Unusual polymethyl alkenes in tsetse flies acting as abstinon in Glossina 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 1-2 μg/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 4 μg causing 80% loss of copulatory attempts, and 10 μg extinguishing the attempts. This effect was increased by addition of male-produced alkane. This compound and a 31-carbon homolog also appear in G. 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 and G. fuscipes fuscipes, were investigated.