RESUMEN
Field tests of corn co-expressing two new delta-endotoxins from Bacillus thuringiensis (Bt) have demonstrated protection from root damage by western corn rootworm (Diabrotica virgifera virgifera LeConte). The level of protection exceeds that provided by chemical insecticides. In the bacterium, these proteins form crystals during the sporulation phase of the growth cycle, are encoded by a single operon, and have molecular masses of 14 kDa and 44 kDa. Corn rootworm larvae fed on corn roots expressing the proteins showed histopathological symptoms in the midgut epithelium.
Asunto(s)
Bacillus thuringiensis/química , Proteínas Bacterianas/farmacología , Toxinas Bacterianas , Endotoxinas/farmacología , Control de Insectos/métodos , Zea mays/metabolismo , Animales , Toxinas de Bacillus thuringiensis , Electroforesis en Gel de Poliacrilamida , Proteínas Hemolisinas , Inmunidad Innata , Immunoblotting , Larva , Modelos Genéticos , Plantas Modificadas Genéticamente , Transformación GenéticaRESUMEN
A phagostimulant, 6,10,14-trimethylpentadecan-1-one (phytone), was isolated and identified from Bermuda grass,Cynodon dactylon (L.). The phagostimulant activity of this isoprenoid ketone was established from bioassays of fall armyworm larvae,Spodoptera frugiperda (J.E. Smith). Larvae displayed increased body mass accumulation as well as preference to diet supplemented with this molecule. Neonate larvae fed diet supplemented with chromatographic isolates of phytone-containing fractions from six Bermuda grass cultivars showed a 10-40% increase in body mass accumulation as compared with controls. This variation in larval body mass accumulation seems attributable to a differential concentration of phytone in the cultivars, which ranged from 0.5 to 43 ppm. Additionally, first-instar larvae responded preferentially to diet pellets topically treated with phytone in concentrations as low as 0.1 ppm.