C-2-6

SEASONAL AND POPULATION VARIATION IN THE FLAVONOIDCONTENT OF ALLIARIA PETIOLATA AFFECTING PIERIS NAPI OLERACEA

Meena Haribal and J. Alan A. Renwick
Boyce Thompson Institute, Tower Road, Ithaca, NY 14853, USA



Pieris napi oleracea, an indigenous butterfly to North Americalays eggs on Alliaria petiolata, an invasive weed introduced fromEurope, but the larvae showed considerable variation in development ondifferent sources of the plant. A. petiolata is a compulsivebiennial. A. petiolata foliage is rich in apigenin flavonoids.We compared the chemistry of different vegetative forms from differentpopulations in the vicinity of Ithaca NY. throughout the year. There weresignificant differences in number of apigenin derivatives in differentpopulations and forms. A significant variation in the amount of these compoundsin different seasons also was found. We have isolated two major compoundswhich affect development of P. napi oleracea larvae.Comparison of these compounds in two populations throughout out the yearalso showed that maxima occurred twice annually. They are almost devoidof flavonoids around June-July. Thus variation in the chemistry of theplant can account for the variation seen in the development of the larvae. Several apigenin compounds were also isolated and identified by extensiveNMR studies.