Dietary effects of non-nutrients in the leaf litter of forest trees on assimilation, growth and tissue composition of the detritivorous soil arthropod Anoplodesmus saussurei (Humb.) (Polydesmida: Diplopoda)

The possible ill effects of non-nutrient chemicals in leaf litter on detritivorous soil arthropods were evaluated using nutritional parameters (feeding, assimilation, respiration, growth) and body tissue composition (carbohydrates, glycogen, proteins, lipids) of Anoplodesmus saussurei (Humb.) (Polydesmida: Diplopoda), a commonly occurring yellow spotted flat back millipede. The animals were reared in microcosms on decomposing leaf litter of different forest trees. Colonization and preference for litter types, weight loss of litter due to feeding and apparent assimilation were highest in Cassia siamea followed by Dalbergia sissoo, Acacia auriculiformis and Shorea robusta in descending order. Chemical analysis of litter showed higher concentrations of non-nutrients, namely polyphenols and tannin, in Acacia and Shorea than in Cassia and Dalbergia litter. The dietary efficiency of A. saussurei decreased when reared on leaf litter treated with 0.1% solutions of synthetic grade phenol and tannic acid (sub-lethal dose, mortality < 10% in 7 days). The ill effect of feeding deterrents resulted in statistically significant decreases in the rate of assimilation (mg g−1 body weight day−1) and the growth rate (body weight and body length) of juveniles of A. saussurei. The impact was also evident from significantly low levels of tissue glycogen, lipids and carbohydrates in the animals reared on phenol and tannic acid treated litter. This detritivore, when exposed to the treated litter suffered from drastic decline in tissue calorific values and decreased rate of respiration. All the energy related parameters showed the advantage of C. siamea leaf litter, as a suitable dietary resource for this soil arthropod. Parameters such as preference, assimilation and growth rate and tissue composition in A. saussurei are potential indices of applied importance to assess the impact of litter quality on detritivore activity in afforested wasteland soil.