Earthworms are not only for the birds

To most people, the mere mention of worms is enough to make them shriek or curdle in fear and detestation.

Are all worms really that abominable?

Not so, if you know and believe in the science of soil biology, the study of living organisms in the soil.

Yes, the "good news" is that not all worms are "bad" like the ones in your rose garden (by the way, they are really caterpillars or larval forms of insects), the parasitic ones that probably infested you such as the bulate (a nematode) at an early stage of your life or the maggots (fly larvae) that scavenge on deal animals and dung.

This piece will be about the "good worms," particularly earthworms.

Before Charles Darwin, the "Father of Evolution," published his classic paper in l88l on "The Formation Vegetable Mould through the Action of Earthworms," earthworms were regarded as pests in the garden and were only good for the birds.

After studying the terrestrial annelids for 40 years, he concluded: "It may be doubted whether there are any other animals which have played so important a part in the history of the world as have these lowly organized creatures."

Even before Darwin, the great Greek philosopher Aristotle already recognized the important role that earthworms played in promoting soil fertility. He referred to them as "the intestines of the earth."

Today, it is established and well-acknowledged that the more than 4,000 earthworm species (we have over 400) in the world comprise the most important macrofauna in the soil.

They hasten the conversion of organic matter (mainly plant residues) into humus and improve soil structure and fertility.

The burrowing habit of earthworms also enhances water drainage and aeration of the soil.

By digesting organic matter, earthworms produce casts that contain slow release plant nutrients (nitrates and phosphates), increase the adsorptive capacity of the soil for minerals such as calcium, magnesium and potassium, increase the water-holding and buffer capacities of soils, support a more varied microbial population, and reduce the toxicity of natural and man-made substances, according to soil ecologists.

Vermicompost, the compost produced through the action of earthworms (e.g., Eisenia fetida and Eudrilus eugeniae), is better than thermophilic compost (produced through anaerobic decomposition) because it is fully stabilized (it won’t heat), has a granular texture and low C:N ratios, and contains plant growth regulators such as auxins, cytokinins and gibberellins, says Dr. Clive Edwards of Ohio State University who is considered the world’s leading authority on earthworms.

The application of vermicompost in the field at 2.5-l0 tons/ha has suppressed the parasitic nematode infestation of tomatoes, pepper, strawberries and grapes, reports Dr. Norman Arancon, a post-doctoral researcher of OSU.

In greenhouse studies, the use of vermicompost at 20 percent of potting mix significantly reduced insect damage of cabbage.

Vermimeal, processed earthworm biomass, is an excellent substitute for Peruvian fishmeal which is imported by developing and developed countries and used as an animal protein source for animal and fish feeds.

A recent study conducted in Negros Occidental, with the support of the Technology Incubation and Commercialization Program of the Department of Science and Technology, showed that with sugarcane tops and chicken manure as substrates for the "African nightcrawler," the vermimeal production of 5.5 g/day/sq.m is economically viable if the value of the resulting vermicompost as a by-product is accounted for.

Earthworms have been used in traditional Chinese medicine for more than 2,000 years.

Over 40 kinds of prescriptions for medicines from earthworms are known in the ancient medical journals of China.

It is claimed that such remedies have antipyretic, anesthetic, antihistamine, anti-hypertensive and anti-inflammatory properties.

In modern medicine, clinical trials are said to have been conducted in assessing the efficacy of recently discovered pharmaceuticals from earthworms such as an enzyme termed lumbrokinase that dissolves thrombi (blood clots) in the blood vessels of humans. An antibacterial peptide in the E. fetida and lectins in the E. eugeniae have also been found recently. In fact, there is a commercial product from China that is sold in local drugstores with the brand name "Plasmin." Marketed as a food supplement, it is said to contain natural enzymes from earthworms for dissolving blood clots.

There is an ongoing research collaboration between Drs. Clive Edwards and Norman Arancon of Ohio State University and this writer of the PCAMRD-DOST for studies on producing plant growth media, soil amendments, animal feed protein and pharmaceutical materials from animal wastes using innovative earthworm-based technologies with support from the United States Department of Agriculture.

The Philippines will host the International Symposium-Workshop on Vermi Technologies for Developing Countries to be held in Los Baños, Laguna on Nov. l6-l8.

Dubbed as ISWVT 2005, the meeting will bring together researchers and industry stakeholders from different regions of the world to assess the current status of vermicompost, vermimeal and vermiceutical technologies, and their prospects for developing countries.

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With all these and much more, can anyone still say that earthworms are only for the birds?

Dr. Rafael D. Guerrero III is executive director of the Philippine Council for Aquatic and Marine Research and Development of the Department of Science and Technology. He took his B.S. Zoology and M.S. Applied Zoology degrees from the University of the Philippines, and his Ph.D. in Fisheries Management from Auburn University, USA. His e-mail address is [email protected].