Secretion of Thrips VIII : Secretions of the Two Ponticulothrips Species (Thysanoptera: Phlaeothripidae)

The yellow secretions of two phlaeothripine thrips, Ponticulothrips diospyrosi and a closely related, underscribed species, P. sp. (Thysanoptera : Phlaeothripidae) were analyzed by GLC, GC-MS and TLC. Six components were detected from both species, four of which were identified as plumbagin (2-methyljuglone), 7-methyljuglone, (Z)-5-tetradecenoic acid and tetradecadienoic acid. (Z)-5-Tetradecenoic acid was a main component (62.5%) in P. diospyrosi, while in P. sp., as yet unidentified component was dominant (42.4%) ; thus, the two species were easily distinguished by comparing the GLC profiles. Plumbagin showed repellency against ants at dosses of more than 1.0 μg in the laboratory assay while (Z)-5-tetradecenoic acid exhibited no significant activity at 1.0μg. Thus, plumbagin appeared to be an active principle of the secretions. The role of (Z)-5-tetradecenoic acid is discussed. This study represents the first time that these two naphthoquinones were isolated from an animal source.