FUNGAL ODOR DISCRIMINATION IN 2 SYMPATRIC SPECIES OF FUNGIVOROUS COLLEMBOLANS

1. Resource partitioning of two sympatric species of collembolans, Orc hesella cincta and Tomocerus flavescens, was explored from differences in their food odour perception. 2. Preferences of the collembolans of odours from four fungal species and a green alga were tested in a Y-t ube olfactometer. The collembolans were separated by only one differen ce in odour preference; Cladosporium herbarum was significantly more a ttractive to O. cincta than the other food sources, whereas T. flavesc ens was most attracted to Mortierella isabellina. 3. Fungal odours wer e trapped in an activated carbon filter, extracted with diethylether a nd subjected to GC-MS analysis. The analysis revealed a number of diff erences in the odour composition of the two fungal species but the odo ur of C. herbarum could not be distinguished from that of C. cladospor ioides, which was lower ranked by O. cincta. 4. Nine fungal odour comp ounds were used in an electroantennogram (EAG) assay. There were diffe rences in antennal responses between the collembolan species to 2-meth yl-1-propanol, dipentene, 1-octanol and camphor. The identity of the c ompounds responsible for attracting O. cincta to C. herbarum and T. fl avescens to M. isabellina could not be resolved. A cluster analysis of the EAG responses emphasized the physiological origin of the differen ces in food preferences between the two collembolan species and sugges ted that P. cincta was more variable in its odour perception than T. f lavescens.