INTENSITY OF LONGITARSUS-JACOBAEAE HERBIVORY AND MORTALITY OF SENECIO-JACOBAEA

1. Aspects of population biology of Longitarsus jacobaeae, in relation to the biocontrol of Senecio jacobaea were studied in a coastal dune area in the Netherlands. 2. No influence of adult herbivory on S. jacobaea mortality in winter was found, plant size was most important in this respect. 3. Mortality of S. jacobaea in spring was considerable where larval herbivory by L. jacobaeae was intense. 4. Larval and adult herbivory were most intense in subpopulations in the open area of the dunes. 5. Adult herbivory was proportional to plant size, but in densely vegetated areas larger plants, and in less vegetated areas smaller plants, were attacked relatively more frequently.