Posts Tagged: fungi
Magical Mushrooms
With the cooler, damp weather due to the recent atmospheric storm and fog, you may have observed...
Entomopathogenic fungi-based biopesticides contribute to more than pest management
Entomopathogenic fungi (EPF) are those that infect various arthropods such as ticks, mites, and insects. There are two major groups of EPF that play an important role in pest suppression. Members of the order Entomophthorales are more host-specific and examples include Entomophaga maimaiga in spongy moth, Entomophthora muscae and Strongwellsea spp. in flies, Conidiobolus obscurus, Entomophthora planchoniana, Neozygites fresenii and Pandora neoaphidis in aphids, and Neozygites floridana in mites. These naturally occurring EPF are fastidious and cannot be mass produced on a commercial scale, but cause epizootics when host populations are high and environmental conditions are favorable resulting in significant pest suppression. On the other hand, members of the order Hypocreales are more generalistic pathogens and can be infective to a variety of arthropods. Beauveria bassiana, Cordyceps fumosorosea, Hirsutella thompsonii, and Metarhizium brunneum are some examples of hypocrealeans. These can be grown on artificial media on a commercial scale and several biopesticide formulations based on various isolates of these fungi are available in the US and elsewhere. Both entomophthoralean and hypocrealean fungi have the same mode of infection. When fungal spores come in contact with their host, they germinate and enter the host body through mechanical pressure and enzymatic degradation of the cuticle. They multiply inside the host, invade the tissues, and finally emerge from the cuticle to produce spores that continue the infection process.
With growing emphasis on sustainable crop production with safer pesticides, the market for biopesticides including EPF-based ones has been increasing. Newer EPF isolates and modern technology contributed to the development of improved formulations. EPF-based products can be used for soil-inhabiting pests or their life stages like root aphids, pupae of thrips, and wireworms to foliar feeders or above-ground pests including the members of Coleoptera, Diptera, Hemiptera, Orthoptera, Thysanoptera, and others. Considering their potential against a variety of pests on multiple crops, EPF-based pesticides should be an important part of integrated pest management (IPM) programs. However, there is a significant knowledge gap in effectively using EPF in IPM and fully exploring their potential in sustainable crop production.
Since EPF spores need to come in contact with the host, using them against the right pest or life stage is very important to obtain desired results. Sometimes, using EPF in combination or rotation with botanical or synthetic pesticides is more effective than using them alone against a particular pest (Dara 2013; 2015; 2016). As EPF formulations contain live fungi, label instructions should be followed for proper storage, transportation, tank-mixing, and application to maintain their efficacy. Compatibility can vary according to the EPF and its formulation, but studies showed that some isolates of Beauveria bassiana and Metarhizium anisopliae are compatible with several fungicides (Dara, et al., 2014; Roberti et al., 2017; Khun et al., 2021).
In addition to controlling arthropod pests, EPF being soilborne fungi also have a direct relationship with plants and other microbes. EPF colonize plant tissues and grow inside the plants in a phenomenon known as endophytism. Endophytic EPF grow as hyphae and do not produce spores. Although they cannot cause infection to pests feeding on those plants, they indirectly affect pests by reducing their fitness and survival by activating induced systemic resistance. When EPF are applied to soil, they form a mycorrhiza-like relationship with plant roots and help plants withstand biotic stresses and improve nutrient uptake. EPF can also antagonize plant pathogens through competitive displacement and antimicrobial activity. Thus soil and foliar application of EPF-based pesticides result in additional benefits in improving crop growth and health in addition to controlling pests through infection.
Several studies explored the non-entomopathogenic roles of EPF (Dara, 2019a). Soil application of B. bassiana had a positive impact on the survival, growth, and health of cabbage plants growing under water stress (Dara et al., 2017). Metarhizium brunneum also had a similar impact on plant growth in this study. Root and rhizosphere colonization by Metarhizium spp.improved shoot length and root weight in industrial hemp (Hu et al., 2023) and root colonization of Metarhizium robertsii alleviated hemp from salt and drought stress. Metarhizium spp. and B. bassiana transferred nitrogen from dead insects to the plant they colonized (Behie et al., 2012; Behie and Bidochka, 2014). These studies show the role of EPF in soil nitrogen cycle and how plants benefit from the endophytic relationship of EPF. Additionally, recent reports showed that endophytic B. bassiana induced the biosynthesis of flavonoids in oilseed rape (Muola et al., 2023) and flavonol content in licorice plants (Etsassala et al., 2023).
Seed treatment with B. bassiana increased plant height, stem diameter, number of leaves, shoots and apical buds, biomass, and total chlorophyll content in cotton and reduced cotton aphid (Aphis gossypii) populations (Mantzoukas et al., 2023). Similarly, endophytic B. bassiana significantly reduced the reproductive rate and populations of the Russian wheat aphid (Diuraphis noxia) in South African wheat (Motholo et al., 2023). In corn, endophytic B. bassiana and M. anisopliae negatively impacted the survival, development, and reproduction of the fall armyworm (Spodoptera frugiperda) (Altaf et al., 2023).
Soil application of B. bassiana, Cordyceps fumosorosea, and Metarhizium brunneum antagonized Fusarium oxysporum f.sp. vasinfectum in cotton as effectively as some biofungicides (Dara et al., 2020). Beauveria bassiana treatment at a higher rate provided significantly better protection than all other treatments in this study. Both B. bassiana and C. fumosorosea inhibited the growth of F. oxysporum in vitro (Yanagawa et al., 2021). In corn, endophytic M. robertsii promoted plant growth and reduced southern corn leaf blight caused by Cochliobolus heterostrophus (Imtiaz et al., 2023). Induced systemic resistance is thought to be responsible for this protection. Similarly, B. bassiana applied as seed treatment, seedling root dip, and foliar spray reduced the incidence of rice sheath blight caused by Rhizoctonia solani by 69% and its severity by 60% under field conditions (Deb et al., 2023). Beauveria bassiana also resulted in 71% of mycelial inhibition in R. solani through the production of cell wall degrading enzymes, release of secondary metabolites, and mycoparasitism.
Multiple recent studies showed that EPF also have a negative impact on plant-parasitic nematodes. Beauveria bassiana and C. fumosorosea reduced the survival ofthe root-knot nematode, Meloidogyne incognita, in vitro (Yanagawa et al., 2021). Similar to the nematophagous fungus Purpureocillium lilacinum, both B. bassiana and M. anisopliae were effective in reducing galls caused by M. incognita in tomato and cucumber (Karabörklü et al., 2022). Metarhizium anisopliae was as effective as P. lilacinum with 75% reduction in gall formation and 85% control of second instar juveniles in tomato. Beauveria bassiana and M. anisopliae also resulted in about 85% control of second instar juveniles in cucumber. In another study, soil application of B. bassiana significantly reduced nematode infestation in tomato roots and B. bassiana treatment caused 60% mortality in nematodes in a lab assay (Kim et al., 2023). Volatile organic compounds, 1-octen-3-ol and 3-octanone from M. brunneum attracted and killed another plant-parasitic nematode, Meloidogyne hapla, in lab assays (Khoja et al., 2021).
As many of these recent studies indicated, the non-entomopathogenic roles of EPF is a new area of applied research interest with tremendous practical benefits. In addition to direct pest control through infection, EPF as endophytes offer multiple benefits in suppressing pest populations by affecting their fitness, antagonizing plant pathogens and plant-parasitic nematodes, imparting drought and salt tolerance in plants, improving nutrient uptake, and promoting overall growth and health of plants. Using EPF-based biopesticides comes under the microbial control of IPM (Dara, 2019b) and will contribute to insecticide resistance management. Additionally, the non-target benefits of EPF will help growers optimize the use of other inputs and related costs. EPF can be very important in sustainable crop production and a thorough understanding of their biology, interactions with pests, plants, pathogens, and other biotic and abiotic factors, and effective use strategies will help achieve their full potential.
Note: This article was initially published in the December 2023 issue of CAPCA Adviser magazine.
References
Altaf, N., M. I. Ullah, M. Afzal, M. Arshad, S. Ali, M. Rizwan, L. A. Al-Shuraym, S. S. Alhelaify, and S. Sayed. 2023. Endophytic colonization by Beauveria bassiana and Metarhizium anisopliae in maize plants affects the fitness of Spodoptera frugiperda (Lepidoptera: Noctuidae). Microorganisms 11: 1067.
Behie, S. W. and M. J. Bidochka. 2014. Ubiquity of insect-derived nitrogen transfer to plants by endophytic insect-pathogenic fungi: an additional branch of the soil nitrogen cycle. Appl. Environ. Microbiol. 80: 1553-1560.
Behie, S. W., P. M. Zelisko, and M. J. Bidochka. 2012. Endophytic insect-parasitic fungi translocate nitrogen directly from insects to plants. Science 336: 1576-1577.
Dara, S. 2013. Microbial control as an important component of strawberry IPM. CAPCA Adviser, 16 (1): 29-32.
Dara, S. K. 2015. Root aphids and their management in organic celery. CAPCA Adviser 18 (5): 65-70.
Dara, S. K. 2016. IPM solutions for insect pests in California strawberries: efficacy of botanical, chemical, mechanical, and microbial options. CAPCA Adviser 19 (2): 40-46.
Dara, S. K. 2019a. Non-entomopathogenic roles of entomopathogenic fungi in promoting plant health and growth. Insects 10: 277.
Dara, S. K. 2019b. The new integrated pest management paradigm for the modern age. JIPM 10: 12.
Dara, S. K., S. S. Dara, and S.S.R. Dara. 2020. Managing Fusarium oxysporum f. sp. vasinfectum Race 4 with beneficial microorganisms including entomopathogenic fungi. Acta Horticulturae 1270: 111-116.
Dara, S. K., S.S.R. Dara, and S. S. Dara. 2017. Impact of entomopathogenic fungi on the growth, development, and health of cabbage growing under water stress. Am. J. Plant Sci. 8: 1224-1233.
Dara, S.S.R., S.S. Dara, A. Sahoo, H. Bellam, and S. K. Dara. 2014. Can entomopathogenic fungus Beauveria bassiana be used for pest management when fungicides are used for disease management? UCANR eJournal of Entomology and Biologicals October 23, 2014.
Deb, L., P. Dutta, M. K. Mandal and S. B. Singh. 2023. Antimicrobial traits of Beauveria bassiana against Rhizoctonia solani, the causal agent of sheath blight of rice under filed conditions. Plant Disease PDIS-04. https://doi.org/10.1094/PDIS-04-22-0806-RE.
Etsassala, N. G. E. R., N. Macuphe, I. Rhoda, F. Rautenbach and F. Nchu. 2023. An endophytic Beauveria bassiana (Hypocreales) strain enhances the flavonol contents of Helichrysum petiolare. In Sustainable Uses and Prospects of Medicinal Plants, eds. L. Kambizi and C Bvenura, CRC Press. pp 367-377.
Hu, S. and M. J. Bidochka. 2023. Colonization of hemp by Metarhizium and alleviation of salt and drought stress. 55th Annual meetings of the Society for Invertebrate Pathology, July 30-August 3, 2023, College Park, MD, pp. 56-57.
Hu, S., M. S. Mojahid, M. J. Bidochka. 2023. Root colonization of industrial hemp (Cannabis sativa L.) by the endophytic fungi Metarhizium and Pochonia improves growth. Industrial Crops and Products 198: 116716.
Imtiaz, A. M. M. Jiménez-Gasco, and M. E. Barbercheck. 2023. Endophytic Metarhizium robertsii suppresses the phytopathogen, Cochliobolus heterostrophus and modulates maize defenses. 55th Annual meetings of the Society for Invertebrate Pathology, July 30-August 3, 2023, College Park, MD, pp. 66-67.
Karabörklü, S., V. Aydinli and O. Dura. 2022. The potential of Beauveria bassiana and Metarhizium anisopliae in controlling the root-knot nematode Meloidogyne incognita in tomato and cucumber. J. Asia-Pacific Entomol. 25: 101846.
Khoja, S., K. M. Eltayef, I. Baxter, A. Myrta, J. C. Bull and T. Butt. 2021. Volatiles of the entomopathogenic fungus, Metarhizium brunneum, attract and kill plant parasitic nematodes. Biol. Con. 152: 104472.
Khun, K. K., G. J. Ash, M. M. Stevens, R. K. Huwer, B. A. Wilson. 2021. Compatibility of Metarhizium anisopliae and Beauveria bassiana with insecticides and fungicides used in macadamia production in Australia. Pest Manag. Sci. 77: 709-718.
Kim, K. J., S. E. Park, Y. Im, H. Yang and J. S. Kim. 2023. Drenching of Beauveria bassiana JEF-503 reduces the root knot nematode populations in soil. 55th Annual meetings of the Society for Invertebrate Pathology, July 30-August 3, 2023, College Park, MD, pp. 68.
Mantzoukas, S., V. Papantzikos, S. Katsogiannou, A. Papanikou, C. Koukidis, D. Servis, P. Eliopoulos, and G. Patakioutas. 2023. Biostimulant and bioinsecticidal effect of coating cotton seeds with endophytic Beauveria bassiana in semi-field conditions. Microorganisms 11: 2050.
Motholo, L. F., M. Booyse, J. L. Hatting, T. J. Tsilo, M. Lekhooa, and O. Thekisoe. 2023. Endophytic effect of the South African Beuaveria bassiana strain PPRI 7598 on the population growth and development of the Russian wheat aphid, Diuraphis noxia. Agriculture 13: 1060.
Moula, A., T. Birge, M. Helander, S. Mathew, V. Harazinova, K. Saikkonen, and B. Fuchs. 2023. Endophytic Beauveria bassiana induces biosynthesis of flavonoids in oilseed rape following both seed inoculation and natural colonization. Pest Manag. Sci. DOI 10.1002/ps.7672
Roberti, R. H. RIghini, A. Masetti, and S. Maini. 2017. Compatibility of Beauveria bassiana with fungicides in vitro and on zucchini plants infested with Trialeurodes vaporariorum. Biol. Con. 113: 39-44.
Yanagawa, A., N.P.R.A. Krishanti, A. Sugiyama, E. Chrysanti, S. K. Ragamustari, M. Kubo, C. Furumizu, S. Sawa, S. K. Dara, and M. Kobayashi. 2022. Control of Fusarium and nematodes by entomopathogenic fungi for organic production of Zingiber officinale. J. Natural Medicines, 76: 291-297.
Bot Canker: Have You Heard of It?
Ever heard of Bot canker? "Bot" stands for Botryosphaeria which is a plant disease that results...
Entomopathogenic microorganisms: modes of action and role in IPM
Entomopathogens are microorganisms that are pathogenic to arthropods such as insects, mites, and ticks. Several species of naturally occurring bacteria, fungi, nematodes, and viruses infect a variety of arthropod pests and play an important role in their management. Some entomopathogens are mass-produced in vitro (bacteria, fungi, and nematodes) or in vivo (nematodes and viruses) and sold commercially. In some cases, they are also produced on small scale for non-commercial local use. Using entomopathogens as biopesticides in pest management is called microbial control, which can be a critical part of integrated pest management (IPM) against several pests.
Some entomopathogens have been or are being used in a classical microbial control approach where exotic microorganisms are imported and released for managing invasive pests for long-term control. The release of exotic microorganisms is highly regulated and is done by government agencies only after extensive and rigorous tests. In contrast, commercially available entomopathogens are released through inundative application methods as biopesticides and are commonly used by farmers, government agencies, and homeowners. Understanding the mode of action, ecological adaptations, host range, and dynamics of pathogen-arthropod-plant interactions is essential for successfully utilizing entomopathogen-based biopesticides for pest management in agriculture, horticulture, orchard, landscape, turf grass, and urban environments.
Entomopathogen groups
Important entomopathogen groups and the modes of their infection process are described below.
Bacteria
There are spore-forming bacterial entomopathogens such as Bacillus spp., Paenibacillus spp., and Clostridium spp, and non-spore-forming ones that belong to the genera Pseudomonas, Serratia, Yersinia, Photorhabdus, and Xenorhabdus. Infection occurs when bacteria are ingested by susceptible insect hosts. Pseudomonas, Serratia and Yersinia are not registered in the USA for insect control.Several species of the soilborne bacteria, Bacillus and Paenibacillus are pathogenic to coleopteran, dipteran, and lepidopteran insects. Bacillus thuringiensis subsp. aizawai, Bt subsp. kurstaki, Bt subsp. israelensis, Bt subsp. sphaericus, and Bt subsp. tenebrionis are effectively used for controlling different groups of target insects. For example, Bt subsp. aizawai and Bt subsp. kurstaki are effective against caterpillars, Bt subsp. israelensis and Bt subsp. sphaericus target mosquito larvae, and Bt subsp. tenebrionis is effective against some coleopterans.
When Bt is ingested, alkaline conditions in the insect gut (pH 8-11) activate the toxic protein (delta-endotoxin) that attaches to the receptors sites in the midgut and creates pore in midgut cells. This leads to the loss of osmoregulation, midgut paralysis, and cell lysis. Contents of the gut leak into insect's body cavity (hemocoel) and the blood (hemolymph) leaks into the gut disrupting the pH balance. Bacteria that enter body cavity cause septicemia and eventual death of the host insect. Insects show different kinds of responses to Bt toxins depending on the crystal proteins (delta-endotoxin), receptor sites, production of other toxins (exotoxins), and requirement of spore. The type responses below are based on the susceptibility of caterpillars to Bt toxins.
Type I response – Midgut paralysis occurs within a few minutes after delta-endotoxin is ingested. Symptoms include cessation of feeding, increase in hemolymph pH, vomiting, diarrhea, and sluggishness. General paralysis and septicemia occur in 24-48 hours resulting in the death of the insect. Examples of insects that show Type I response include silkworm, tomato hornworm, and tobacco hornworm.
Type II response – Midgut paralysis occurs within a few minutes after the ingestion of delta-endotoxin, but there will be no general paralysis. Septicemia occurs within 24-72 hours. Examples include inchworms, alfalfa caterpillar, and cabbage butterfly.
Type III response – Midgut paralysis occurs after delta-endotoxin is ingested followed by cessation of feeding. Insect may move actively as there will be no general paralysis. Mortality occurs in 48-96 hours. Higher mortality occurs if spores are ingested. Insect examples include Mediterranean flour moth, corn earworm, gypsy moth, spruce budworm.
Type IV response – Insects are naturally resistant to infection and older instars are less susceptible than the younger ones. Midgut paralysis occurs after delta-endotoxin is ingested followed by cessation of feeding. Insect may move actively as there will be no general paralysis. Mortality occurs in 72-96 or more hours. Higher mortality occurs if spores are ingested. Cutworms and armyworms are examples for this category.
Unlike caterpillars, the response in mosquitoes is different where upon ingestion of Bt subsp. israelensis delta-endotoxin, the mosquito larva is killed within 20-30 min.
While Bt with its toxic proteins is very effective as a biopesticide against several pests, excessive use can lead to resistance development. Corn earworm, diamondback moth, and tobacco budworm are some of the insects that developed resistance to Bt toxins. Genetic engineering allowed genes that express Bt toxins to be inserted into plants such as corn, cotton, eggplant, potato, and soybean and reduced the need to spray pesticides. However, appropriate management strategies are necessary to reduce insect resistant to Bt toxins in transgenic plants.
Paenibacillus popilliae is commonly used against Japanese beetle larvae and known to cause the milky spore disease. Although Serratia is not registered for use in the USA, a species is registered for use against a pasture insect in New Zealand. In the case of Photorhabdus spp. and Xenorhabdus spp., which live in entomopathogenic nematodes symbiotically, bacteria gain entry into the insect host through nematodes. Biopesticides based on heat-killed Chromobacterium subtsugae and Burkholderia rinojensis are reported to have multiple modes of action and target mite and insect pests of different orders.
Fungi
Entomopathogenic fungi typically cause infection when spores come in contact with the arthropod host. Under ideal conditions of moderate temperatures and high relative humidity, fungal spores germinate and breach the insect cuticle through enzymatic degradation and mechanical pressure to gain entry into the insect body. Once inside the body, the fungi multiply, invade the insect tissues, emerge from the dead insect, and produce more spores. Natural epizootics of entomophthoralean fungi such as Entomophaga maimaiga (in gypsy moth), Entomophthora muscae (in flies), Neozygites fresenii (in aphids), N. floridana (in mites), and Pandora neoaphidis (in aphids) are known to cause significant reductions in host populations. Although these fastidious fungi are difficult to culture in artificial media and do not have the potential to be sold as biopesticides they are still important in natural control of some pest species. Hypoclealean fungi such as Beauveria bassiana, Isaria fumosorosea, Hirsutella thompsonii, Lecanicillium lecanii, Metarhizium acridum, M. anisopliae, and M. brunneum, on the other hand, are commercially sold as biopesticides in multiple formulations around the world. Fungal pathogens have a broad host range and are especially suitable for controlling pests that have piercing and sucking mouthparts because spores do not have to be ingested. However, entomopathogenic fungi are also effective against a variety of pests such as wireworms and borers that have chewing mouthparts.
Related to fungi, the spore-forming microsporidium, Paranosema (Nosema) locustae is a pathogen that has been used for controlling locusts, grasshoppers, and some crickets. When P. locustae is ingested, the midgut tissues become infected, followed by infection in the fat body tissues. The disease weakens and eventually kills the orthopteran host within a few weeks.
Various insects killed by different species of entomopathogenic fungi
Nematodes
Entomopathogenic nematodes are microscopic, soil-dwelling worms that are parasitic to insects. Several species of Heterorhabditis and Steinernema are available in multiple commercial formulations, primarily for managing soil insect pests. Infective juveniles of entomopathogenic nematodes actively seek out their hosts and enter through natural openings such as the mouth, spiracles, and anus or the intersegmental membrane. Once inside the host body, the nematodes release symbiotic bacteria that kill the host through bacterial septicemia. Heterorhabditis spp. carry Photorhabdus spp. bacteria and Steinernema spp. carry Xenorhabdus spp. bacteria. Phasmarhabditis hermaphrodita is also available for controlling slugs in Europe, but not in the USA.
Infective juvenile of Steinernema carpocapsae entering the first instar larva of a leafminer through its anus.
Nematodes in beet armyworm pupa (left) and termite worker (right).
Viruses
Similar to bacteria, entomopathogenic viruses need to be ingested by the insect host and therefore are ideal for controlling pests that have chewing mouthparts. Several lepidopteran pests are important hosts of baculoviruses including nucleopolyhedroviruses (NPV) and granuloviruses (GV). These related viruses have different types of occlusion bodies in which the virus particles (virions) are embedded. Virus particles invade the nucleus of the midgut, fat body or other tissue cells, compromising the integrity of the tissues and liquefying the cadavers. Before death, infected larvae climb higher in the plant canopy, which aids in the dissemination of virus particles from the cadavers to the lower parts of the canopy. This behavior aids in the spread of the virus to cause infection in healthy larvae. Viruses are very host specific and can cause significant reduction of host populations. Examples of some commercially available viruses include Helicoverpa zea single-enveloped nucleopolyhedrovirus (HzSNVP), Spodoptera exigua multi-enveloped nucleopolyhedrovirus (SeMNPV), and Cydia pomonella granulovirus (CpGV).
Most entomopathogens typically take 2-3 days to infect or kill their host except for viruses and P. locustae which take longer. Compared to viruses (highly host specific) and bacteria (moderately host specific), fungi generally have a broader host range and can infect both underground and aboveground pests. Because of the soil-dwelling nature, nematodes are more suitable for managing soil pests or those that have soil inhabiting life stages.
Biopesticides based on various entomopathogenic microorganisms and their target pests
Microbial control and Integrated Pest Management
There are several examples of entomopathogen-based biopesticides that have played a critical role in pest management. Significant reduction in tomato leaf miner, Tuta absoluta, numbers and associated yield loss was achieved by Bt formulations in Spain (Gonzalez-Cabrera et al, 2011). Bt formulations are also recommended for managing a variety of lepidopteran pests on blueberry, grape, and strawberry (Haviland, 2014; Zalom et al, 2014; Bolda and Bettiga, 2014; Varela et al, 2015).
Lecanicellium muscarium-based formulation reducedgreenhouse whitefly (Trialeurodes vaporariorum) populations by 76-96% in Mediterranean greenhouse tomato (Fargues et al, 2005). In other studies, B. bassiana applications resulted in a 93% control of twospotted spider mite (Tetranychus urticae) populations in greenhouse tomato (Chandler et al, 2005) and 60-86% control on different vegetables (Gatarayiha et al, 2010). The combination of B. bassiana and azadirachtin reduced rice root aphid (Rhopalosiphum rufiabdominale) and honeysuckle aphid (Hyadaphis foeniculi) populations by 62% in organic celery in California (Dara, 2015a). Chromobacterium subtsugae and B. rinojensis caused a 29 and 24% reduction, respectively, in the same study. IPM studies in California strawberries also demonstrated the potential of entomopathogenic fungi for managing the western tarnished plant bug (Lygus hesperus) and other insect pests (Dara, 2015b, 2016). Entomopathogenic fungi also have a positive effect on promoting drought tolerance or plant growth as seen in cabbage (Dara et al, 2016) and strawberry (Dara, 2013) and antagonizing plant pathogens (Dara et al, 2017)
Application of SeMNPV was as efficacious as methomyl and permithrin in reducing beet armyworms (S. exigua) in head lettuce in California (Gelernter et al, 1986). Several studies demonstrated PhopGV as an important tool for managing the potato tubermoth (Phthorimaea operculella) (Lacey and Kroschel, 2009).
The entomopathogenic nematode, S. feltiae,reduced raspberry crown borer (Pennisetia marginata) populations by 33-67% (Capinera et al, 1986). For managing the branch and twig borer (Melagus confertus) in California grapes, S. carpocapsae is one of the recommended options (Valera et al, 2015).
Entomopathogens can be important tools in IPM strategies in both organic and conventional production systems. Depending on the crop, pest, and environmental conditions, entomopathogens can be used alone or in combination with chemical, botanical pesticides or other entomopathogens.
Acknowledgements: Thanks to Dr. Harry Kaya for reviewing this article.
References
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The Value of Trees.
by Rainer Hoenicke, UC Master Gardener of Napa County As I looked east toward Atlas Peak...
Eastern hills of Napa County. (geologycafe.com)
Streets and houses all over town show evidence of thoughtful tree planting. (redfin.com)
Another Napa home with trees front and back. (rexhomes.com)
Trees have extensive root systems. (padredam.org)
What trees mean to a community. (belmontcitizensforum.org)
All this magic in the leaf of a tree. (britannica.com)
Tree roots depend on fungi. (ias4sure.com)
Kennedy Park stuffed with trees. (yelp.com)
Fuller Park, more trees. (napavalleyregister.com)
A new park in American Canyon with shade trees of the future. (napavalleyregister.com)
Just think of the value of redwoods and oaks--and all trees--to our well-being. (fineartamerica.com)
Napa Registry of Significant Trees