To that end, the apparent correlation between the
feeding deterrent e!ect of several monoterpenoids and
their topical LD50 values in the tobacco cutworm
(Spodoptera litura) (Noctuidae) is noteworthy (Fig. 1, Isman,
unpublished data). Feeding deterrence was measured
in early 5th instar larvae (avg. wt."103 mg) using
a cabbage leaf disc choice bioassay (n"20) (Bomford
and Isman, 1996). Mortality was assessed following topical
administration (1 ll acetone carrier) to the dorsum of
3rd instar larvae (avg.wt."18 mg; n"250).