Chemical modification produces species-specific changes in cucurbitacin antifeedant effect

LANG K. L.; DEAGOSTO E.; ZIMMERMANN L. A.; ROCHA MACHADO V.; CAMPOS BERNARDES L. S.; SCHENKEL E. P.; DURAN F. J.; PALERMO J. A.; ROSSINI C.

JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY

AMER CHEMICAL SOC

Lugar: Washington; Año: 2013 vol. 61 p. 5534 - 5539

0021-8561

Cucurbitacins are secondary metabolites that mediate insect plant interactions not only as allomones against generalists, but also as kairomones for specialist herbivores. This study was undertaken to identify the potential of cucurbitacin derivatives as insect antifeedant agents. The antifeedant capacity against a Cucurbitaceae specialist [Epilachna paenulata (Coleoptera: Coccinellidae)] and a polyphagous insect [(Pseudaletia adultera (Lepidoptera: Noctuidae)] was evaluated in preference tests in which the insects were given a choice between food plant either treated with the cucurbitacin derivatives or treated with the solvent. The activity was found not to be related to the basic cucurbitacin skeleton as only 16 of the 30 tested cucurbitacin derivatives were active. Only one of the tested compounds was phagostimulant to the specialist insect (the hemissuccinate of 16-oxo-dihydrocucurbitacin B derivative), while all other active derivatives were deterrent against one of the insects (13 compounds, 81%) or both of them (3 compounds, 19%). Changes in ring A of the cucurbitacins, as well in the side chain modified the activity. As a general trend, when chemical modifications of the basic structure produced a change in activity, response was opposite in both insects used as biodetectors, indicating that a selective variation in the activity may be achieved by chemical modifications of the cucurbitacin skeleton.