A Test of Plant-Vigor, Plant-Stress, and Plant-Genotype Effects on Leaf-Miner Oviposition and Performance

Phyllonorycter sp. (Lepidoptera : Gracillariidae) preferentially oviposited on leaves of vigorous potted and wild Salix lasiolepis Benth. (Salicaceae) host plants. A given unit of leaf area on a vigorous potted host plant was also more likely to be oviposited on, but this was not true of vigorous wild plants. These pattems of host use increased Phyllonoryster survival by reducing mortality associated with premature abscission of Salix leaves and shoots. An in situ common garden experiment demonstrated that Phyllonorycter densities and performance were not influenced by the clonal identity of potted host plants. Drought treatment of potted plants reduced shoot lengths and xylem water potential, but did not influence Phyllonorycter density.