Female-released sex pheromones mediating courtship behavior in Lysiphlebus testaceipes males.

Ethological aspects and chemical communication at close-range between the sexes of Lysiphlebustestaceipes Cresson (Hymenoptera: Braconidae) have been investigated throughbehavioral bioassays and chemical analysis. The attractiveness toward males of whole-bodyextracts of females and males in hexane and acetone was evaluated, adopting male fanningbehavior as a key behavioral component. Also, the activity of polar and nonpolar fraction offemale-body extract in hexane obtained using solid-phase extraction technique was investigated.In order to identify cuticular compounds, male and female whole-body extracts withhexane and acetone were analyzed by gas chromatography-mass spectrometry. The resultsshowed that males exhibit a behavior including 4 phases when exposed to virgin females: premount,mount, copulation, and post-copulation. A preliminary courtship of the male includedwing fanning, an extension and vibration of the wings for 1 to 2 seconds. Also, some originalaspects not described for other species were carried out. The average duration of the entire sequenceof events was 138.80 ± 19.51 sec. Also, males displayed significantly more wingfanning behavior in response to female whole-body hexane extracts (70.83%) than femalewhole-body acetone extracts (33.3%). Furthermore, males did not respond to male-body extractsor to the control (pure hexane and acetone), suggesting that the sex pheromone iscomposed of cuticular hydrocarbons that are also involved in the male courtship behavior.When hexane extracts of whole females were fractionated on silica gel and exposed to males,more activity was recorded for the nonpolar fraction (50.0%) than the polar fraction (27.7%),but no significant statistical difference was found. Significant differences were detected comparingthe control (not fractionated extract) with the polar fraction, but not with the nonpolarfraction. A homologous series of n-alkanes with chain lengths from C19 to C30 carbon atomswas identified and quantified in the solvent extracts of wasp males and females. Between maleand female extracts, there was a statistically significant difference in the average quantity ofsome of these hydrocarbons, such as C27, C28, and C29.