Extraction solvents and geographical origins of Piper retrofractum on the control efficiency of Spodoptera litura and Spodoptera frugiperda in laboratory and greenhouse conditions

Typically, the active ingredients of plant extracts vary depending on the cultivation region and the solvent polarity. This research aimed to compare the control efficiency of the topical application of Piper retrofractum extracts from seventeen cultivar areas using two solvents, ethanol, and hexane on Spodoptera frugiperda and Spodoptera litura. Our study revealed that the hexane crude extract had the highest toxicity on both species (LC50 ∼ 2516 and 4325 ppm for S. frugiperda and S. litura, respectively). In addition, P. retrofractum from the northeastern area, especially from Bueng Kan Province, had the highest toxicity to S. frugiperda and S. litura (LD50∼38.38 and 58.38 ppm, respectively). The extract from this province also showed toxicity to both species, which was not different from that of synthetic pesticides in the greenhouse. The control efficiency of P. retrofractum extracts on S. frugiperda and S. litura depended on their cultivar areas and solvent polarity. These results will be useful as information for developing this plant as a botanical pesticide.