The fecundity and the vermicomposting efficiency of three generations of four earthworm species in high-rate vermireactors fed with the pernicious aquatic weed salvinia

Abstract

With vermireactors designed on the basis of the concept of high-rate vermicomposting recently introduced by S.A. Abbasi and co-workers, it has become possible to directly vermicompost phytomass, including pernicious weeds. It has also been shown that upon vermicomposting, even toxic and allelopathic weeds get transformed into highly plant-friendly and soil-friendly organic fertilizers. Pre-existing vemireactors were not able to achieve direct vermicomposting of weeds or other plant biomass, for reasons explained in the main text. But it is necessary to ascertain whether vermireactors can be operated indefinitely with problematic weeds and whether earthworms born in such vermireactors have adequate health and reproductive ability to sustain the vermireactors interminably. Hence the present work has been undertaken to assess the performance of three successive generations of four earthworm species in terms of their ability to vermicompost the highly ligninous aquatic weed salvinia and reproduce in the vermireactors solely fed by it. It was seen that in all cases the first generation of animals, which had been born and grown to adulthood in cow-dung fed vermiculture systems, took time to adapt to the weed-feed, but did so and remained healthy. The next generation which was born and raised in salvinia-fed vermireactor was significantly more efficient in vermicomposting salvinia while the third generation was still more efficient in comparison to the second generation. The trend of third generation being superior to the second and the second being superior to the first was manifest in the production of offspring (juveniles and cocoons) as well. All-in-all the findings, covering 16 months of uninterrupted vermireactor operation, reveal that earthworms tend to get acclimated to have salvinia as their exclusive feed and the successive generations of earthworms that are born and grown in the weed-feed reactors manifest not only greater vermicomposting efficiency but also superior reproductive ability than the earthworms which had been raised on animal manure.

Keywords: Drawidawillsi; Eisenia andrei; Lumbricus rubillus; Peryonix sansibaricus; Salvinia; Vermicomposting.