C-4-4

THE ROLE OF BREVICORYNE BRASSICAE SEX PHEROMONES AND PLANT ODOURS IN ATTRACTING APHID PARASITOIDS IN THE FIELD

Beata Gabrys¹, Henryk Gadomski¹, Zdzislaw Klukowski¹, John A. Pickett², Grazyna Sobota¹, Lester J. Wadhams² and Christine M. Woodcock^2
1Dept. of Agricultural Entomology, Agricultural University, Cybulskiego 32, 50-205 Wroclaw, Poland.
²IACR-Rothamsted, Harpenden, Herts., AL5 2JQ, UK

(4aS, 7S, 7aR)-nepetalactone was identified as a sex pheromone of Brevicoryne brassicae (Homoptera: Aphididae) by GC and GC-MS analysis, and by electrophysiological recordings from olfactory cells associated with the secondary rhinaria of the male antennae. The compound proved to be attractive in a laboratory bioassay using a simple choice chamber. The release of the pheromone from glass vials placed above water traps in oilseed rape crop in spring and autumn increased the catch of B. brassicae males in autumn. The significantly larger numbers of Diaeretiella rapae (the specialist parasitoid of B. brassicae) were found in pheromone traps as compared to controls in spring and autumn. Praon volucre (the generalist parasitoid) occurred in larger numbers in pheromone traps only in autumn. The addition of 2-phenylethyl isothiocyanate (a compound giving odour to oilseed rape) did not increase the catch of D. rapae females in spring and autumn. The catches of P. volucre were larger in traps releasing plant odours and aphid sex pheromones as compared to pheromone traps in autumn.