Population regulation of the native holly leafminer, Phytomyza ilicicola Loew (Diptera: Agromyzidae), on American holly

摘要: Three sources of mortality, intraspecific competition, parasitism, and early leaf abscission, were investigated to determine their importance in regulating populations the leafminer Phytomyza ilicicola Loew (Diptera: Agromyzidae) on cultivated American holly trees. Spatial aggregation leafminers among leaves resulted density-dependent mortality from interference competition for nutritional resources. Pupal weight survivors decreased significantly as within-leaf density increased. Within-tree parasitism P. by Opius striativentris (Hymenoptera: Braconidae) ranged 3%–58%, but was independent host both individual a tree-wide spatial scale. The incidence abscission higher mined than unmined leaves, with about 14% abscising before adult emerged. There high O. within fallen leaves. These results are discussed relation recent hypotheses concerning role population regulation leafminers.