Fatty acid composition of aquatic insect larvae Stictochironomus pictulus (Diptera: Chironomidae): evidence of feeding upon methanotrophic bacteria.
Larvae of the chironomid Stictochironomus pictulus were collected from Lake Biwa, central Japan. Both the fatty acid composition of the total lipid fraction and the carbon stable isotope ratios of whole larvae were determined. Larvae showed delta(13)C values of -57.4 per thousand to -62.4 per thousand, similar to the values of methane recorded from the lake sediments. A high level of monounsaturated fatty acids (MUFAs; approximately 50% of total fatty acids) and an extremely low level of n-3 series polyunsaturated fatty acids (PUFAs) in the total lipids of S. pictulus indicated a predominantly bacterial nutrition for this species. Moreover, chironomid tissues contained large amounts of the Type I methanotroph group-specific fatty acid, 16:1(n-8) (approximately 8% of total fatty acids). This is the first time such a fatty acid biomarker has been described from freshwater invertebrates. The data suggest that S. pictulus larvae directly feed upon methanotrophic bacteria.
Kiyashko
Serguei I
SI
Institute of Marine Biology, Far East Branch of Russian Academy of Sciences, Vladivostok 690041, Russia. sekiyash@hotmail.com
Imbs
Andrey B
AB
Narita
Tetsuya
T
Svetashev
Vassilii I
VI
Wada
Eitaro
E
D000818:Animals; D001419:Bacteria / Q000737:chemistry; D002247:Carbon Isotopes / Q000737:chemistry; D002683:Chironomidae / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism*; D005229:Fatty Acids, Monounsaturated / Q000378:metabolism*; D007814:Larva / Q000378:metabolism; D008697:Methane / Q000378:metabolism*; D014871:Water Microbiology
D002247:Carbon Isotopes; D005227:Fatty Acids; D005229:Fatty Acids, Monounsaturated; D008697:Methane