Growth Inhibitory Effects on Fall Armyworm Spodoptera frugiperda of Some Limonoids Isolated from Cedrela spp. (Meliaceae)

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Abstract
Dichloromethane extracts of Cedrela salvadorensis and Cedrela dugessi afforded a photogedunin epimeric mixture, gedunin and cedrelanolide. These compounds and the photogedunin epimeric acetates 3 and 4 at the 23-OH position were evaluated against Spodoptera frugiperda. Toosendanin, isolated from Melia azedarach, was used as a positive control. When tested for activity on neonate larvae into the no-choice bioassays, gedunin, photogedunin epimeric mixture, and photogedunin acetates mixture caused significant larval mortality with LC50 of 39.0, 10.0, and 8.0 ppm at 7 days, respectively, as well as growth reduction. All the compounds tested inhibited larval growth, compared to the control, in a concentration-dependent manner. In addition, it was possible to observe significant reduced pupal weights and adult emergence. All the tested compounds except cedrelanolide showed comparable activity to that of toosendanin. Keywords: Cedrela salvadorensis; C. dugessi, Meliaceae; Spodoptera frugiperda; Lepidopterae; limonoids; photogedunin; gedunin; cedrelanolide; toosendanin; insect growth inhibitors