Lipid, polyamide, and flavonol phagostimulants for adult western corn rootworm from sunflower (Helianthus annuus L.) pollen

Adult Diabroticites including western corn rootworm (WCR), Diabrotica virgi fera virgifera LeConte, consume pollen of corn, squash, sunflower, and othe r species. Short-chain neutral amino acids in methanol-water extracts of po llen have been previously identified in our laboratory as strong phagostimu lants for Diabrotica. Bioassay-driven fractionation was used to characteriz e the interacting lipid and midpolarity phagostimulants for adult WCR in Gi ant Gray Stripe sunflower, Helianthus annuus L., pollen. Lipids rich in ome ga 3-linolenic acid including triglycerides, free fatty acids, phosphatidyl ethanolamines, phosphatidic acids, and phosphatidylcholines were highly pha gostimulatory. Other important phagostimulatory components included a hydro xycinnamic acid-polyamine amide, N-1,N-5,N-10-tri[(E)-p-coumaroyl]spermidin e and a flavonol, quercetin beta-3-O-glucoside. The structural characterist ics of these phagoactive compounds and their role in the pollinivory specia lization of rootworm beetles are discussed.