Factors restricting the feeding of the cabbage stem flea beetle (Psylliodes chrysocephala).
The feeding acceptability of 40 different plants (the majority belonging to Cruciferae, including turnips, Brussels sprouts and rape) to Psylliodes chrysocephala was determined using leaf disc consumption tests for the adult, and stem or petiole penetration tests for the larvae. Only plants that contained glucosinolates were accepted as food, but addition of the glucosinolate sinigrin to rejected food plants did not make them acceptable to adults. Of the 34 plants that contained glucosinolates, 9 were either totally or mostly rejected. Solvent extracts of the rejected plants (which included Pisum sativum, peas) applied to oilseed rape inhibited feeding by adults. It is concluded that the feeding of Psylliodes chrysocephala within the group of plants tested was influenced by the presence or absence of glucosinolates, which may act as phagostimulants, and other, unidentified chemicals which act as feeding inhibitors.