Beauveria bassiana

Biocontrol Agent

Beauveria bassiana is a contact mycoinsecticide (an insecticide which contains fungi) that is registered for use in the United States on a wide range of pest insects and can be used on many agricultural and horticultural crops.

Common Names

None

Relative effectiveness

Products containing B. bassiana are most effective when used proactively and targeting younger insect larvae usually results in better insect control. Repeat applications may be necessary if insect populations are high. Signs of adequate control can take 6 – 14 days to appear. Efficacy may be variable, but proper application timings and conditions will increase effectiveness (see Maximizing effectiveness for more details).

Where to use

Formulations of B. bassiana can be used in controlled environments (e.g., greenhouses, shade houses, and nurseries) and outdoors on labeled crops and plants such as turf, fruits, vegetables, and more.

Any time you use a pesticide, you must read and follow the label directions and comply with all applicable laws and regulations related to pesticide use. Also be sure that any pesticide used is approved for use in your country and state/province.

About Beauveria bassiana

Beauveria bassiana is a contact mycoinsecticide (an insecticide which contains fungi) that is registered for use in the United States on a wide range of pest insects and can be used on many agricultural and horticultural crops. The effectiveness of B. bassiana is variable depending on application environment and conditions. Beauveria bassiana is a naturally occurring organism in the soil throughout the world. Learn more

  • Native/Non-native: Native

  • Preferred climate: Humid • temperate • Mediterranean • sub-tropical

Beauveria bassiana Appearance

The spores of B. bassiana may be formulated in different ways for commercial sale (e.g., as suspensions or powders). The fungal growth on infected insects is a dense, white powder. Depending on the environmental conditions, sporulation – the process where the fungi produce reproductive structures, called spores or conidia – may or may not be visible on the surface of insects that are killed by the fungus. 

Beauveria bassiana life cycle

Spores are produced on a previously-infected insect. Alternatively, they may be purchased as a bioinsecticide.

The aerial conidia (spores) are spread by wind, rain or insect movement. They attach themselves to a suitable host (e.g., an insect) after contact.

The spores germinate and penetrate the insect. The fungus begins to grow vegetatively.

After producing toxins (in purple) and exploiting the nutrients within the mummified cadaver of the host, the fungus will transition to reproductive growth.

The fungus grows out of the insect, where it produces more spores to be spread into the environment.

How to Use Beauveria bassiana

Biocontrol category: Augmentative – must be released/applied repeatedly 

When to use: Because the spores of B. bassiana can be impacted by exposure to UV light, it is best to apply this biological control agent in the late afternoon or evening, or on cloudy or rainy days.

Rate: Application rates vary depending on the pest and crop. Always follow the instructions on the label when applying this biopesticide. 

Maximizing effectiveness: To make the application of B. bassiana most effective, applications should be undertaken when the humidity is high, when the UV light is low (late afternoon or cloudy/rainy days), and at warm temperatures 64° – 85°F (18° - 29°C). 

Manufacturers sometimes offer additional useful tips for applying their products most effectively.  

Pest stages attacked by Beauveria bassiana: 

  • larvae—beetles, caterpillars

  • adults—aphids, thrips, whiteflies, chinch bugs, plant bugs, stink bugs, beetles

Mode of action: This product works as a parasite of insect pests. The fungi attach to the cuticle (shell/skin) of the insect and breaks it down with enzymes. Once it can enter the hemolymph (the insect blood stream), it rapidly takes over the inside of the host and uses it for nutrients. See infection process section for more information.

Conservation: Fungicides usually should not be applied at the same time or close to the application of products containing B. bassiana [2,3]. Always read the label before applying pesticides. 

Compatibility: A summary of the compatibility of B. bassiana with other types of pesticides. Note: Make sure to evaluate compatibility with other pesticides or tank additions on a small number of plants prior to large applications. Always read and follow the product label when applying these products.

  • Sometimes compatible (product dependent)
    • Acaricides
    • Adjuvants
  • Usually not compatible (check label for specific application intervals)
    • Fungicides
  • Generally compatible
    • Herbicides
    • Insecticides
    • Other biopesticides

Risk: The label of a pesticide containing B. bassiana will have specific information about potential risks to people and the environment. In general, products containing B. bassiana may cause eye irritation and can be harmful if inhaled, swallowed, or absorbed through the skin. Potentially harmful to beneficial insects and honeybees – do not apply to areas where pollinators are actively foraging. May be toxic to fish – do not discharge rinsate into bodies of water or public waterways or apply this product over standing water or near aquatic habitats. See Effects on non-target organisms section for more information on the safety of B. bassiana to non-target organisms.

Commercially available: B. bassiana is available commercially in the United States in a variety of products and formulations and is labeled for many common lawn and garden pests. You must read and follow the label and all applicable laws in your state/province when applying this product. 

Pests Targeted by Beauveria bassiana

Beauveria bassiana targets a wide range of pests across most insect orders and is known to infect over 700 species of insects [1]. B. bassiana is not registered for use on earthworms, slugs, or snails.

A white grub sits curled in a “C” position on the top of rocky soil. The immature insect has a red/brown head followed by three sets of legs immediately behind it. The rest of the body is a white or cream to gray color and is opaque but covered in fine hairs.

White grubs are one of many pests that can be targeted with this biocontrol agent. They are the larvae of Scarab beetles (Phyllophaga spp.).

Small, long black insects on the yellow petals of a coreopsis flower

Thrips are one of many insect pests that can be targeted with products containing Beauveria bassiana

Learn more about Beauveria bassiana

The entomopathogenic fungus, Beauveria bassiana (order Hypocreales: family Clavicipitaceae), is a well-known and widely studied fungal insect pathogen. It was discovered in 1835 by an Italian entomologist named Agostino Bassi after it was found infecting and killing large numbers of silkworms [1]. It is known to have a wide host range and can infect over 700 species of insects [2]. B. bassiana has a cosmopolitan distribution in the soil, so it is found naturally throughout the world [3]. In addition to being a generalist insect pathogen, it can also be a saprobe - feeding on decaying matter in the soil - and an endophyte, meaning it lives without symptoms of disease within plant tissues [5]. Additionally, B. bassiana has been shown to increase plant defenses to abiotic stresses [6], as well as to biotic stresses such as insect herbivory [7], in addition to promoting plant growth. It can also be antagonistic to plant pathogens such as Rhizoctonia solani and Pythium myriotylum [8]. A more comprehensive review of B. bassiana and its use in integrated pest management can be found by reading Dannon et al. [9]. 

Infection process of Beauveria bassiana

Beauveria bassiana spores start the infection process once they contact the insect cuticle (Figure 1). After contact is made, the fungus begins to produce enzymes (e.g., lipases, chitinases, proteases, etc.) to break down the cuticle layers, then the spores germinate and form germ tubes and appressoria, which are responsible for holding the spores to the insect and exert mechanical pressure on the cuticle [10]. Once the germ tubes (now called hyphae) reach the hemolymph (blood) of the insect, they begin to form specialized single-celled spores (blastospores) to exploit the nutrient rich environment of the insect blood, colonize the tissues, and produce toxic metabolites that kill the insect [11]. Insect death is caused by starvation as the fungus takes over the internal structures of the insect, which finally results in outward penetration of the cuticle and sporulation on the mummified body of the host [12].

Effects on non-target organisms 

Beauveria bassiana is known to have a wide host range and can infect soil-dwelling and foliar insect pests. Because of its ability to persist in the soil and infect many different insects, there could be competitive effects between introduced strains of B. bassiana and native microbes, or potential non-target effects on beneficial insects. However, the physiological host range (e.g., the host range that can be infected in the lab) and the ecological host range (e.g., the hosts that are infected under natural or field conditions), can vary greatly between fungal strains [13]. For a more comprehensive review of the safety of B. bassiana, including a table of results from susceptibility studies of beneficial and non-target insects, please see Zimmerman [3].  

Effects on non-target beneficial insects 

Although it has been shown in laboratory studies that B. bassiana can potentially be harmful to beneficial insects like lady beetles and bees, very few field studies have shown this same trend. The table below summarizes the effects of B. bassiana on non-target organisms in laboratory and field studies (Table 1; modified from Zimmerman [3];). Vestergaard et al. [14] reports that evidence from field studies does not suggest frequent adverse effects of B. bassiana on non-target insects and other invertebrates. 

Effects on non-target soil microorganisms 

Wang et al. [15] showed that B. bassiana strains did not outcompete or displace native fungal strains in the field, and Castrillo et al. [16] reports that genetic recombination between introduced and native strains is rare because of the large number of vegetative compatibility groups. When screened against common soil microarthropods such as mites and collembolans, there were no detrimental effects on either group (summarized in Zimmerman 2007), and it has been reported that these soil microarthropods can be valuable dispersal methods for entomopathogenic fungi [17, 18].  

Effects on non-target Vertebrates (excluding mammals) 

Beauveria bassiana appears to pose minimal risks to vertebrates. According to Zimmermann [3] (and references within), birds are generally not affected after consuming B. bassiana spores. Goettel & Jaronski [19] reported that spores (strain GHA) did not affect the embryos or larvae of flathead minnows, and that the product Naturalis-L ® did not affect the development of embryos, larvae, or adults of rainbow trout. However, the inland silverside fish did show adverse developmental effects when exposed to B. bassiana spores [20]. No mortality or infection was observed when spores were fed to leopard frogs [21], although captive American alligators and tortoises have shown mortality from infections by B. bassiana [22, 23]. However, it should be considered that captive animals tend to be under temperature stress, which can lead to increased susceptibility to fungal diseases at lower temperatures. 

Effects on non-target Mammals 

Like with most fungi in the environment, immunocompromised individuals could be at greater risk of fungal infections and should take care when handling products containing fungal spores. Agricultural workers or those involved in the production of B. bassiana products should take care to safeguard themselves from exposure to spores by wearing proper personal protective equipment like gloves, protective eyewear, or respirators as required by product labels. Some of the potential health hazards to humans include allergic reactions of the respiratory tract [24] and skin and eye irritation. In laboratory studies where rats were inoculated with B. bassiana, no infectivity or pathogenicity of the fungus was observed [24]. However, there have been some reported cases of mycotic keratitis (infection of the cornea in the eye) in humans, and the patients recovered successfully after treatment with proper medications [25]. Products containing B. bassiana are evaluated by the U.S. Environmental Protection Agency (EPA) for health and safety concerns and using these products according to the label will reduce risks to people and the environment. You can view the EPA evaluation for strain GHA here: Beauveria bassiana Strain GHA (128924) Technical Document (pdf). For more examples of B. bassiana infections in mammals, see Zimmermann [3].  

Summary of non-target effects of B. bassiana products in field studies

Beneficial organismCommon nameResults/ObservationsLab/Field Trials (L/F)
Amblyseius cucumerisCucumeris mite (predator)No detrimental effect when sprayed onto excised cucumber leavesL/F
Apis melliferaEuropean honey bee (pollinator)Conidia were applied in bee hives: low mortality and no noticeable effect on behavior, larvae and colony characteristicsF
Arthropod and nematode populationsChlorpyrifos had a stronger negative impact than the microbial treatmentF
Bembidion lampros Agonum dorsaleGround beetlesA negligible number was infected; low susceptibility of both speciesF/L
Bombus terrestrisBuff-tailed bumblebee (pollinator)Able to infect bumblebees; it appears that there are no risks if the fungus is incorporated into soil or sprayed onto plants that are not attractive to bumblebeesL/F
Carabidae: StaphylinidaeInfection levels in adult ground beetles and rove beetles were low (Carabidae max. 7.6% and Staphylinidae max. 7.0%); an epizootic in the staphylinid Anotylus rugosus (67%) and Gyrohypnus angustatus (37%) was observedF
Cephalonomia tarsalisParasitoid wasps3 h exposure to 100 and 500 mg kg-1 wheat resulted in 52.5 and 68.6% mortality-
Coleomegilla maculataSpotted or Twelve-spotted ladybeetle (predator)No mortality was observedL/F
Lysiphlebus testaceipes‚ Aphidius colemaniParasitoid waspsNo significant impacts on both parasitoidsF
Nontarget arthropods (major predators, parasitoids and pollinators on rangeland)No statistical differences in the abundance of aerial insectsF
Nontarget arthropods (forests)From 3615 invertebrates collected, only 2.8% became infected; B. bassiana could be applied to forest soil without a significant negative impact on forest-dwelling invertebrate populationF
Non-target beetle communitiesNo detectable effectsF
Orius insidiosusInsidious flower bug (predator)Can be usedF
A. colemani‚ Dacnusa sibiricaParasitoid waspsNot recommended during application of B. bassiana
Encarsia formosa, Eretmocerus eremicus‚ Aphidoletes aphidimyzaParasitoid wasps, Aphid midge (predator)Used with caution during application of B. bassiana

Effectiveness of B. bassiana

There are many factors that contribute to the effectiveness of products containing B. bassiana, including UV light intensity, humidity, temperature, insect life stage, and fungal strain  virulence [3, 12]. Humidity and temperature are both very important factors for fungal survival and germination, where warmer temperatures and higher humidity usually lead to increased survival and germination [26]. Exposure to UV light is also an important factor in the effectiveness of B. bassiana. Inglis et al. [27] found that spore survival was significantly reduced after just 15 minutes of direct exposure to UV-B radiation. Additionally, the species of insect that is targeted can impact how quickly insect death and fungal sporulation occurs. Zimmermann [3] reports that the incubation period of the fungus in some insects can be as short as 3 - 4 days, while in others might take 2 - 4 weeks (for aphids and white grub larvae, respectively).  

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Author

Morgan Swoboda
Department of Entomology, Cornell University

Date: June 10, 2022

Thank you to the Extension and Outreach Assistantship in the Cornell Department of Entomology for funding this project. Thank you to the Soil Arthropod Ecology Lab for reviewing and giving feedback on early versions of the article. 

  • [1] M. R. De Faria and S. P. Wraight, “Mycoinsecticides and mycoacaricides: A comprehensive list with worldwide coverage and international classification of formulation types,” 2007, Accessed: Jan. 14, 2021. [Online]. Available: https://www-sciencedirect-com.proxy.library.cornell.edu/science/article/pii/S1049964407001843?via%3Dihub

  • [2] K. K. Khun, G. J. Ash, M. M. Stevens, R. K. Huwer, and B. A. Wilson, “Compatibility of Metarhizium anisopliae and Beauveria bassiana with insecticides and fungicides used in macadamia production in Australia,” Pest Management Science, vol. 77, no. 2, pp. 709–718, Feb. 2021, doi: 10.1002/ps.6065.

  • [3] F. A. Celar and K. Kos, “Effects of selected herbicides and fungicides on growth, sporulation and conidial germination of entomopathogenic fungus Beauveria bassiana,” Pest Management Science, vol. 72, no. 11, pp. 2110–2117, 2016, doi: 10.1002/ps.4240.

  • Infection process of entomopathogenic fungi. Figure credit: Morgan Swoboda (created in BioRender.com)
  • A spotted lanternfly infected with the spores of B. bassiana. Photo credit: Eric Clifton, BioWorks Inc.
Morgan Swoboda

PhD Student

Department of Entomology

Morgan Swoboda
  • mhs338 [at] cornell.edu
Portrait of Amara Dunn
Amara Dunn-Silver

Senior Extension Associate

NYS Integrated Pest Management

Amara Dunn-Silver