Toxicities of host secondary compounds to eggs of theBrassica specialistDasineura brassicae.

The toxicities of selected host secondary plant substances to eggs of theBrassica specialistDasineura brassicae were estimated in a laboratory test. Isothiocyanates (ITCs) and 1-cyano-2-phenylethane, autolysis products of glucosinolates, were more toxic than a "green leaf alcohol,"cis-3-hexen-1-ol, found in numerous plant families. The most toxic compound, 2-phenylethyl ITC, occurs in all investigatedBrassica hosts ofD. brassicae. However, the less suitableBrassica hosts additionally release comparatively large amounts of allyl ITC. This suggests that even a crucifer specialist may be restricted in its use of particular hosts due to their compositions and concentrations of glucosinolate compounds.