or maize, and then after these crops are harvested, plant a second crop of soybean, sorghum or even maize. Safrinha can also be defined as a farming strategy whereby the farmer takes advantage of a long tropical growing season to produce two crops in a single growing season, thereby maximizing revenue per acre. So, it is paramount to continue the research on Bt to find new and more efficient genes, and produce Bt based biopesticides feasible and cheap to the market.

Antimicrobial Activities of Novel Mannosyl Lipids Isolated from the Biocontrol Fungus Simplicillium lamellicola BCP against Phytopathogenic Bacteria

The antagonistic fungus Simplicillium lamellicola BCP has been developed as a microbial biopesticide that effectively controls the development of various plant diseases caused by both pathogenic bacteria and pathogenic fungi. Antibacterial bioassay-directed fractionation was used to isolate mannosyl lipids from S. lamellicola BCP, and the structures of these compounds were elucidated using spectral analysis and chemical degradation. Three novel mannosyl lipids were characterized and identified as halymecins F and G and (3R,5R)-3-O-β-D-mannosyl-3,5-dihydrodecanoic acid. Massoia lactone and (3R, 5R)-3-hydroxydecan-5-olide were also isolated from S. lamellicola BCP. The three novel compounds inhibited the growth of the majority of phytopathogenic bacteria that were tested, and halymecin F displayed the strongest antibacterial activity. Agrobacterium tumefaciens was the most sensitive to the three novel compounds, with IC₅₀ values ranging from 1.58 to 24.8 μg/mL. The ethyl acetate extract of the fermentation broth from the antagonistic fungus effectively reduced the bacterial wilt caused by Ralstonia solanacearum on tomato seedlings. These results indicate that S. lamellicola BCP suppresses the development of plant bacterial diseases through the production of antibacterial metabolites.

Biological control of fire blight of apple and pear with antagonistic Lactobacillus plantarum

Lactic acid bacteria (LAB) can be a source of biological control agents (BCA) of fire blight disease. Several species of LAB are inhabitants of plants and are currently used as biopreservatives of food because of their antagonistic properties against bacteria, and are considered as generally safe. Candidates to BCA were selected from a large collection of LAB strains obtained from plant environments. Strains were first chosen based on the consistency of the suppressive effect against E. amylovora infections in detached plant organs (flowers, fruits and leaves). Lactobacillus plantarum strains PC40, PM411, TC54 and TC92 were effective against E. amylovora in most of the experiments performed. Besides, strains PM411, TC54 and TC92 had strong antagonistic activity against E. amylovora and also other target bacteria, and presented genes involved in plantaricin biosynthesis (plnJ, plnK, plnL, plnR and plnEF). The strains efficiently colonized pear and apple flowers; they maintained stable populations for at least 1 week under high RH conditions, and survived at low RH conditions. They were effective in preventing fire blight on pear flowers, fruits and leaves, as well as in whole plants and in a semi-field blossom assay. The present study confirms the potential of certain strains of L. plantarum to be used as active ingredient of microbial biopesticides for fire blight control that could be eventually extended to other plant bacterial diseases.

RNA-Seq Study of Microbially Induced Hemocyte Transcripts from Larval Heliothis virescens (Lepidoptera: Noctuidae).

Larvae of the tobacco budworm are major polyphagous pests throughout the Americas. Development of effective microbial biopesticides for this and related noctuid pests has been stymied by the natural resistance mediated innate immune response. Hemocytes play an early and central role in activating and coordinating immune responses to entomopathogens. To approach this problem we completed RNA-seq expression profiling of hemocytes collected from larvae following an in vivo challenge with bacterial and fungal cell wall components to elicit an immune response. A de novo exome assembly was constructed by combination of sequence tags from all treatments. Sequence tags from each treatment were aligned separately with the assembly to measure expression. The resulting table of differential expression had >22,000 assemblies each with a distinct combination of annotation and expression. Within these assemblies >1,400 were upregulated and >1,500 downregulated by immune activation with bacteria or fungi. Orthologs to innate immune components of other insects were identified including pattern recognition, signal transduction pathways, antimicrobial peptides and enzymes, melanization and coagulation. Additionally orthologs of components regulating hemocytic functions such as autophagy, apoptosis, phagocytosis and nodulation were identified. Associated cellular oxidative defenses and detoxification responses were identified providing a comprehensive snapshot of the early response to elicitation.

Entomopathogenic nematodes, a potential microbial biopesticide: mass production and commercialisation status – a mini review

Parasitic nematodes have several important attributes that make them excellent candidates for biological control of soil insects. These nematodes can be produced by in vivo by baiting technique on insects and commercially by in vitro solid/liquid culturing. Numerous insect pests on many different crops are being controlled by these insect parasitic nematodes, including root weevils, flea beetles, mint root borer, colorado potato beetle, white grubs, caterpillars and plant parasitic root nematode, e.g. root-knot nematodes. Utilisation of entomopathogenic nematodes (EPN) has raised intense interest and has been a growing concern globally mainly because of its potential efficiency, exemption from registration and other impressive attributes for utilising against the control of soil dwelling pests. This review highlights the mass production, commercialisation and utilisation of EPN as microbial biopesticide in bio-intensive pest management programmes.

Microbial biopesticides: opportunities and challenges.

Abstract Pesticides based on microorganisms and their products have proven to be highly effective, species specific and eco-friendly in nature, leading to their adoption in pest management strategies around the world. The microbial biopesticide market constitutes about 90% of total biopesticides and there is ample scope for further development in agriculture and public health, although there are challenges as well. This article reviews the various microbial biopesticides that are commercially available, the different approaches for their production and development, the recent technological advances and the challenges faced by the microbial biopesticide field in the future.

Improving Formulations for Biopesticides: Enhanced UV Protection for Beneficial Microbes

Abstract As environmentally conscious consumers push for environmentally friendly pest control, interest in controlling insects with microbial-based biopesticides increases. Specific bacteria, fungi, and viruses can provide effective pest control when sprayed onto plants. However, these microbes are rapidly degraded by sunlight, which limits their field efficacy. One strategy to combat this degradation is to develop formulations to protect the beneficial microbe from sunlight energy, specifically the ultraviolet (UV) wavelengths. Formulation technologies (ingredients and processes) continue to be developed and adapted to provide UV protection. We have been conducting research on soyscreen and lignin as formulation ingredients to provide UV protection to a variety of insect pathogens. Soyscreen consists of feruloylated soy glycerides (FSG) specifically developed to absorb UV energy. Previous research demonstrated that FSG in oil-based formulations protected the viability of hydrophobic fungal conidia of Beauveria bassiana exposed to simulated sunlight, but not when applied in the field to oil absorbing substrates, including cabbage and tree bark. To prevent the FSG from being absorbed, the oil was encapsulated in starch using a jet cooking process forming a product with improved UV absorption. These starch-FSG composites may be useful to formulate aqueous-based systems without synthetic surfactants to deliver and protect microbial biopesticides. Lignin has been used with a spray-drying process to encapsulate insecticidal viruses, which are extremely sensitive to degradation by sunlight. The insoluble particles remain intact during application and can extend insecticidal activity by several days. Techniques are currently being developed to produce an adjuvant formulation with water-soluble lignin in an effort to provide UV protection for a broader range of commercial pesticides. These technologies are considered to be environmentally benign and are intended to fit in the biopesticide concept. The versatility of combining various products and processes provides variable formulations, some of which are suitable for specific biopesticide applications.

Canadian innovations in microbial biopesticides†

For many years, researchers have been sceptical as to whether microbial biological control agents, and in particular biopesticides, would be developed for use in areas other than greenhouses and forestry. This perception is slowly changing as the increased development and use of biopesticides in Canada is moving from being a novelty to a reality. This paper examines the role of biopesticides in Canada and the nine stages required to take a microbial biopesticide from discovery through product development, striving for commercialization and adoption by the end user. It highlights examples of Canadian biopesticide innovations that have moved through the innovation chain, illustrating the challenges and rewards along the way.

Environmental factors determining the epidemiology and population genetic structure of the Bacillus cereus group in the field.

Bacillus thuringiensis (Bt) and its insecticidal toxins are widely exploited in microbial biopesticides and genetically modified crops. Its population biology is, however, poorly understood. Important issues for the safe, sustainable exploitation of Bt include understanding how selection maintains expression of insecticidal toxins in nature, whether entomopathogenic Bt is ecologically distinct from related human pathogens in the Bacillus cereus group, and how the use of microbial pesticides alters natural bacterial populations. We addressed these questions with a MLST scheme applied to a field experiment in which we excluded/added insect hosts and microbial pesticides in a factorial design. The presence of insects increased the density of Bt/B. cereus in the soil and the proportion of strains expressing insecticidal toxins. We found a near-epidemic population structure dominated by a single entomopathogenic genotype (ST8) in sprayed and unsprayed enclosures. Biopesticidal ST8 proliferated in hosts after spraying but was also found naturally associated with leaves more than any other genotype. In an independent experiment several ST8 isolates proved better than a range of non-pathogenic STs at endophytic and epiphytic colonization of seedlings from soil. This is the first experimental demonstration of Bt behaving as a specialized insect pathogen in the field. These data provide a basis for understanding both Bt ecology and the influence of anthropogenic factors on Bt populations. This natural population of Bt showed habitat associations and a population structure that differed markedly from previous MLST studies of less ecologically coherent B. cereus sample collections. The host-specific adaptations of ST8, its close association with its toxin plasmid and its high prevalence within its clade are analogous to the biology of Bacillus anthracis. This prevalence also suggests that selection for resistance to the insecticidal toxins of ST8 will have been stronger than for other toxin classes.

Effect of Temperature and Storage Time on Shelf Life of Mycoherbicidal Products of <i>Colletotrichum dematium</i> FGCC#20

Problem statement: The storage environment can have a drastic impact on the stabilization of microbial biopesticides. As a general rule, storing microbial preparation at lower temperature increase long term survivelity. Approach: Optimization of shelf life is critically important for biocontrol products containing living microorganisms. Conidia of Colletotrichum dematium, (FGCC#20) a fungal pathogen of the weed, Parthenium hysterophorus were produced in solid agrowaste substrate. After solid based formulation, formulated mycoherbicidal products were conditioned at room temperature and at 4°C temp in different storage periods. Results: The longest shelf-life (conidial inoculums viability) was found in formulated products stored at 4°C temperature. At this temperature 4°C pesta (Wheat bran + Keolin) granules were 80% viable for 3 months and 10-15% viable after one month. Conclusion: The temperature had a renounced effect on the shelf life of the formulated products during storage. Maximum shelf life was observed in pesta granules for at least 1 year at 4°C would be adequate for commercialization.

Social and economic drivers shaping the future of biological control: A Canadian perspective on the factors affecting the development and use of microbial biopesticides

Globally, the use of biopesticides is growing annually while the use of traditional pesticides is on the decline. North America uses the largest percentage of the biopesticide market share at 44%, followed by the EU and Oceania with 20% each, South and Latin American countries with 10%, about 6% in Asia and India. Although biopesticide growth is projected at 10% annually, it is highly variable among the regions constrained by factors such as regulatory hurdles, public and political attitudes, and limitations for market expansion. Microbial biopesticides have been registered in Canada for 35 years, but the number of registrations for commercial, restricted-industry and domestic uses has significantly increased over the past 10 years. The early Canadian biopesticides registered by pest control category were Bacillus thuringiensis in 1972 as the first bioinsecticide, Agrobacterium radiobacter in 1989 as the first biobacteriocide, Colletotrichum gloeosporioides f.sp. malvae in 1992 as the first bioherbicide, and Streptomyces griseoviridis in 1999 as the first biofungicide. Between 1972 and 2008, the Pest Management Regulatory Agency approved registration of 24 microbially active substances with 83 formulations. The majority of the registrations (55/83) occurred since 2000 and at the beginning of 2008 there were 10 new products (a combination of new active substances, strains, formulations, and uses) under regulatory evaluation. This paper examines the evolution of microbial biopesticides in Canada illustrating how the actions of the government, the people, and the industry have led to changes in legislation, policy, and programming that spurred momentum for new microbial pest control products in recent years and created a model system for future microbial biopesticide discovery, development, and implementation that could be adopted throughout the world.

Microbial biopesticides for integrated crop management: an assessment of environmental and regulatory sustainability

Herbivorous insects and mites, plant diseases and weeds are major impediments to the production of food crops and are increasingly difficult to control with conventional chemicals. This paper focuses on microbial control agents with an emphasis on augmentation. There are marked differences in the availability of products in different countries which can be explained in terms of differences in their regulatory systems. Regulatory failure arises from the application of an inappropriate synthetic pesticides model. An understanding of regulatory innovation is necessary to overcome these problems. Two attempts at remedying regulatory failure in the UK and the Netherlands are assessed. Scientific advances can feed directly into the regulatory process and foster regulatory innovation.

Toxicity of biopesticides and synthetic insecticides to egg parasitoid, Trichogramma chilonis Ishii, and coccinellid predator, Cheilomenes sexmaculata (Fabricius).

Toxicity of biopesticides and synthetic insecticides was assayed for egg parasitoid, Trichogramma chilonis Ishii and coccinellid predator, Cheilomenes sexmaculata ( Fabrieius) under laboratory conditions. Neem seed kernel extract (NSKE 5%), custard apple seed extract (CASE 5%), pongamia seed extract (PSE 5%), neem oil (2%) and pongamia oil (2%) were compared with commercial neem formulation (0.2%) for their toxic effect Synthetic insecticides like imidacloprid (0.01%), acetamiprid (0.002%), thiomethoxam (0.02%), profenophos (0.05%), and carbosulfan (0.14%) were compared with monocrotophos (0.05%) for their toxicity to T. chilonis and C. sexmaculata . Most of the botanicals were found safe to T. chilonis and C. sexmaculata . Among six insecticides tested, carbosulfan was found to be highly toxic to T. chilonis and C. sexmaculata , followed by acetamiprid. imidacloprid was relatively less toxic to botb species. Microbial biopesticide, Bacillus thuringiensis (Bt) was also found safe to both species.

IgE sensitization to bacterial and fungal biopesticides in a cohort of Danish greenhouse workers: the BIOGART study.

The use of biopesticides in agriculture may implicate new risks of work-related allergic reactions. Sera were tested from the BIOGART project, a longitudinal respiratory health study among >300 Danish greenhouse workers. IgE was measured by enzyme immunoassay (EIA) with extracts of biopesticide products containing Bacillus thuringiensis (BT) or Verticillium lecanii (Vert). Many sera had detectable IgE to BT (23-29%) or Vert (9-21%). IgE titers from the 2- and 3-year follow-up (n=230) were highly correlated, with discordant results in <15%. IgE titers to different BT, or to different Verticillium products were also significantly correlated (both r >0.70), whereas IgE anti-BT and anti-Verticillium showed no correlation at all. Exposure to these microbial biopesticides may confer a risk of IgE-mediated sensitization. In future research there is a need to identify allergenic components in the preparations, perform studies on non-exposed controls and analyze the relation between sensitization and health parameters.

Biopesticides. Use and Delivery

Biopesticides: Present Status and Future Prospects, Julius J. Menn and Franklin R. Hall. PART I. Projections on Opportunities for Biopesticides in Crop Protection. The North American Scenario, Jerry Caulder. Microbial Biopesticides: The European Scene, Tariq M. Butt, John G. Harris, and Keith A. Powell. Developing Countries, Balasubramanyan Sugavanam and Xie Tianjian. Pesticide Policy Influences on Biopesticide Technologies, Noel D. Uri. PART II. Biofungicides. Commercial Development of Biofungicides, Rafael Hofstein and Andrew C. Chapple. Biological Control of Seedling Diseases, K. Prakesh Hebbar and Robert D. Lumsden. Joint Action of Microbials for Disease Control, Claude Alabouvette and Philippe Lemanceau. PART III. Bioinsecticides. Neem and Related Natural Products, Murray B. Isman. Commercial Experience with Neem Products, James F. Walter. Fermentation-Derived Insecticide Control Agents: The Spinosyns, Thomas C. Sparks, Gary D. Thompson, Herbert A. Kirst, Mark B. Hertlein, Jon S. Mynderse, Jan R. Turner, and Thomas V. Worden. Bacillus thuringiensis: Natural and Recombinant Bioinsecticide Products, James A. Baum, T. B. Johnson, and Bruce C. Carlton. Transgenic Plants Expressing Toxins from Bacillus thuringiensis, Jonnie N. Jenkins. Production, Delivery, and Use of Mycoinsecticides for Control of Insect Pests on Field Crops, Steven P. Wraight and Raymond I. Carruthers. Entomopathogenic Nematodes, Parwinder Grewal and Ramon Georgis. Naturally Occurring Baculoviruses for Insect Pest Control, Brian A. Federici. Recombinant Baculoiviruses, Michael F. Treacy. Joint Action of Baculoviruses and Other Control Agents, William F. McCutchen and Lindsey Flexner. PART IV. Bioherbicides. Mycoherbicides, Alice L. Pilgeram and David C. Sands. Formulation and Application of Plant Pathogens for Biological Weed Control, Nina K. Zidack and Paul C. Quimby. PART V. Other Biorational Technologies. Phereomones for Insect Control: Strategies and Successes, D. R. Thomson, L. J. Gut, and J. W. Jenkins. PART VI. Registration of Biopesticides. The Federal Registration Process and Requirements for the United States, J. Thomas McClintock. IR-4 Biopesticide Program for Minor Crops, Christina L. Hartman and George M. Markley. Registration/Regulatory Requirements in Europe, Mike Neale and Phil Newton. Environmental and Regulatory Aspects: Industry View and Approach, Joseph D. Panetta. PART VII. Management Protocols. Formulations of Biopesticides, Susan M. Boyetchko, Eric Pedersen, Zamir K. Punja, and Munagala S. Reddy. Delivery Systems and Protocols for Biopesticides, Roy Bateman. Analysis, Monitoring, and Some Regulatory Implications, Jack R. Plimmer. Principles of Dose Aquisition for Bioinsecticides, Hugh F. Evans. Strategies for Resistance Management, Richard T. Roush. Field Management: Delivery of New Technologies to Growers, Mark E. Whalon and Deborah L. Norris. Index.

Utilization of natural enemies of Chilo spp. for management in Africa

Knowledge on the natural enemies of graminaceous stem borers is outlined, with special reference to mortality of Chilo spp. as crop pests in Africa. The quantitative scanty information available suggests that over 90% mortality of eggs and larvae takes place before the larvae become established as borers in the crop and that mortality of the older larvae and pupae is much lower. Possible manipulations of natural enemies to increase mortality further are reviewed. In view of the largely negative results of past classical biological control introductions the prospects do not appear very promising. However, the results do indicate some possibilities which should be investigated, notably trials with Apanteles spp. (Braconidae) and intra-continental redistribution of important species with restricted distributions. For short-term biological control, development of microbial biopesticides seems a more promising strategy than augmentation of insect parasitoids by breeding and release, particularly on small farms. A third possibility, enhancement of the action of native natural enemies by environmental manipulation, merits more attention as part of an integrated crop production approach to the improvement of the quantity and reliability of yields for the small farmer.