Chemical Attraction of Conspecifics in Folsomia candida (Collembola)

Chemical substances excreted from individuals are regarded as chemo-sensory signals that induce aggregation in Collembola. However, chemical or physiological evidence is required to identify the chemical composition of signals responsible for aggregation behavior. Present study applied solvent extraction and gas chromatograph-mass spectrometer-computer technology to separate and identify the chemical compounds in cuticle extracts from the model Collembola species, Folsomia candida. The occurrence of aggregation behavior was confirmed by conspecific attractiveness using a trap bioassay. Eight chemical compounds were obtained from F. candida's cuticle solvent. The trap assay detected fatty acid combinations from the body extracts of F. candida that induced attractiveness behavior among conspecific individuals and small molecules with higher concentration induced repellent. However, single sensillum recordings of two thin-wall chemical receptors at the second segment of the distal position of the antenna did not receive any positive responses to fatty acids, either single or in combination. The way F. candida used fatty acid combinations as chemical signal for conspecific aggregating was discussed