Role of autochthonous and allochthonous basal resources on tire insect communities

In recent decades there has been an increased effort to examine the importance of organic matter (OM) resources on insect community structure. In particular, there has been a greater need to distinguish among OM resources which originate from outside the ecosystem (allochthonous) and those from within the system (autochthonous). Although, there has been much examination of the sources of OM resources that support food webs in a variety of lotic and lentic systems, there still remains a need for understanding their importance to aquatic insect communities in tire ecosystems. The aim of this study was to examine the role of basal resources on macroinvertebrate community structure in tires. Our study was conducted in summer 2012 and had seven treatments which included periphyton only (autochthonous), animal detritus only (allochthonous), leaf detritus only (allochthonous), or combination of two or three resource types. Additionally, insect community information (e.g. species richness and abundance), bacterial productivity, total and dissolved nutrients, leaf and animal detritus breakdown, and primary productivity was assessed every five weeks. Further, we assessed relative importance of OM sources and food web structure using C and N stable isotopes. Results from the early summer sampling period showed that insect communities in all treatment types were dominated by Dipteran species with Culicidae and Chironomidae most abundant. Further, tires with the leaf only treatment had significantly lower mosquito abundances than tires with periphyton and animal detritus; however, mosquito abundance was not significantly different among all other treatments. Further, we found there was not a significant difference in other taxa abundances or taxa richness among treatments. This study will help to further explore the relationships between resources and aquatic insect production in container systems.