Factors Affecting Leaf Litter Decomposition by Micropterna sequax (Trichoptera: Limnephilidae)

Abstract

Feeding behaviour and consumption rates of the caddisfly Micropterna sequax (Trichoptera: Limnephilidae) larvae were investigated under laboratory conditions. The consumption rates of M. sequax were measured at four temperatures (5.5, 9.5, 13 and 19 degrees C) and its feeding preferences among four leaf species (European beech, oak, chestnut and oriental plane) were studied. Furthermore, fresh and senescent conditioned or not beech leaves were offered to Micropterna larvae to assess the impact of the leaf age and conditioning on the larvae feeding rates. Temperature exerted a pronounced effect on the consumption rates of the larvae, the optimum temperature for feeding being 13 degrees C. In all the experiments, larvae showed a sound preference for chestnut leaves over the other leaves tested, with consumption rates of up to 0.55 mg leaf mg(-1) animal d(-1). Senescent beech leaves were clearly preferred against fresh ones, while no significant differences were recorded between the consumption rates of conditioned and non-conditioned plant material. The role of physical and chemical characteristics of the leaves possibly involved in the larvae selectivity is also discussed.