Colony structure and caste distribution in living trees of the Ryukyu drywood termite, Neotermes sugioi (Blattodea: Kalotermitidae) in Okinawa Island

Abstract

• Neotermes sugioi that attack living trees is a new species found from East Asia. • Broken of living tree trunks were may be caused by N. sugioi infestation. • Populations of 1,000–4,000 individuals were common in Neotermes sugioi colonies. • Reproductives were in the central or root side of the nest branches. • Regular pruning of dead branches of trees might help to remove small nests. Termites are major pests of houses and buildings, and also living plants such as agricultural crops, trees in forests, urban areas and gardens. However, in Japan, the basic ecology of termites nesting in living trees is not fully understood. In this study, we observed 255 colonies (nests) of the drywood termite Neotermes sugioi , collected in the field on Okinawa Island, and reported the frequency composition of the reproductive castes, the size of wood with termite gallery, the population size of colonies, and the relative position of the reproductive and non-reproductive castes within nests. Most colonies were headed by a primary queen and a primary king. However, colonies headed only by primary queens, primary kings, or neotenic kings, each accounted for approximately 5% of the colonies. A colony size of 1,000– 4,000 individuals (2058.2 ± 1695.0 [mean ± SD]) was common and the average length of colony branches was less than 100 cm. Queens and kings were found in the same or nearby nest areas, and more predominantly in the central or root side of nest wood areas. The termites may experience colony fragmentation and reproductive loss as a consequence of typhoons. Incipient colonies (i.e., colonies at an early stage of development) were found on 11.3% of branches of Leucaena leucocephala that did not show any obvious signs of infestation. In future research, it will be necessary to update the list of trees damaged by this termite species, compare the damage by tree species, and evaluate the economic impact.