Acetate esters of saturated and unsaturated alcohols (C12-C20) are major components in Dufour glands of Bracon cephi and Bracon lissogaster (Hymenoptera: Braconidae), parasitoids of the wheat stem sawfly, Cephus cinctus (Hymenoptera: Cephidae)

Chemistry of Dufour glands associated with the venom complex in Bracon cephi (Gahan) and Bracon lissogaster Muesebeck (Hymenoptera; Braconidae), two parasitoids of the wheat stem sawfly, Cephus cinctus Norton (Hymenoptera: Cephidae), was examined by solid phase micro-extraction (SPME) and gas chromatography/mass spectrometry. Homologous series of five chemical classes were detected in individual glands from each species. Major classes included: (1) acetate esters of saturated and unsaturated primary alcohols with parent chain lengths from C12 to C20. Hexadecanyl acetate, octadecanyl acetate, and octadecenyl acetate were major components in B. cephi. The composition of the acetate series in B. lissogaster was similar except that the octadecanyl acetate was only a minor component. (2) A homologous series of monoenes from C23:1 to C35:1 were detected in both species, with C29:1, C31:1 and C33:1 being the major components. Dienes from C31:2 to C35:2 and trienes (C33:3-C35:3) were also detected in both species. (3) A homologous series of n-alkanes from C19 to C31 was detected in both species. n-Tricosane was the major component. Minor components in both species included homologous series of both mono- and dimethyl branched alkanes. The Dufour gland hydrocarbon components in both B. cephi and B. lissogaster have some similarities to the composition of cuticular hydrocarbons of their host C. cinctus, a species with a complex pheromonal signaling system.