Arachidonic and eicosapentaenoic acids in tissues of the firefly, Photinuspyralis (Insecta : Coleoptera)

We report on the presence of high proportions of arachidonic acid (20:4n-6) and eicosapentaenoic acid (20:5n-3) in the tissue lipids of adult fireflie s, Photinus pyralis. Arachidonic acid typically occurs in very small propor tions in phospholipids (PLs) of terrestrial insects, ranging from no more t han traces to less than 1% of PL fatty acids, while 20:5n-3 is often missin g entirely from insect Lipids. Contrarily, 20:4n-6 made up approximately 21 % of the PL fatty acids prepared from whole males and females, and from hea ds and thoraces prepared from males. Proportions of 20:4n-6 associated with PLs varied among tissues, including approximately 8% for male gut epitheli a, 13% for testes, and approximately 25% for light organs and body fat from males. Substantial proportions of 20:5n-3 were also associated with PLs pr epared from male firefly tissues, including 5% for body fat and 8% for ligh t organs. Because 20:4n-6 and 20:5n-3 are precursors for biosynthesis of pr ostaglandins and other eicosanoids, we considered the possibility that fire fly tissues might produce eicosanoids at exceptionally high rates. Prelimin ary experiments indicated otherwise. Hence, fireflies are peculiar among te rrestrial insects with respect to maintaining high proportions of PL 20:4n- 6 and 20:5n-3. (C) 2001 Elsevier Science Inc. All rights reserved.