Effects of phyllophaga (phytallus) hoegei larval density (coleoptera:melolonthidae) on plant and herbivore growth

Résumé 0

"The belowground herbivory has received relatively little attention. The plant response to belowground herbivory is variable and partially mediated by the identity and density of the root feeder. This study evaluated 1) the effects of belowground herbivory by two densities of the common root feeder, Phyllophaga (Phytalus) hoegei on the plant biomass, the nitrogen content of tillers and roots of the native, dominant grass Muhlenbergia quadridentata; and 2) the effects of these two larval densities on the survival and growth of this species. The experiment was performed in a pine forest area at 3200masl. Plants were established in pots in the field and subjected to belowground herbivory (three levels) in a completely random design with ten replicates per treatment. High densities of the root feeder significantly decreased root biomass and the root/shoot ratio, but the herbivores did not affect the nitrogen concentration of plant tissues. Survivorship of Phyllophaga hoegei larvae was not affected by growth density, but at high density the root feeder larvae decreased the relative growth rate and the weight gained."