Abstract
Evidence from many sources indicates that the rate of decomposition can be related to the chemical-physical characteristics of the leaves, such as their thickness and C and N content. Whereas some data indicates that Collembola show clear feeding preferences, little is known about the substances responsible for Collembola feeding preferences. In this paper preliminary data on the avoidance behaviour of Sinella coeca towards isoprene, an important secondary plant metabolite, are reported. The animals demonstrated a clear avoidance reaction even at concentrations of 10-1 μM; despite isoprene volatility, observations made over two consecutive days demonstrated that the clustering of specimens on the food without isoprene persisted over time, probably in relation to the release of aggregation pheromones that stabilize the initial choice. The evident avoidance behaviour shown by Sinella coeca warrants further studies in order to describe the defensive potential of isoprene to a broad spectrum of herbivores. The possibility that isoprene may affect litter decomposition rates is discussed.