Synchronization of alate emergence among colonies and dispersal strategy in the Ryukyu dry-wood termite Neotermes sugioi (Isoptera: Kalotermitidae)

The synchronized dispersal of colonies is an important strategy among social insects in terms of both successful mating and the avoidance of inbreeding. Although several studies have focused on these processes in the most common termite species characterized by pulsed dispersal, only a few studies have reported on termite species characterized by continuous dispersal. Here, we describe the phenology and biological characters of the dispersal flight of Neotermes sugioi, a dry-wood termite native to the Ryukyus Islands of Japan, using five colonies isolated under semi-field conditions over a period of 183 days. We obtained evidence for the synchronicity of alate emergence among colonies of N. sugioi based on observations of synchronous patterns on the major flight and non-flight days, which showed positive correlations in alate emergence between all colony pairs. However, due to the occurrence of months with small correlation coefficients, and inconsistent alate emergence peaks among colonies on a single day, N. sugioi showed less synchronization than subterranean termites characterized by pulsed dispersal flights. Environmental conditions of temperatures and humidities greater than 22 degrees C and 70% were found to be necessary for high flight activity during both high and low flight seasons. In all colonies, the sex ratio of emerging alates during the observation period was significantly biased toward males. Given that adjustment of synchronous and asynchronous alate release among neighboring colonies could reduce the risk of sibling pair mating and inbreeding, the characteristic alate emergence in N. sugioi may indirectly minimize the potential for inbreeding.