Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/14/2002
Publication Date: 4/15/2003
Citation: HOWARD,R.W., JACKSON,L.L., BANSE,H., BLOWS,M.W., CUTICULAR HYDROCARBONS OF DROSOPHILA BIRCHII AND D. SERRATA: IDENTIFICATION AND ROLE IN MATE CHOICE IN D. SERRATA, JOURNAL OF CHEMICAL ECOLOGY 29(4): 961-976. 2003. Interpretive Summary: Waxy lipids known as cuticular hydrocarbons are used by many insects to provide species-recognition cues and in many instances gender recognition and mating stimulant cues also. Little is known, however, about how these cues are selected for in natural populations. This study identified 47 hydrocarbons from two species of flies that live together and cross breed at low but persistent levels. It was shown for the first time using sophisticated statistical methods that it was the minor component hydrocarbons that were the cues that were used by the insects to control mate selection and not the major hydrocarbons. These findings suggest that other important insect communications systems might also depend on minor components that would not be detected except by using these statistical methods.
Technical Abstract: The cuticular hydrocarbon compositions of two sympatric species of Australian Drosophila in the montium subgroup of the melanogaster group, that use cuticular hydrocarbons in mate recognition, have been characterized. Drosophila birchii has 34 components in greater than trace amounts, with a carbon number range of C20 to C33. Drosophila serrata has 21 components above trace level and a carbon number range of C24 to C31. These two species share eight hydrocarbon components, with all but two of them being monoenes. For both species, the (Z)-9-monoenes are the predominant positional isomer. The hydrocarbons of D. birchii are n-alkanes, n-alkenes ((Z)-5-, (Z)-7-, (Z)-9-, and (Z)-11-), low to trace levels of homologous (Z,Z)-7,11- and (Z,Z)-9,13-dienes and trace amounts of (Z,Z)-5,9-C25:2, a major component of D. serrata. Only one methyl branched hydrocarbon was detected (2-methyl C28) and it occurred at very low levels. The hydrocarbons of D. serrata are dominated by a homologous series of (Z,Z)-5,9-dienes, and notably, are characterized by the apparent absence of n-alkanes. Homologous series of (Z)-5-, (Z)-7- and (Z)-9-alkenes are also present in D. serrata as well as low quantities of 2-methyl alkanes. Drosophila serrata females display strong directional mate choice based on male cuticular hydrocarbons, and prefer D. serrata males with higher relative abundances of the 2-methyl alkanes, but lower relative abundances of (Z,Z)-5,9-C24:2 and (Z)-9-C25:1.