The trophic ecology of five shredder taxa found in Mink Creek, Idaho w
as determined in laboratory food quality experiments to assess the obl
igate or facultative nature of resource utilization among lotic taxa c
ommonly referred to as detritivores. The experiments tested resource a
ssimilation for each taxon among three major resources available to pr
imary consumers in streams; periphyton, fine particulate detrital mate
rial (FPM) and coarse particulate detrital material (CPM). Growth of e
ach taxon was determined on each resource in laboratory experiments co
nducted at 10 degrees C. Growth results indicate that only one of the
five taxa (middle-late instar Dicosmoecus atripes) was an obligate CPM
detritivore. The remaining four taxa (Amphinemura banksi, Lepidostoma
sp., Podmosta delicatula, and Zapada cinctipes) were generalists capa
ble of growth on at least two of the three resource types. Ail four ge
neralists exhibited growth on periphyton and CPM resources suggesting
that these taxa can utilize both autochthonous and allochthonous resou
rces. Our results do not support the idea that taxa with similar mouth
part morphology, specifically shredders, exhibit similar trophic relat
ionships.