Identification of (Z)-4-tridecene from defensive secretion of green lacewing, Chrysoperla carnea

We report the identification of a defensive secretion from the green lacewi ng, Chrysoperla carnea. By using combined gas chromatography-electroantenno graphic detection (GC-EAD), we found one major compound in the solvent extr act of this secretion that elicited a significant EAD response from the ant enna. Based upon its characteristic fragments from gas chromatography-mass spectrometry (GC-MS) analysis, the compound was identified as a tridecene. Dimethyldisulfide derivatization suggested that a double bond was located b etween positions 4 and 5 in the carbon chain. Thus, the compound was tentat ively identified as a 4-tridecene. Coinjection of the extract with a mixtur e of the Z or E form of the synthetic 4-tridecene revealed that the unknown was (Z)-4-tridecene. EAG dose-responses showed a direct correlation to dos e. Single sensillum recordings from sensilla trichodea situated on the ante nnae suggested the presence of receptor neurons specifically responding to this compound. An arrestment behavior was observed when tested in the Y-tub e olfactometer. Preliminary field trapping results indicate that the compou nd is an antagonist to attraction. The avoidance behavior of predatory ants , observed when tested with the synthetic compound of this secretion furthe r suggested a defensive function.