Solid state fermentation technology of Beauveria Bassiana
- Part 2 -

KC Puzari / Pranab Dutta / LK Hazarika *

FUNGUS

Freshly isolated Beauveriabassiana infected dead cadavers are to be isolated in potato dextrose agar medium

CULTURAL AND MICROSCOPICAL CHARACTERISTICS OF THE FUNGUS
CULTURAL CHARACTERISTICS

Colonies are milky white and moderately rapid growing, spreading woolly, powdery or mealy in texture, white to yellowish white or occasionally pinkish in colour.

MICROSCOPICAL CHARACTERISTIC

The entomopathogenic fungus Beauveriabassiana produces at least three distinct single-cell propagules, aerial conidia, vegetative cells termed blastospores, and submerged conidia, which can be isolated from agar plates, from rich broth liquid cultures, and under nutrient limitation conditions in submerged cultures, respectively.

Conidiogenous cells are hyaline, flask shaped with long zig-zig appearing rachis beraing lateral conidia. Conidia are hyaline, 1-celled and globose to ovoid with a length about 3.5µm. Clusters of condiogenous cells appear as small powdery balls in the aerial hyphae when viewed through a dissecting microscope.

* To harvest large quantity of propagules, the isolate are to be mass cultured in polypropylene bags containing sterilized (autoclaved at 121oC for 20 min. repeated for 2 successive days) in rice hull : saw dust : rice bran medium @25 : 25 : 100 respectively supplemented with 2% dextrose.

* Polypropylene bags each having capacity of 150 g containing 50 g medium are to be inoculated with 1ml of 1 X 107 conidia ml-1 suspension and incubated at 24 + 1oC for 20 days.
* To obtain uniform growth of the fungus, the bags were mechanically shaked thoroughly after 5 days.
* After 21 days of incubation the bags were kept in racks at room temperature and ready for application.

PREPARATION OF SPORE/CONIDIAL SUSPENSION OF B.BASSIANA

* The conidial density as obtained from the mass cultured medium (RH:SD: RB) is 39.33 x 107 conidia ml-1 of water.
* A conidial concentration 1 x 107 conidia ml-1 of water have to be used for spraying by suspending 1000 g of mass cultured substrate with homogenous fungal growth in 5000 ml of water.
* Prior to spray the mixture has to be filtered through single layered muslin cloth to prevent the nozzle block.

METHOD OF APPLICATION

The prepared spore/conidial suspension (as per the method mentioned above) of B.bassiana can be applied with the help of Knapsack sprayer in the morning hours at least 2 hrs prior to sun rise or in the evening at least 1 hrs after the sunset. In rainy days Tween 80 or Teepol or toilet/bath soap @ 0.02% should be mixed in the spore suspension prior to the spraying.

AAU STRAINS IS EFFECTIVE AGAINST FOLLOWING INSECT PESTS

* Rice hispa, Decldes-paarmigera
* Tea mosquito Bug, Helopeltistheivora
* White fly, Bemisia-tabaci;
* Grasshoppers, Heiro-glyphusbanian
* Colorado potato beetle, Leptinotarsadecemlineata
* Cabbage caterpillar, Pierisbrassicae
* Stem borer, Scripo-phegaincertulas
* Aphid, Aphis gossypii
* Banana scaring beetle, Nodostomasubcostatum
* Aphid, Aphisgosypii, N.Virescens
* BPH, N. lugens

ADVANTAGES

o Microbial insecticides based on B.bassiana are non-toxic and nonpathogenic to wild life, humans and other organisms not closely relate to the target pest.
o They are specific to a single group or species of insects not affecting the predators and parasites of the pest.
o They are compatible with the chemical insecticides i.e. not deactivated or damaged by chemical insecticides.
o They can be used when the crop is ready to harvest as the residues have no hazard to human or other animals.
o They may establish themselves in a pest population or its habitat and provide controls to subsequent pest generations.
o Resistance development to microbial pathogens is also slow. They can control insect in cavities, where chemical insecticides cannot reach.

DISADVANTAGES

o Each application of microbial controls only a portion of the pests but the rests continues to damage in the treated areas
o Heat, desiccation or exposure to UV rays and long storage reduces the effectiveness of microbials. As they are pest specific, their potential sales market is limited.
o Some of the products of microbial are not widely available and are relatively expensive

PRECAUTIONS

o Select freshly isolated virulent pure culture.
o B.bassiana must be passed through host as much as possible for higher infection percentage.
o Avoid using contaminated culture for mass culturing and field application.
o Spraying must done before sunrise or after sun set.
o Spraying equipment must be free from any other chemical pesticides
o In rainy days sticker must be used.
o Avoid spraying other pesticides in the B.bassiana applied field.

For further details contact:
Public Relations & Media Management Cell,
CAU, Imphal.
Email: [email protected]

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