Sex pheromone of the tsetse species, Glossina austeni: isolation and identification of natural hydrocarbons, and bioassay of synthesized compounds

Abstract

Copulatory responses of male Glossina austeni (Newstead) (Diptera: Glossinidae), that were elicited after contact with frozen female tsetse, were not observed after solvent washing of cuticular lipids. Chromatographic analysis of extracts from laboratory-reared and field-collected G. austeni females yielded natural hydrocarbons that were highly stimulatory to males. Most of this activity was produced by compounds in the alkene fraction. Gas chromatograms (GC) contained five natural alkenes; these were separated by preparative GC for bioassays conducted in Tanzania. The two major alkenes were identified using gas chromatography-mass spectrometry (GC-MS) to be 13,17-dimethyltritriacont-1-ene and 13,17-dimethylpentatriacont-1-ene, after the samples had undergone derivatization using dimethyl disulphide and saturation with deuterium. These alkenes and natural alkanes were quantified from G. austeni of both sexes from laboratory and field samples to confirm that their presence was consistent in this species. Trials of synthetic samples resulted in the order of biological activity for the stereoisomers of 13,17-dimethyltritriacont-1-ene as follows: S,R-33:1 > R,S- 33:1 > S,S-33:1 > R,R-33:1. Dose-response data showed an ED(50) at 5 microg per treated, solvent-washed male decoy. Of the four stereoisomers of 13,17-dimethylpentatriacont-1-ene, R,R-35:1 showed the most activity. This is the first report of alkene-induced sexual activity in males of the genus Glossina.

Cuticular hydrocarbons as contact sex pheromone in the parasitoid Dibrachys cavus

“…Although an important function of methylalkanes as contact sex pheromones in insects has been established in a number of species, almost nothing is known about the absolute configuration of the natural products and the possible enantioselectivity of the responders (but see, e.g., Carlson et al, 2005). The reason for this is probably the lack of analytical tools to separate the enantiomers of longchain chiral methylalkanes and enantiomerically pure reference chemicals that are more elaborate to synthesize (Millar, 2010).…”

Tolerance Requires the Right Smell: First Evidence for Interspecific Selection on Chemical Recognition Cues

“…Methylbranched alkenes are extremely rare among insects in general and have been found in merely three ant genera up to now (Francke et al 2000; Etges and Jackson 2001; Carlson et al 2005; Martin and Drijfhout 2009). However, we detected them in 16 nontolerated and tolerated Camponotus species from seven subgenera.…”

Sexual dimorphism in cuticular hydrocarbons of the Australian field cricket Teleogryllus oceanicus (Orthoptera: Gryllidae)

“…Appendix. Insect species in which sexual dimorphism of cuticular hydrocarbons has been investigated Carlson et al (2005), Nelson and Carlson (1986)…”