K. Sawabe et A. Moribayashi, Lipid utilization for ovarian development in an autogenous mosquito, Culexpipiens molestus (Diptera : Culicidae), J MED ENT, 37(5), 2000, pp. 726-731
During the first ovarian cycle, autogenous female mosquitoes develop their
ovaries in the absence of blood feeding. In autogenous Culex pipiens molest
us (Forskal), complete yolk deposition was observed 2 d after emergence, ev
en when no feeding was allowed (starved). Neutral lipids in Cx. p. molestus
increased during the pupal stage, abruptly declined after emergence, and a
gain increased on day 3. In contrast, neutral lipids decreased in anautogen
ous Anopheles stephensi (Liston) and Cx. p. pallens (Coquillett) and starve
d females died within 2-3 d after emergence, nigh ratios of two major neutr
al lipids, free fatty acid and triglyceride, were isolated by thin-la)er ch
romatography (TLC) from the lipid contents of both Cx. p. molestus and An.
stephensi fourth-instars and newly emerged females. Fatty acid analyses usi
ng gas liquid chromatography (GLC) and GLC-mass spectrometry (GLC-MS) showe
d higher proportions of unsaturated than saturated fatty acids in Cx;. p, m
olestus at both stages and two major neutral lipids: free fatty acids and t
riglycerides. The percentage composition of linoleic acid (C18:2), which is
a precursor of arachidonic acid, was higher in Cx, p. molestus than in An.
stephensi. Our results indicated that elevated lipid content before emerge
nce may play a role of inducing ovarian development in autogenous mosquitoe
s.