Fatty acid composition of aquatic insect larvae Stictochironomus pictulus (Diptera: Chironomidae): evidence of feeding upon methanotrophic bacteria

• Published in: Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology Vol. 139; no. 4; pp. 705 - 711
• Main Authors: Kiyashko, Serguei I., Imbs, Andrey B., Narita, Tetsuya, Svetashev, Vassilii I., Wada, Eitaro
• Format: Journal Article
• Language: English
• Published: England Elsevier Inc 01-12-2004
• Subjects: Animals; aquatic insects; Bacteria - chemistry; Carbon Isotopes - chemistry; Chironomidae; Chironomidae - metabolism; Fatty acids; Fatty Acids - metabolism; Fatty Acids, Monounsaturated - metabolism; Feeding; feeding behavior; Food webs; Lake Biwa; Larva - metabolism; Lipid biomarkers; Methane - metabolism; methanogens; Methanotrophic bacteria; monounsaturated fatty acids; omega-3 fatty acids; Sediment phospholipids; Stable isotopes; Stictochironomus pictulus; Water Microbiology; Japan, Honshu, Shiga Prefect., Biwa L; Chironomidae; Methanotrophic bacteria; Stable isotopes; Lipid biomarkers; Food webs; Lake Biwa; Sediment phospholipids; Fatty acids; Feeding
• ISSN: 1096-4959; 1879-1107
• DOI: 10.1016/j.cbpc.2004.08.013

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
δ
13C values of −57.4‰ to −62.4‰, 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.