Cucurbitacin contents and diabroticite (Coleoptera: Chrysomelidae) feeding upon Cucurbita spp.

Eighteen species of Cucurbita were examined qualitatively for spectrum of cucurbitacins present and quantitatively for the amounts in leaves, fruits, and roots by means of thin-layer chromatography, mass spectrometry, and ultraviolet absorption spectrometry. Crumpled leaves and sliced fruits of the various species were exposed to large populations of the southern cornrootworm (SCR), Diabrotica undecimpunctata howardi Barber, and the western cornrootworm (WCR), D. virgifera LeConte. There was a strong correlation between the total cucurbitacin content and the extent of aggregation and feeding by both SCR and WCR.