Substances that alter insect behavior have attracted a lot of attention as potential crop protection agents. Naringenin (5,7,4'-trihydroxyflavanone) is a naturally occurring bioactive flavanone. We evaluated the influence of naringenin on aphid activities during individual phases of probing and feeding and the effect of structural modifications of naringenin on its activity towards aphids. We monitored the probing behavior of Myzus persicae (Sulz.) (Hemiptera: Aphididae) using the Electrical Penetration Graph (EPG) technique. The chemical modifications were the substitution of hydrogen atoms with methyl, ethyl or pentyl groups and the replacement of the carbonyl group in naringenin and its derivatives with an oxime moiety. Depending on the substituents, the activity of naringenin-derived compounds varied in potency and mode of action. Naringenin was an attractant of moderate activity, which enhanced sap ingestion. The naringenin derivative with two methyl groups-7,4'-di-O-methylnaringenin-was a deterrent, which hindered aphid probing in non-phloem tissues. Naringenin oxime derivatives with methyl substituents-7,4'-di-O-methylnaringenin oxime, 7-O-methylnaringenin oxime, and 5,7,4'-tri-O-methylnaringenin oxime-and the derivative with a pentyl substituent-7-O-pentylnaringenin oxime-were strong attractants which stimulated aphid probing in non-phloem tissues and the ingestion of phloem sap.
Keywords: antifeedants; attractants; electrical penetration graph; peach potato aphid; structure-activity relationships.