Leaf litter preference and conversion by a saprophagous tropical pill millipede, Arthrosphaera magna Attems

Microcosm experiments were carried out to assess the palatability, litter consumption, growth and food conversion efficiency of pill millipede Arthrosphaera magna. Among the five diets assessed, millipedes preferred conditioned leaf litter over fresh leaf litter in 24 h feeding trial. Highest litter ingestion was seen in areca followed by banana, Acacia and cashew. Ingestion and faecal pellets production was highest on mixed litter in 3 days and 10 days feeding trials. Coconut was the most preferred single litter in both trials, however, its consumption and faecal pellet production was higher in 10 days than in 3 days trial. Weight of faecal pellets of millipedes fed with mixed litter outweighed monolitter feeds. Among the monolitter diets, coconut ranked first in faecal pellet production. Total weight of faecal pellets produced on 10 days trial on six kinds of diets significantly differed (P=1.66×10-9, one-way ANOVA). Significant difference was also seen in mass of faecal pellet between mixed litter and coconut litter diets (P=0.029, paired t-test). Except for coconut litter, the rest showed higher organic matter in litter than in faecal pellets. Faecal pellets produced on all litter diets showed higher calcium than litter. Similarly, faecal pellets produced on banana, cashew and mixed litter diets showed higher magnesium than other diets. On monolitter diets offered for ten days, ingestion rate, weight and number of faecal pellets were highest between 2 and 4 days, subsequently, all except for coconut litter, steep decline was seen in these parameters and attained almost lowest profile on the 10th day. However, on coconut litter diet, ingestion and faecal pellet production were high, but declined gradually. On mixed litter diet, rate of consumption, mass and number of faecal pellets were high on the first day and more or less it was constant and never declined as in monolitter diets. On comparison, the rate of food ingestion of mixed litter by A. magna was several folds higher than temperate and other tropical millipedes (561.1-598.2 vs. 1.02-157 mg/animal/day), so also the faecal pellet production (550-570 vs. 0.97-126.05 mg/animal/day). The nutrients of mixed litter might fulfill the nourishment for growth, maturity and reproduction of A. magna. Food conversion efficiency of A. magna was higher on mixed litter than monolitter diets in our study, justifying distribution and abundance of Arthrosphaera spp. in mixed forests of the Western Ghats of India.