The Phytophagous Insect Fauna of Milk Thistle In Southern California

Abstract

A diverse assemblage of phytophagous insects representing 6 orders, 24 families, and more than 47 species fed or reproduced on milk thistle, Silybum marianum (L.) Gaertner (Compositae), in southern California. Most of the insects attacking this introduced annual weed were polyphagous, ectophagous, sap- or foliage-feeding species; over half were economic species. Milk thistle apparently is relatively free of deleterious insect injury to its roots, stems, and reproductive parts in southern California. This preintroduction survey of its insect fauna provided reasonable assurance that species known to attack it in its native Europe were not already present, prior to undertaking additional surveys of its insect enemies and specificity studies of candidate biological control agents in the Mediterranean area.