Bioactivity of seed extracts from different genotypes of Jatropha curcas (Euphorbiaceae) against Spodoptera frugiperda (Lepidoptera: Noctuidae)

Abstract

The armyworm Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae) is the main pest that attacks corn, and it has acquired resistance to chemical insecticides. In this study, the insecticidal and insectistatic activity of hexanic, acetonic, methanolic, and aqueous extracts of four genotypes of physic nut Jatropha curcas L. (Euphorbiaceae) seeds (Utim 1, Utim 2, Ahuehuetzingo, and Ceprobi) against S. frugiperda larvae was assessed. The acetonic extract at 5,000 ppm of the Utim 1 genotype, presented insectistatic activity by decreasing the weight gain of S. frugiperda larvae at 7 days by 66.7 % and at 14 days by 71.8 %, and prolonged larval development by 13 days, in addition to causing larval and pupal mortality of 72 and 84 %, respectively. The hexanic extract of Utim 2 showed insecticidal activity with a larval and pupal mortality of 80 % at 5,000 ppm. On the other hand, the acetonic extract of the Ahuehuetzingo genotype showed greater insecticidal activity at 5,000 ppm, with 100 % mortality of S. frugiperda larvae and pupae. The hexanic extract of the Ceprobi genotype presented insectistatic activity at 5,000 and 2,500 ppm, by reducing the weight gain of the larvae at 7 and 14 days by 47.6 and 74.3 % for 5,000 ppm and 28.5 and 53.0 % for 2,500 ppm. In addition, the acetonic and aqueous extracts at 5,000 ppm caused mortality of 76 and 80 % in S. frugiperda larvae and pupae, respectively. All concentrations of the Utim 2 and Ahuehuetzingo genotypes caused a phagostimulant effect on the feeding of insect pest larvae. J. curcas seed extracts can be explored as a useful alternative for the agroecological control of S. frugiperda.