Earthworms are now highly regarded as a rich biological resource with a multitude of uses having commercial and environmental applications. This is evident as shown by the vigorous interest that people around the world have accorded on such technologies as vermicomposting, vermiculture, vermimeal production, vermiceutical production, and vermiremediation.
This is a development that is not unexpected considering that more than a century ago, English naturalist Charles Darwin made the following concluding statement in his last and final book : The plough is one of the most ancient and most valuable of man’s inventions; but long before he existed the land was in fact regularly ploughed by earth-worms. It may be doubted whether there are many other animals which have played so important a part in the history of the world, as have these lowly organized creatures (Darwin 1881).
This page reviews those uses. At the same time, this provides further enlightenment about earthworms by also putting into open their possible disadvantages and threats under the rule that where there is an advantage there is always a disadvantage.
One cannot just introduce a lovely plant that will turn later to be an invasive weed or any organism purported to be a rich source of nutritious food that will in time become a ravaging pest. Both crop and site selection are essential prerequisites to successful crop farming. In other words, research always precedes application.
For these worms to be promoted more efficiently, it must be totally understood. The one who does the promoting must be completely aware of the “two sides of a coin” of this creature. He or she must be prepared to answer questions, including the most discouraging ones or those asked simply to annoy.
Benefits and Uses of Earthworms
1. Having established their efficiency in converting organic substrates to composts, they are now widely used in vermicomposting for waste management, production of soil amendments, and other uses. The conversion of organic wastes into vermicompost started in the United States and United Kingdom in the 1980s (Guerrero 2009).
2. Whole or portions of the organism are traditionally used as fish bait. In the United States, their commercial production, or vermiculture, for fish bait was started in the 1950’s (Guerrero 2009).
3. These worms have been found to be an excellent source of animal feed protein, essential amino acids, fats, vitamins, and minerals for livestock and fish. Chemical analysis of the body tissues of earthworms showed the following composition: protein 60-70%, fat 7-10%, carbohydrate 8-20%, and minerals 2-3% (Edwards and Arancon 2006). It is recommended for processing into vermimeal, a dried and pulverized feed preparation. Studies on vermicomposting and vermimeal started in the Philippines in 1979 (Guerrero 2009).
They can be used in removing soil pollutants through bioremediation.
Heavy metals and other pollutants can be taken up by the worms and
removed from the soil, a process called vermiremediation (Edwards and Arancon 2006).
5. They can be processed into vermiceuticals, or pharmaceutical products, for the treatment of human diseases. There are many reports that these worms and body extracts have been used for the treatment of numerous human diseases in China and other Asian countries (Edwards and Arancon 2006). Studies conducted by Ang-Lopez and Alis (2006) revealed that earthworms are used as folkloric medicine in the Philippines. They also confirmed the anti-blood clotting action of a crude extract from mashed earthworms used by an indigenous group in Western Visayas to thin the blood in the elderlies. Back in 1986, an enzyme called lumbrokinase which dissolves blood clots in the human blood stream was isolated by a Japanese scientist. This breakthrough has been put into use through the manufacture and commercialization of dietary products (Guerrero 2006).
6. They can be processed into human food. They have been used as such by natives of Africa, South America, Japan, China, Papua New Guinea and New Zealand. In 1999, Guerrero and Martin reported that meatball dishes prepared from pure earthworm and 50% EWM and 50% pork were equally as palatable as pure pork (Guerrero n.d.). In the Philippines, a food supplement named Eugeton was developed from cultured African night crawler with the same anticoagulant properties as in imported products (Guerrero and Guerrero 2006).
Disadvantages and Threats
On the other hand, these annelid worms are not wholly beneficial. Darwin (1881) reported that they undermine large stones, pavements and buildings where the soil underneath is moist. When their burrows collapse, these stones and structures tilt and sink. Additionally, worm casts destroy the aesthetics in lawns and mossy landscape in bonsai, as well as deprive of sunlight the covered vegetation.
Various agricultural problems have also been reported which, according to James (2002), justify the promotion of knowledge of vermis in the Philippines. These include the destruction of the Banaue Rice Terraces in the Cordillera region by a giant species which was first detected in the early 1970s. These worms have eroded the terraces by burrowing into the walls and causing leaks. These were also found damaging the roots of germinated seeds (Marquez 2005). Belonging either to the genus Pheretima or Metaphire, these worms are considered non-native or invasive alien species (Joshi 2006).
Additionally, they can degrade rice fields due to soil perforation. According to Hairiah et al. (2001), “soil engineers” are not always welcome. In bunded rice fields, farmers reduce soil porosity by puddling and constructing dikes to contain the water. This effort is counteracted by the soil engineers which include the earthworms.
ANG-LOPEZ MJ, ALIS R. 2006. Indigenous use of earthworms for health in the Philippines. In: Guerrero RDIII, Guerrero-del Castillo MRA (eds.). Vermi Technologies for Developing Countries. Proceedings of the International Symposium-Workshop on Vermi Technologies for Developing Countries. Nov. 16-18, 2005, Los Baños, Laguna, Phils. Philippine Fisheries Association, Inc. p.135-144.
DARWIN C. 1881. The Formation of Vegetable Mould, Through the Action of Worms, With Observations of their Habits. London: John Murray. Retrieved May 27, 2011 from http://darwin-online.org.uk/pdf/1881_Worms_F1357.pdf.
EDWARDS CA, ARANCON NQ. 2006. The science of vermiculture: the use of earthworms in organic waste manangement. In: Guerrero R.D. III, Guerrero-del Castillo MRA (eds.). Vermi Technologies for Developing Countries. Proceedings of the International Symposium-Workshop on Vermi Technologies for Developing Countries. Nov. 16-18, 2005, Los Baños, Laguna, Philippines. Philippine Fisheries Association, Inc. p. 1-30.
GUERRERO RD III. 2009. Vermicompost and Vermimeal Production. MARID Agribusiness Technology Guide. 22 p.
GUERRERO RD III. n.d. The culture and use of earthworms as animal protein source in the Philippines. Philippine Council for Aquatic and Marine Resources and Development.
GUERRERO LA, GUERRERO RD III. 2006. Eugeton- a new natural health product from earthworms. In: Guerrero RDIII, Guerrero-del Castillo MRA (eds.). Vermi Technologies for Developing Countries. Proceedings of the International Symposium-Workshop on Vermi Technologies for Developing Countries. Nov. 16-18, 2005, Los Baños, Laguna, Phils. Philippine Fisheries Association, Inc. p. 145-147.
HAIRIAH K, WILLIAMS SE, BIGNELL D, SWIFT M, VAN NOORDWIJK M. 2001. Effects of land use change on belowground biodiversity. Retrieved June 30, 2011 from http://www.worldagroforestrycentre.org/sea/Products/Training/Materials/lecture%20notes/ASB-LecNotes/ASBLecNote%206A.pdf.
JOSHI RC. 2006. Invasive alien species (IAS): concerns and status in the Philippines. Retrieved June 30, 2011 from http://www.agnet.org/activities/sw/2006/589543823/paper-729213301.pdf.
MARQUEZ CD. 2005. Ridding Philippine rice terraces of rats and worms. Retrieved June 29, 2011 from http://www.scidev.net/en/south-east-asia/features/ridding-philippine-rice-terraces-of-rats-and-worms.html.
(Ben G. Bareja July 2011)