Effects of organic extracts of Bursera copallifera and B. lancifolia leaves in the development of Spodoptera frugiperda.
The genus Bursera has worldwide presence, some of its representative species are distributed in México, where are locally used as insecticides. Phytochemical studies of Bursera species have mentioned the presence of terpenoids, flavonoids and lignans. The plants extracts have been shown to possess a range of biological activities. Within the search of natural products with activity on insects, organic extracts (hexane, ethyl acetate and methanol) of Bursera copallifera and B. lancifolia leaves were tested for its effect on Spodoptera frugiperda development and acetylcholinesterase inhibitory activity. The extracts were analyzed by planar chromatography using reagents (anisaldehyde and natural products reagent) to detect specific groups of compounds. Neonate larvae of S. frugiperda were fed with insect diet mixed with extracts in a concentration of 1000 ppm. After seven days of the initial dosing, surviving larvae were weighed and its length measured. Administration of the hexane, ethyl acetate and methanol extracts from both species were correspondent with reduced larval weight and size. Insects treated with B. copallifera extracts were the most affected (73±0.005%, p<0.05 and 35±0.04% for weight and size reductions in ethyl acetate treatment). Acetylcholinesterase of S. frugiperda was inhibited in vitro to similar extent by methanol (IC50 367 µg mL-1) and ethyl acetate extracts (IC50 397 µg mL-1) from B. copallifera and B. lancifolia, respectively. Presence of terpenoids and flavonoids were confirmed after planar chromatography analysis. Results indicate that the extracts reduced larval growth and suggest that detected constituents may be partially responsible for the biological activity observed. Further studies on the physiological response when administered to insects and chemical characterization of the extracts are recommended.