Jpurnal of Chemical Ecology, Vol. 20, No.zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA 4, 1994 .ETHYL PROPIONATE: SYNERGISTIC KAIROMONE FOR AFRICAN PALM WEEVIL, Rhynchophorus phoenicis L. (COLEOPTERA: CURCULIONIDAE) GERHARD GRIES,I,* REGINE GRIES,I ALICE L. PEREZ,2 LILLIANA M. GONZALES,2 HAROLD D. PIERCE, JR.,2 A. CAMERON OEHLSCHLAGER,2 MARC RHAINDS,I MESMER ZEBEYOU, 3 and BROU KOUAME 3zyxwvutsrqponmlkjihgfedcba I Centre for Pest Management, Department of Biological Sciences 2Department of Chemistry Simon Fraser University Burnaby, Britisñ Columbia, Canada V5A 1S6 3/nstituts des Foréts (/DEFOR) Departement des Plantes Oléagineuses (DPO) Station Principale de La Me 13 B.P. 989 Abidjan 13, Cote d'Ivoire (Received August 17, 1993; accepted December 6, 1993) Abstract-Small trunk pieces of a freshly felled lO-year-old oil palm, Elaeis quineensis (Jacq.), were placed in a modified Nalgene desiccator, and volatiles captured for six days on Porapak Q. Gas chromatographic (GC) analysis of Porapak-Q-trapped volatiles with both f1ame ionization (FID) and electroan- tennographic detection (EAD) using male or female R. phoenicis antennae revealed several EAD-active compounds. They were identified as: ethyl ace- tate, ethyl propionate, isobutyl propionate, ethyl butyrate, and ethyl isobu- tyrate. In field experiments in the La Me Research Station, Cote d'Ivoire, ethyl propionate (50 mg/24 hr) but not all esters combined (50 mg/24 hr each) significantly increased capture of R. phoenicis in pheromone-baited (3 mg/24 hr) traps. One kilogram of 1- to 3-day-old palm tissue was significantly more effective than ethyl propionate in enhancing pheromone attraction. Superior attraction of palm tissue may be attributed to additional as yet unknown semi- ochemicals. Altematively, release rates and/or ratios of synthetic volatiles differed from those of palm tissue at peak attraction. Key Words-Coleoptera, Rhynchophorus phoenicis, Elaeis quineensis, kai- romone, synergism, oil palm, palm weevil, palm volatiles, host selection, *To whom correspondence should be addressed. 889 0098-0331/94/0400-0889$07.00/0 © 1994 Plenum Publishing Corporation