Beauveria bassiana

Beauveria bassiana is an entomopathogene fungus of the family Clavicipitaceae. B. bassiana has many strains which display considerable distinctions in virulence, pathogenicity and specifity.

The action of B. bassiana on insects begins from the penetration of spores in a bode cavity through dermal coat (cuticle). Having penetrated in a body the spores germinate in hyphae, then a mycelium overgrows from which conidia split off. Having proved in the body the conidia begin to circulate in hemolymph. On this stage it is already possible the affection of insects by some strains in consequence of the excretion of the considerable quantity of toxins. If toxin is absent the mycelium gradually fills up the whole body of the insect. In the beginning muscular tissue is affected. Fungus growth continues until all the tissues are destroyed. The fungus can form conidiophores, which rupture the cuticle and the envelope of a dead larva. The affected insect is covered with white, wadded coating (conidiophores). Then it is observed spore maturation, and mass sporulation begins.

B. bassiana has the following properties:

  • affection takes place on different stages of insect ontogenesis;
  • the fungus possesses the high speed of growth and a huge reproductive ability;
  • it is able to remain for a long time in nature without the decline of entomopathogene activity;
  • the fungus has a high specifity (its virulence depends greatly on the strain of the fungus).

 

Nowadays B. bassiana is widely used as bioinsecticide for the pest control of agricultural, ornamental and forest plants. Biopesticides made on the base of B. bassiana are effective against various species of thrips and aphids, the glasshouse whitefly, larvae of Colorado beetle and also several species of leaf-gnawing pests.

Biopesticides are applied by way of the sprinkle of vegetative mass. The first signs of phytophage affection are observed in 5–7 days after treatment. Biopesticides can be applied singly or by means of mixture together with synthetic insecticides. But it is not recommended to use them simultaneously with fungicides. The minimal time interval of applications for fungicides is 48 hours before and after the treatment of B. bassiana biopesticides.

The effectiveness of this product depends very much on climatic conditions, the methods of application and doses. The best hydrothermal conditions for the development of B. bassiana are:

  • a temperature of 25–28°C;
  • a relative air humidity of 80–90%.

The treatments with B. bassiana pesticides are the most effective on the primary stages of phytophage development (preventively).

Usually B. bassiana pesticides are not toxic for useful insects, but it is known information about their negative influence on bees. Besides, Beauveria cannot be used in fish farming because it is potentially toxic for fish.

There are names of biopesticides containing Beauveria bassiana:

  • Naturalis
  • Botanigard
  • Mycotrol
  • Beauverin