THE INFLUENCE OF BLOOD MEALS ON ACCUMULATION OF ARACHIDONIC-ACID BY ADULT STABLE FLIES

We investigated the influence of blood meals on accumulation of the po lyunsaturated fatty acid (PUFA), 20:4n-6, by adult stable flies, Stomo xys calcitrans (L.). The fatty acid compositions of phospholipids (PLs ) and triacylglycerols (TGs) prepared from adult male and female stabl e flies that had been maintained either with or without blood meals we re determined, and incorporation of exogenous radioactive fatty acids into tissue lipids of adults was monitored. The major PL components we re 16:0, 16:1, 18:1 and 18:2n-6. Two C-20 PUFAs, 20:4n-6 and 20:5n-3 w ere associated with PLs in the 1-5% range. The major TG components wer e 14:0 and 16:1. Although absence of the normal adult blood meals infl uenced the overall fatty acid profiles of male and female stable flies , proportions of C-20 PUFAs in PLs of blood-fed flies were not substan tially higher than proportions of C-20 PUFAs in their sucrose-fed coun terparts. The fatty acid incorporation studies indicate that the abili ty to incorporate exogenous fatty acids is decreased in older adult st able flies. We conclude that the larval stages of stable flies are mor e important for accumulation of C-20 PUFAs than the adult stages.