Acid stress in Rumex hydrolapathum (Polygonaceae) and its influence on the phytophage Lycaena dispar (Lepidoptera; Lycaenidae).

The relationship of insect growth to host condition was tested on host plants grown by hydroculture with a standard nutrient solution, but under different acidities, ranging from pH 3.5-7.5. The indirect effect of the host on the development of the phytophage was tested in the pupal stage. The host plant Rumex hydrolapathum had its highest nitrogen content in the range pH 5.5-6.5; pupal weight of Lycaena dispar was correlated with nitrogen concentration, ash weight and water content. There is a remarkable difference in element concentration between young and old leaves of the host, which varies with acidity of the rooting substrate.In this experiment a negative relationship was detected between reproduction of the phytophage and stress of the host.