Dear Sri Anuampady,
As our forum member, I am trying to answer your questions.
The nature of earth warms is dwelling in the soils, eat the organic matter available, leaving its excreta and after the organic matter is exhausted , start searching its food at other places and moving in and around by crawling. In this process Aeration/Oxygen is required. This is stated by several Universities/Agri-Horti Institutes.
Here, we have to understand that the nature of Earth warms, either Desi and/or Videsi, is to do like, as stated above, upto the gathered information from Universites/Agri-Horti Institutes. Here I have to tell you that, if any research is done on earth warms and its result is stated by any , we can take it to our consideration and we accept. i opine that , If some one says, It is Desi Eath Warm or Videsi Earth Warm, It may not be out of place to mention here that it may not be taken in to consideration, as it does not have any proof from any Universites/Agri-Horti Institutes. This is my personal opinion.
Agriculture is on the earth from considerable old times and several experts, both Qualified/Experienced, stated several farming systems and several farmers are following some system, basing on their requirement/feasibility to their conditions. They are correct in some and may be wrong in some.
Here to tell you, In my experience, I have observed that any earth warm will dwell in the soils and crawl for search of food only. Differance may be there in their size, crawling in to depths and ups, in eating the food quantities only. No much differance in Desi and videshi and all are lives and organic only and none are poisonous.
Earth Warms do well in Red and Gravel soils, better than other soils , provided , organic matters like leafy compost, well conditioned FYMs etc, should present in ithe soils. Up to my gathered information from Authorities, reveals that Earth Warms needs Aeration/oxygen to live and Organic matter to eat. Think twice, if your soil is Black, clay and with out much organic matter, and also pure Sandy soils, to do farming in organic way/Natural Farming, as earth warms may not do/like to their operations.
The above is my gathered information and my opinion.
with best wishes, g.p.rao, farmer