Osajin and Pomiferin, Two Isoflavones Purified from Osage Orange Fruits, Tested for Repellency to the Maize Weevil (Coleoptera: Curculionidae)

The fruit of the osage orange tree, Maclura pomifera (Raf.) Schneid (Moraceae), has long been thought to be repellent to insects. A preliminary study reported here confirmed repellency of fruit extracts to the maize weevil, Sitophilus zeamais Motschulsky. Two isoflavones, osajin and pomiferin, were isolated from the mature fruit of M. pomifera in high purity (≥95%). Testing of purified osajin and pomiferin failed to show repellency. Repellency is likely caused by factors other than isoflavones in the fruit.