Effects of glucosinolates on a generalist and specialist leaf-chewing herbivore and an associated parasitoid

► Effects of glucosinolates on herbivores and parasitoids. ► Negative correlation of glucosinolates with performance of a generalist herbivore. ► Similar result with a specialist herbivore, despite detoxification mechanism. ► Positive correlation with parasitoid performance, perhaps due to host immune system. ► Our study documents a dual defensive role of glucosinolates.