New study uncovers earthworm feeding habits and microbial activity in vermicomposting

Prof N Irabanta Singh *

A recent publication in the OPEN ACCESS JOURNAL OF MICROBIOLOGY & BIOTECHNOLOGY (OAJMB), Medwin Publishers, USA, vol. 9(3): 000304 (published date August 27, 2024).Professor N. Irabanta Singh and his student, Dr. K. Babyshila Devi explores groundbreaking insights into the field of microbiology.

In a groundbreaking study from Manipur University's Life Sciences Department, researchers have unveiled new insights into the feeding behaviors of two widely used earthworm species, Perionyx excavatus and Eudrilus eugeniae, and their pivotal role in the vermicomposting process.

The three-year investigation sheds light on how these earthworms break down organic wastes, particularly cow dung and vegetable wastes from university’s kitchen and the microbial changes that occur within their guts and in the resulting vermicompost.

Feeding Behavior Insights

The study discovered that Perionyx excavatus requires about three hours to fill its gut, while Eudrilus eugeniae takes slightly longer, at three and a half hours. This difference results in P. excavatus completing eight gut fillings per day, compared to seven for E. eugeniae.

The research highlights the remarkable efficiency of these earthworms in processing organic wastes, with P. excavatus consuming 9.7 mg (dry mass) of cow dung per hour and E. eugeniae consuming 20.96 mg per hour.

Microbial Findings

Beyond feeding habits, the researchers also examined the bacteria present in the earthworms' guts and the vermicompost they produced. Several bacterial species were identified in the gut content, including Bacillus sp., Klebsiella sp., Micrococcus sp., and Proteus sp.

Notably, Micrococcus sp. was found exclusively in the gut of P. excavatus and was absent in the vermicompost, while Proteus sp. was only detected in the gut of E. eugeniae.

The persistence of Bacillus and Klebsiella species in the vermicompost suggests that these bacteria are not digested during the earthworm’s gut passage, potentially due to their production of antibiotics or resilient outer coats, allowing them to survive the decomposition process.

Impact on Vermiculture

These findings underscore the significance of understanding earthworm feeding biology for optimizing vermiculture practices. Both Perionyx excavatusand Eudrilus eugeniae have demonstrated their effectiveness as vermicomposting agents, playing a crucial role in converting organic wastes into valuable plant nutrients.

The study also highlights the influence of environmental factors, particularly temperature, on the survival and growth of these earthworm species. P. excavatus showed a greater tolerance to high temperatures compared to E. eugeniae, making it more adaptable to varying environmental conditions.

In conclusion, this research provides valuable insights for enhancing vermicomposting efficiency and underscores the essential role of earthworms in sustainable waste management.