Worm Research on Eudrilus Eugeniae Extracts on Certain Plant Pathogens

Worm research studies are posted here regarding various aspects of university level, laboratory-tested benefits of earthworms and amazing qualities of their manure known as castings.

By S.V. Shobha¹ and Radha D. Kale²
1.Mount Carmel College, Department of Environmental Science, 58 Vasanthanagar, Bangalore 560 052, India

2.University of Agricultural Sciences, Department of Zoology, GKVK Campus, Bangalore 560 065, India

January 2008

Summary:

"The aim of the study was to find out the effect of aqueous earthworm extracts (body wall extract, gut extract and coelomic fluid) of the earthworm Eudrilus eugeniae on selected soil-borne plant pathogens using simple laboratory techniques.

Though many researchers have reported the suppression of diseases on application of worm compost and compost tea there has been no worm research carried out on using earthworm and its secretions directly as antimicrobial agents.

When a mixed extract was used to test the effect on F.oxysporum, very interestingly (a) strong zone of inhibition was obtained, indicating that a combination of extracts will have a better effect on fungal pathogens rather than individual extracts.

Since earthworms are soil residents and they play an active role in improving soil quality, it was hypothesized that worm extracts may have inhibitory/suppressive effect on soil-borne pathogens. Hence 3 bacterial and 5 fungal soil-borne plant pathogens were selected for the study.

The result showed that the body wall and gut extract had both antibacterial and antifungal activities while coelomic fluid (of the earthworm) was found to have only antibacterial activity.

Body wall and gut extracts were found to have inhibitory effect on the following:

Xanthomonas campestris (pathogen which attacks cabbage,broccoli and other brassicae members),
Ralstonia solanacearum ( organism which causes brown rot of potato, bacterial wilt or southern wilt of tomato, tobacco, eggplant, and some ornamentals, and Moko disease of banana).
Fusarium oxysporum (pathogenic fungus causing a variety of plant diseases, including cabbage yellows and wilt of tomato, flax, cotton, peas, and muskmelon).
Erwinia carotovora ( bacteria which cause plant tissues to become soft and watery which eventually turn slimy and foul-smelling) inhibited by gut extract and coelomic fluid.
Botryodiplodia theobromae, soil-borne fungal plant pathogen, was suppressed by body wall extract, but at slightly higher concentrations.

This worm research seems to validate the reason why vermicompost is so very successful in fungal disease suppression. The earthworms present in the soil release coelomic fluid from the dorsal pores, the body wall which is in direct contact with the soil and the excreta from the gut of the worm, all act together and result in antimicrobial activity thus suppressing several soil-borne plant diseases." (Highlighted for emphasis)