THE ROLE OF GLYCOGEN DURING THE ONTOGENY OF CHIRONOMUS-ANTHRACINUS (CHIRONOMIDAE, DIPTERA)

Large fluctuations in glycogen content were found in larvae, pupae and adults of Chironomus anthracinus (Zetterstedt) from the profundal zon e of Lake Esrom, Denmark. In 2nd, 3rd and 4th instar larvae the glycog en concentration (expressed as percentage of dry weight) increased dur ing periods of aerobic conditions to a maximum of 25%, but decreased i n periods of hypoxia longer than two months to 10-12% in young larvae. A further decrease to about 5% took place, when moulting from 2nd to 3rd or from 3rd to 4th instar occurred after overturn. Prior to pupati on the glycogen concentration was restored to 26-28%. The glycogen con centration approximated 22% in young pupae, but decreased during the p upal stage and newly hatched adults contained 12-15%. Finally, the gly cogen store of both males and females was further reduced during the s warming period. Thus, glycogen seems to be an important energy source (1) during periods with hypoxic conditions, (2) during periods with hi gh internal energy requirement such as ecdyses and metamorphosis, and (3) during the non-feeding adult life stage.