ARACHIDONIC AND EICOSAPENTAENOIC ACIDS IN TISSUE-LIPIDS OF 2 SPECIES OF PREDACIOUS INSECTS, CICINDELA-CIRCUMPICTA AND ASILIS SP

1. C20 polyunsaturated fatty acids usually occur only in trace quantities in the lipids of terrestrial insects and are frequently overlooked in studies of insect lipid biochemistry. 2. In two terrestrial predacious insects, the tiger beetle Cicindela circumpicta and a robber fly Asilis sp., arachidonic acid (20:4n-6) and eicosapentaenoic acid (20:5n-3) comprised about 5% and 12%, respectively, of phospholipid fatty acids. 3. These are unusually high values for terrestrial insects, indicating the potential for biosynthesis of 2- and 3-series prostaglandins, as well as other possible physiological roles beyond eicosanoid biosynthesis. 4. Both predators contained an extensive series of fatty acids that are rarely detailed in insect lipids, including odd-chain, methyl-branched, and multiple double-bond positional isomers.