THE INFLUENCE OF SALIX LEAF ABSCISSION ON LEAF-MINER SURVIVAL AND LIFE-HISTORY

1. Early abscission of mined leaves was an important mortality factor of a Phyllonorycter species (Lepidoptera: Gracillariidae) on Salix las iolepis Benth. (Salicaceae). A larger percentage of mined leaves absci sed early (34.4% in 1990; 24.5% in 1991), and Phyllonorycter survival was greatly reduced in these abscised leaves. 2. Leaf-mining by Phyllo norycter was associated with increased early leaf abscission. An egg r emoval experiment demonstrated that leaf mining induced this increase in leaf abscission. 3. The induction of early leaf abscission was depe ndent upon the timing of herbivory and simulated herbivory (mechanical damage). Early mechanical damage induced leaf abscission, late mechan ical damage did not. Mines which expanded early were more likely to in duce leaf abscission than mines which expanded more slowly.