Journal of Chemical Ecology, VoL 8, No. 8, 1982 IMPROVED PREPARATION OF (E)-/3-FARNESENE AND ITS ACTIVITY WITH ECONOMICALLY IMPORTANT APHIDS G.W. DAWSON, D.C. GRIFFITHS, J.A. PICKETT, M.C. SMITH, and CHRISTINE M. WOODCOCK Rothamsted Experimental Station Harpenden, Herts., AL5, 2JQ, U.K. (Received November 10, 1981;revisedJanuary 4, 1982) Abstract--(E)-/3-Farnesene,the majorcomponent ofthe alarmpheromone of many aphids, is prepared in 65% yieldby passingcommercial nerolidol through an evacuatedcolumnof alumina,treated withpyridine,at 200~ The product is stored without air and applied to aphids as vapor at low speed (ca. 230 ram/see) in air or nitrogen. The response of eight economically important aphid specieswas assessedin the laboratory; over 90% of Myzus persicae responded in a large scale trial. Key Words~Aphids, Myzus persicae, Homoptera,Aphidae, pheromone, alarm pheromone, behavior, (E)-fl-farnesene,nerolidol, dehydration. INTRODUCTION (E)-fl-Farnesene (Figure l) is the main component of the alarm pheromone of many aphids (Bowers et aL, 1972; Edwards et al., 1973; Wientjens et al., 1973; Pickett and Griffiths, 1980). Crude (E)-~-farnesene [16o7o active ingredient (a.i.)] obtained from commercial nerolidol (Figure 1) by treatment with POCL#pyridine is as active on Myzus persicae as natural pheromone (Pickett and Griffiths, 1980) and in the laboratory increases effectiveness of the contact insecticide permethrin, presumably by stimulating aphid mobili- ty (Griffiths and Pickett, 1980). The objective of this study was to develop a convenient route to (E)-/~-farnesene on a large scale from easily obtained materials and to establish activity of this product with several species of economically important aphids. This would facilitate field investigation of the use of synthetic pheromone in conjunction with contact pesticides and the preparation of derivatives that might prevent settling and virus transmis- sion of aphids (Dawson et al., 1982). 11tl 0098-0331 / 82/0800-1111 $03.00/0 9 1982 Plenum Publishing Corporation