Abstract: 【Aim】 This study aims to find the time of establishment and maintenance of dominant reproductive status and the variations of relevant cuticular long-chained hydrocarbons (CHCs) in neotenic reproductives of Reticulitermes labralis. 【Methods】 Orphaned colonies of R. labralis were established in the laboratory. The time of establishment and maintenance of stable reproductive status for neotenic reproductives was determined via the differentiation observation. The variations of relevant CHCs in different developmental stages of neotenic reproductives were analyzed with gas chromatography-mass spectrometer (GC-MS). 【Results】 With the appearance of neotenic reproductives of R. labralis, each colony gradually had its dominant reproductives (stable reproductives). Colonies with stable reproductives accounted for 43.3%, 83.3%, 93.3% and 100% of the orphaned groups on the 8th, 16th, 25th and 36th day, respectively. By analyzing the peak area ratios (the peak area at each stage divided by the area of the corresponding peak at the nymphal stage) in different stages of neotenic reproductives, we found that the peak area ratio of the compound with the retention time of 38.52 min, which was not detected in eggs, was 14.14 times in reproductives laying 7-8 eggs as high as that in the nymphal stage, while the compounds with the retention time of 35.50 and 39.21 min, which were detected in eggs, had significantly increased peak area ratios after the reproductives began to lay eggs. 【Conclusion】 CHCs can not be used to discriminate fertile neotenics (neotenic reproductives that establish and maintain dominant reproductive status) from infertile neotenic reproductives (individuals with morph of neotenics, but unable to lay eggs in the colony) of R. labralis, although they can be used to discriminate neotenic reproductives from nymphs easily. The compound with the retention time of 38.52 min is a characteristic substance of reproductives. The compounds with the retention time of 35.50 and 39.21 min are characteristic substances of neotenic reproductives that have laid eggs.

Key words: Reticulitermes labralis , cuticular long-chained hydrocarbons, neotenic reproductives, nymph, caste differentiation, pheromone