Unusual polymethyl alkenes in tsetse flies acting as abstinon inGlossina morsitans

The major alkene of the male tsetse fly,Glossina morsitans morsitans, was isolated for characterization by thin-layer and gas chromatography (GC). The mass spectra of the alkene and the alkene DMDS derivative indicated one isomer, 19,23-dimethyltritriacont-1-ene. The material is present at 1-2μg/male fly and is partially transferred to the female preparatory to or during mating. A dose-dependent antiaphrodisiac effect was seen with exposed male flies using the isolated natural product, with 2 and 4μg causing 80% loss of copulatory attempts, and 10μg extinguishing the attempts. This effect was increased by addition of male-produced alkane. This compound and a 31-carbon homolog also appear inG. m. submorsitans. Similar quantities of alkenes that are species-specific appear in all tsetse males. Structures of male-produced trimethylalkenes that appear in two other species,G. palpalis palpalis andG. fuscipes fuscipes, were investigated.