Olfactory Responses of Diabrotica spp. (Coleoptera: Chrysomelidae) to Cut Fruits of Bitter and Nonbitter Cucurbita spp.1

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Abstract
Laboratory tests indicated that adult diabrotica virgifera virgifera LeConte had the same olfactory response to the cut fruits of four Cucurbita species: the bitter C texana Gray; and C. andreana Naud. and their respective nonbitter relatives C pepo L. and C. maxima Ouch. Field tests indicated that there were no significant differences in the numbers of adult Diabrotica spp. captured on sticky traps baited with the cut fruits of C. texana or C. pepo, or on an unbaited control. We concluded that the cut fruits of C. texana and C. andreana were not more attractive to adult diabrotica spp. than were the cut fruits of C. pepo and C. maxima. Since C. texana and C. andreana contain large quantities of cucurbitacins and C. pepo and C. maxima do not, we must also conclude that cucurbitacins in these bitter fruits did not act as Diabrotica attractants. The preference of diabrotica spp. to choose bitter over non bitter Cucurbita spp. as aggregation sites is not due to a differential olfactory response to the cut fruits, per se.