Growth inhibitory effects on fall armyworm Spodoptera frugiperda of some limonoids isolated from Cedrela spp. (Meliaceae)

Dichloromethane extracts of Cedrela salvadorensis and Cedrela dugessi affor ded a photogedunin epimeric mixture, gedunin and cedrelanolide. These compo unds and the photogedunin epimeric acetates 3 and 4 at the 23-OH position w ere evaluated against Spodoptera frugiperda. Toosendanin, isolated from Mel ia azedarach, was used as a positive control. When tested for activity on n eonate larvae into the no-choice bioassays, gedunin, photogedunin epimeric mixture, and photogedunin acetates mixture caused significant larval mortal ity with LC50 Of 39.0, 10.0, and 8.0 ppm at 7 days, respectively, as well a s growth reduction. All the compounds tested inhibited larval growth, compa red to the control, in a concentration-dependent manner. In addition, it wa s possible to observe significant reduced pupal weights and adult emergence . All the tested compounds except cedrelanolide showed comparable activity to that of toosendanin.