Olfactory and behavioral responses of red imported fire ants, Solenopsis invicta, to ylang ylang oil and its components

Abstract

The red imported fire ant, Solenopsis invicta Buren, is one of the most successful invasive pest ants in the world. We evaluated ylang ylang oil, an essential oil of fragrant yellow flowers of the tree, Cananga odorata, in our effort to search for attractants and repellants for S. invicta management. The results showed that ylang ylang oil elicited clear dose dependent EAG (electroantennography) responses to ants of all castes. We performed EAG on 70 chromatographic fractions from ylang ylang oil. To facilitate the identification of active compounds in each fraction, the fractions which covered strong EAG activity shift were subjected to gas chromatography-mass spectrometry analysis, revealing that S. invicta exhibited strong olfactory responses to fractions dominated by terpenes or esters. Further EAG analysis showed that prenyl acetate (PA) and benzyl acetate (BA) were key compounds responsible for high EAG amplitude in male alates. In addition, ylang ylang oil, PA and BA were attractive to male and female alates in two-choice attraction bioassay and they also act as attractants at low concentrations to workers in two-choice digging bioassay. Discovery of these behavior-modifying compounds may open up new possibilities for developing better fire ant control products by manipulating chemosensory communication of ants.