Comparison of gut contents and assimilation efficiency of fourth instar larvae of two coexisting chironomids, Chironomus riparius Meigen and Glyptotendipes paripes (Edwards)

Publisher Website
Google Scholar
Abstract
Responses to experimental manipulation, behavioral observations, and tube morphology all suggested that Glyptotendipes paripes and Chironomus riparius from Stephenson Pond (near Calgary) have different feeding mechanisms, and that G. paripes was a filter feeder and C. riparius, a deposit feeder. This hypothesis was supported by microscopical analysis of gut contents of fourth instar larvae of the two species. Chironomus riparius guts contained mainly silt particles and microdetritus fragments, whereas G. paripes guts contained mainly planktonic diatoms and microdetritus, with very little silt present. The anterior midgut contents of G. paripes exhibited significantly greater loss on ignition than the anterior midgut contents of C. riparius; however, ignition loss from the posterior midgut was not significantly different between the two species. These results are consistent with the differences found by microscopical analysis and show that (i) the material ingested by G. paripes was of higher organic content (37.6%) than that ingested by C. riparius (30.2%), and (ii) G. paripes assimilated a higher portion (11.9%) of what it ingested than did C. riparius (5.9%). The differences in feeding mechanisms are probably of considerable significance in permitting these two species to coexist at the high larval densities sometimes present in small ponds.