Location: Crop Bioprotection Research
2017 Annual Report
Objectives
Objective 1. Utilizing transcriptomics to link gene function to fungal morphogenesis, develop liquid culture methods for producing propagules of fungal biocontrol agents such as Metarhizium spp., Beauveria bassiana, and Mycoleptodiscus terrestris by optimizing nutritional and environmental conditions during fungal growth for optimal biocontrol efficacy and storage stability to control pests in agricultural, urban, and natural ecosystems.
Objective 2. Develop novel fungal formulation technologies through the selection and application of innovative processes and ingredients that lead to improved storage stability, product delivery, field stability, and efficacy of fungal pathogens for biocontrol of insects [Beauveria bassiana, Metarhizium spp., and Isaria fumosorosea] and weeds [Mycoleptodiscus terrestris].
Subobjective 2A: Evaluate the compatibility of improved entomopathogen formulations with representative corn pest resistance mechanisms for control of sweet corn pests.
Objective 3. Identify, chemically and behaviorally characterize, and deploy natural insect semiochemicals (pheromones/kairomones and plant volatiles) with microbial biocontrol agents for management of important agricultural insect pests such as brown marmorated stink bug and coffee berry borer.
Approach
Our approach to the development of production methods for fungal biocontrol agents will focus on the use of liquid fermentation techniques. We will identify defined or semi-defined media that support the growth of our fungal biocontrol agents. Propagule form yield, storage stability, and biocontrol efficacy are critical “fitness” factors that will be considered during medium optimization. Initially, we will focus on producing propagules of fungal biocontrol agents such as Metarhizium spp, Beauveria bassiana, and Mycoleptodiscus terrestris. We also will use transcriptomics to identify pathways that may impact these factors. We will evaluate the impact of culture harvest techniques, stabilization processes, and formulation ingredients on the physical characteristics, biological activity, storage stability, and field efficacy of selected biocontrol agents. Also, we will identify and chemically characterize insect attractants and deterrents and evaluate formulations for management of important agricultural insect pests such as the brown marmorated stink bug, coffee berry borer, polyphagous shot hole borer, and tea shot hole borer.
Progress Report
Significant progress was made in FY16 on Objectives 1 and 2 related to the production and formulation of microbial agents for controlling insects.
Under Objective 1, ARS scientists at Peoria, Illinois, continued to develop and optimize liquid culture production processes for beneficial fungi. Liquid culture techniques have focused on production of two diverse fungal structures: spores, ideal for insect control as foliar spray applications, and microsclerotia, fungal compositions ideal for use in granular formulations. Production and stabilization processes for microsclerotia of the insect-killing fungus Metarhizium were refined and efforts have focused on transferring this licensed patented ARS technology to the commercial partner. A patented ARS liquid culture production process for microsclerotia of the weed-killing fungus Mycoleptodiscus terrestris continues to be evaluated for control of the aquatic weeds Eurasian water milfoil and hydrilla. The use of microsclerotia of M. terrestris has garnered significant industry interests, and shows promise as a non-chemical bioherbicide for use in U.S. lakes and waterways.
Liquid culture fermentation methods were developed for the rapid production of high concentrations of blastospores of the insect-killing fungi Beauveria bassiana and Isaria fumosorosea. Both of these bioinsecticides are used extensively worldwide for the control of whiteflies, aphids, and other important insect pests. There is significant industry interest in this ARS patent-pending production process due to the high blastospore yields coupled with excellent desiccation tolerance, shelf life, and biocontrol efficacy.
Research continued on the development of liquid culture production processes for several additional beneficial fungi including: 1) Trichoderma, a fungal biocontrol agent used world-wide for the control of plant root diseases and for improving plant health, 2) Hirsutella citriformis, a beneficial fungus that has shown promise for controlling the Asian citrus psyllid, and 3) Purpureocilllium lilacinum, a fungus used for control of plant parasitic nematodes.
Under Objective 2, ARS scientists at Peoria, Illinois, developed drying and formulation processes that optimized the stability and efficacy of blastospores of Beauveria and Isaria, and of microsclerotia of the bioinsecticidal fungus Metarhizium. The blastospore formulations are excellent for spray applications on plant surfaces for control of whiteflies, aphids and thrips. Specifically, progress continues on developing and testing blastospore formulations of the bioinsecticide Isaria fumosorosea for use in controlling the Asian citrus psyllid. When applied to field grown plants, a mixed microbe formulation containing both Beauveria blastospores and the bacterium Bacillus thuringiensis (Bt) was shown to provide more effective pest control than either product alone.
ARS scientists at Peoria, Illinois, have also made substantial progress in developing shelf-stable, granular formulations of Metarhizium microsclerotia for use in controlling soil-dwelling insect pests including white grubs in turf, corn rootworm larvae, and other important insect pests in collaboration with university and ARS scientists. Collaboration continues with university scientists on the development of specific formulations of Metarhizium microsclerotia for application to trees for control of the Asian longhorned beetle. Granular formulations of Metarhizium microsclerotia are ideal for use in the soil environment, or in above ground applications onto trees, and new powdered formulations offer expanded opportunities for novel applications for pest control.
Our dried granular formulations of Metarhizium microsclerotial and Beauveria blastospores have shown excellent storage stability at room temperature. All of these formulation studies demonstrated the importance of water activity and storage atmosphere in optimizing the shelf-life of fungal microsclerotia and blastospores. Production and formulation processes have been successfully scaled to pilot plant levels of operation with the ability to supply kilogram quantities of product for field testing. Cooperative research with other ARS scientists offers the opportunities to develop and evaluate new ingredients for benefits to biopesticide formulations while maintaining the “natural” or “green” label.
Accomplishments
1. Stable fungal bioinsecticide. The insect-killing fungus, Beauveria bassiana, is used world-wide as a non-chemical control agent (bioinsecticide) for a wide range of insect pests including caterpillars whiteflies, aphids, and coffee berry borers. ARS scientists in Peoria, Illinois, recently developed a rapid, low-cost method for mass producing the yeast form (blastospore) of B. bassiana using liquid culture fermentation. Liquid culture-produced blastospores of B. bassiana contributed to synergistic pest control of caterpillar pests when applied with the beneficial bacterium Bacillus thuringiensis (Bt). In addition to being developed as a stand-alone dual-microbe product to provide biological pest control, a blastospore only product could be applied to transgenic Bt crops to help prevent the development of pesticide resistance to the Bt gene. The commercial adoption of these low cost, patent-pending production, formulation, and packaging methods for blastospores of B. bassiana will hasten the widespread use of this bioinsecticide as a replacement for chemical insecticides for pest control in row crop, horticulture, glasshouse, and urban environments.
ARS scientists in Peoria, Illinois, developed a website database to help scientists correctly identify entomopathogenic (insect killing) fungi. Entomopathogenic fungi are an important family of fungi that are produced as the active ingredient for many biological insecticides, which kill agricultural insect pests. The database is called “EntomopathogenID” and is available at http://199.133.98.43/Entomopathogen/. This database will allow for improved identification and more consistent nomenclature of these fungi. Improved identification of these agriculturally important fungi will enhance research, regulation and the communication of ideas related to these microbes. This research benefits U.S. farmers and consumers that rely on crops impacted by insect pests.
Review Publications
Hay, W.T., Behle, R.W., Fanta, G.F., Felker, F.C., Peterson, S.C., Selling, G.W. 2016. Effect of spray drying on the properties of amylose-hexadecylammonium chloride inclusion complexes. Carbohydrate Polymers. 157:1050-1056. doi: 10.1016/j.carbpol.2016.10.068.
Sayed, A.M., Behle, R.W. 2017. Evaluating a dual microbial agent biopesticide with Bacillus thuringiensis var. kurstaki and Beauveria bassiana blastospores. Biocontrol Science and Technology. 27(4):461-474. doi: 10.1080/09583157.2017.1303662.
Mascarin, G.M., Dunlap, C.A., Barrigossi, J.D., Quintela, E.D., De Noronha, N.C. 2016. First record of epizootics in the ocola skipper, Panoquina sp. (Lepidopera: Hesperiidae), caused by Isaria tenuipes in flooded rice fields of Central Brazil. Journal of Applied Microbiology. 122:1020-1028. doi: 10.1111/jam.13390.
Chow, A., Dunlap, C.A., Jackson, M.A., Flores, D., Patt, J.M., Setamou, M. 2016. Oviposition behavior and survival of Tamarixia radiata (Hymenoptera: Eulophidae), an ectoparasitoid of the Asian citrus psyllid, Diaphorina citri (Hemiptera: Liviidae), on hosts exposed to an entomopathogenic fungus. Journal of Economic Entomology. 109:1995-2005. doi: 10.1093/jee/tow164.
