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Beauveria Bassiana - A Pyrethrum Synergist

November 11, 2019

  • Beauveria Bassiana
  • Pyrethrum Synergists

Beauveria Bassiana

B. bassiana strain GHA is a fungus that can be used as a pesticide for controlling many kinds of insects. There are many different strains of beauveria bassiana and they can be found in soil. Since b. Bassiana can be found so abundantly in the soil, this particular fungus is more effective targeting foliar pests rather than soil pests. Typically, they work by growing on the outsides of insects and secrete enzymes to weaken their body and get inside to start growing inside their insect host. This fungus does not need to be ingested by its host and it eventually leads to the insect’s death. Upon death, the spores cover the carcass in a layer of white mold that produces even more infective spores to infect more pests. Residues of the pesticide are not expected to remain on treated plants. Beauveria Bassiana is not expected to have adverse effects on people or the environment. Pesticide products containing this main ingredient that are approved for both commercial and residential cannabis production include: Botanigard Maxx and Xpectro OD both by the LAM International Corporation which are essentially the same product containing Pyrethrins at 0.75% and beauveria bassiana strain GHA at 0.60%. Since beauveria bassiana is mixed with Pyrethrum in approved pesticides, both of their limitations should be noted. Even though both are not toxic to mammals, birds, plants, or the environment in general, there is still potential for these products to be harmful to bees in outdoor environments. Beauveria bassiana alone is commonly used in commercial agriculture to target adults and larvae of whiteflies, aphids, and grasshoppers but when mixed with Pyrethrum it can also be effective against thrips and spider mites.

Grasshoppers killed by b. bassiana

Image of B. Bassiana fungus infecting grasshoppers (4).
Pyrethrum Synergists

Synergists are chemicals mixed with insecticides (commonly pyrethrum-based products) that make insecticidal ingredients more effective (3). They usually have a low impact on insects alone, but when used in combination with certain pesticides, the resulting mixture is more effective. Some of the pest populations can possibly break down Pyrethrins and recover from their initial paralysis, but synergists can interrupt the pest’s recovery, and make the insecticide more toxic to the target pests. Synergists can also increase the rate of mortality in insecticide-resistant pests as well. The interaction between the GHA strain and natural botanical pyrethrins is synergistic, with multiple modes of action and pest control results comparable to more toxic chemical pesticides. In research studies conducted to determine the effectiveness of b. Bassiana as a stand-alone pesticide or as a synergist with pyrethrins and results show that b. Bassiana has a higher mortality rate as a synergist than as a stand-alone pesticide.


  1. (2019). “Pesticide Use in Cannabis Production Information”. Colorado Department of Agriculture.

  2. Wu S, et al. (2017). “Synergistic Combinations of a Pyrethroid Insecticide and an Emulsifiable Oil Formulation of Beauveria bassiana to Overcome Insecticide Resistance in Listronotus maculicollis (Coleoptera: Curculionidae)”. Department of Entomology, Rutgers University. J Econ Entomol. 2017 Aug 1;110(4):1794-1802. doi: 10.1093/jee/tox176.

  3. (2016). “What Are Synergists?”. Oregon State University. National Pesticide Information Center.

  4. (2006). “Grasshoppers killed by the fungus Beauveria Bassiana”. Wikimedia Commons.

  5. (2000). “Beauveria Bassiana Strain GHA Technical Document”. United States Environmental Protection Agency.

  6. (n.d.). “Xprectro”. LAM International.

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