Because cucurbitacins have been considered critical factors in host selection by adapted diabroticite beetles, reduction of the cucurbitacin content of cultivated cucurbits has been suggested for management of diabroticite pests through antixenosis. Although in laboratory and field choice tests, diabroticites have been shown to prefer plants that are rich in cucurbitacin, the effectiveness of antixenosis in pure stands is uncertain.
We tested the degree to which cucurbitacin explains patterns of field colonization and aggregation by one important diabroticite pest, Acalymma vittatum [F.], the striped cucumber beetle. In relatively large replicated field plots, we planted near-isogenic lines of cucumber, differing only in the presence or absence of cucurbitacin. Demonstration of preference for cucurbitacin by A. vittatum is dependent on factors such as previous sequestration, scale, and mating behavior. At a distance of 30 m, overall damage was only marginally higher in plots planted with cucurbitacin-rich cucumbers than cucurbitacin-free cucumbers. Local induction of cucurbitacin was not correlated with an increased degree of aggregation for A. vittatum.
Species 1: Coleoptera Chrysomelidae Acalymma vittatum (striped cucumber beetle)
Keywords: antixenosis, diabroticite
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