Role of Paecilomyces lilacinus in biological control of plant parasitic Nematodes”

MORPHOLOGY OF PAECILOMYCES LILACINUS:

            The fungus is lilac to purple colored soil hyphomycete. Produce smooth to rough conidia endogenously from small groups of unclumped phialides borne on conidiophores. Vegetative hyphae are branched and septate (Esser and Gholl, 1993).

HABITAT:

          Paecilomyces lilacinus occurs naturally in soil, in egg clusters contained in the gelatinous egg mass of root knot nematodes, and in cyst of Globodera spp. and Heterodera spp. ( Esser  and  Gholl, 1993).

                          

    Fig.1- Pure culture of Paecilomyces lilacinus.

Fig. 2- Microscopic image of P. lilacinus conidia, conidiophores and philides.

Fig. 3 - A root knot nematode female with its egg mass infected with Paecilomyce lilacinus .

MODE OF ACTION OF PAECILOMYCES LILACINUS:

1. Vegetative hyphae enter the gelatinous matrix of root-knot nematode.
2. Hyphae grow into the open cyst neck of cyst nematodes.
3. Once inside, hyphae form branches and grow across egg shell surfaces.
4. Hyphal tips swell, forming an appressorium on the egg surface.
5.  A penetration peg forms below the appressorium and grows into the egg shell.
6. Penetrated eggs swell and buckle.
7. As penetration continues, the vitelline layer of the egg splits into three   bands,
8. Numerous vacuoles appear, and the lipid layer almost disappears.
9. Hyphae fill the egg, and then emerge to the egg surface producing first vegetative growth and then conidiophores and conidia.

10.  After five days, most of the eggs in the mass are infected.

11.  Juveniles in eggs may become infected when such eggs are invaded by the fungus.

12.   Adult females become infected when hyphae enter the vulva or anus.

REDUCTION DUE TO PAECILOMYCES LILACINUS ON PLANT PARASITIC NEMATODES:

Egg hatch, numbers of root galls, no of egg masses, Giant cell formation in host plant tissue is inhibited. 

MAJOR  ADVANTAGES  DUE  TO  PAECILOMYCES  LILACINUS  :

1. Target specific.
2.  Easy to apply 
3.  Eco-friendly.
4.  Cost effective.
5.  Effective for long period
6.  Easily available
7.  Enhance  the plant growth
8.  Important component of IDM.

SEMI – SELECTIVE MEDIA FOR PAECILOMYCES LILACINUS (Mitchell et al, 1987):

          The fungus multiplied well in all the media. Rapid growth was observed in semi selective medium. The fungus took about 28-30 days at 28±1°C to cover the entire flask in all the media. Highest fungal biomass (19.82 g) and spore load (32.8X107 spores/g) was observed in semi selective medium. Molasses 10% medium yielded moderately high biomass and spore production (16.85g and 28.8 X10⁷ spores/g respectively),10% molasses medium is a cheaper substrate for mass multiplication.

DOSES AND METHODS OF APPLICATION:

Soil application:  

          Mix 200 gm. of active ingredient with 1 kg of compost and store in a shade for a week. During early morning or evening apply this mixture in the root region in a sq. m. area and water it.

Main field:

          Mix 2 - 6 Kg. of active ingredient with 200 kg. of farm yard manure and store in a shade for a week. During early morning or evening apply this mixture in the root region in a acre area and water it.

Bare root dip treatment:

             Roots of seedling are dipped into the suspension of fungus and after that seedlings are used for transplanting. Along this fungus we can also used other chemicals, which are used for seed treatment in combination.

LIMITATIONS OF PAECILOMYCES LILACINUS:

    1.   Isolates of P. lilacinus differ widely in virulence and ability to become established in soil.

    2.   The fungus lacks an effective aggressive trapping mechanism which severely limits its potential.

    3.   Require high soil temperature.

CONCLUSION:

                   From the foregoing discussion, it can be concluded that Paecilomyces lilacinus is an important egg parasitic fungus, mostly associated with the eggs of root knot and cyst nematodes.

REFERENCES:

Anwar, S. A. and M. V. McKenry, 2012. Incidence and Population Density of Plant  Parasitic Nematodes Infecting Vegetables Crops and Associated Yield  Losses in Punjab. Indian Journal of Zoology., vol.44 (2),pp – 327-333.

Jonathan, E. I. and Rajendran, G., 2000. Biocontrol potential of the parasitic fungus Paecilomyces lilacinus against the root knot nematode Meloidogyne incognita in banana. Journal of Biological Control, 14 (2): 67-69.

Article compiled by Mr. Amol Vijay Shitole (Ph.D. Scholar)

Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola (M.S.)