Composition of triglycerides from aphids of six different families and from different seasonal forms of Aphis evonymi

The triglyceride compositions of extracts and cornicle secretions of specimens from a range of aphid families were examined by mass spectrometry and found to support earlier evidence that there is little correlation between taxonomic position and chemical constitution. Parasites developing within Myzus persicae preferentially consumed the typical aphid triglycerides which contain hexanoic (C 6), sorbic (C 6:2), myristic (C 14), and palmitic (C 16) acid moieties, so that when parasitism was advanced, only triglycerides with three long-chain fatty acids per molecule remained. The adult parasites themselves contained very little triglyceride. Triglycerides of Aphis evonymi and Aphis fabae were similar and varied in composition regularly throughout the year. In the apterous and alate (summer) viviparae, there were equal amounts of myristoyl (C 14) and palmitoyl (C 16) triglycerides, while in fundatrices and fundatrigeniae (spring forms) myristoyl was predominant. Males collected in autumn resembled the spring forms. However, oviparae and eggs of these and other species differed considerably from the other seasonal forms, in having more hexenoic (C 6:1), sorbic (C 6:2), and myristoleic (C 14:1) acid moieties.