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Allylglucosinolate, found in many cruciferous plants, is acutely toxic to Papilio polyxenes larvae, which do not normally attack crucifers. By contrast, larval growth of Pieris rapae, a crucifer specialist, is not affected even by artificially high concentrations of allylglucosinolate. Larval growth of Spodoptera eridania, a generalist feeder, is inhibited by high but not by low concentrations of the compound.
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Blau et al. (1978) studied this question.
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