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Parental Nitrogen Transfer and Apparent Absence of N<sub>2</sub> Fixation during Colony Foundation in <em>Coptotermes formosanus</em> Shiraki

Mullins, Aaron, Su, Nan-Yao
Insects 2018 v.9 no.2
Coptotermes formosanus, biomass, dietary nutrient sources, inventories, nitrogen, nitrogen-fixing bacteria, rearing, total nitrogen
Colony foundation and early growth is a critical period in the life-cycle of a termite colony, as the initial family unit is resource limited. One such resource is nitrogen, which is essential for initial colony growth. This study examined the whole-colony nitrogen inventory during foundation and early growth of Coptotermes formosanus Shiraki colonies. It was hypothesized that termite colonies would go through an initial period of parental investment, representing a transfer of nitrogen to the first brood, and that once a functional worker caste was present, further provisioning in the form of intrinsic N<inf>2</inf> fixation would occur. Our results showed that, when in nitrogen-poor rearing conditions, the king and queen initially transferred half of their nitrogen reserves to their first brood. However, the total nitrogen content in colonies did not increase over a 12 month period, despite the presence of functional workers. Furthermore, colonies did not increase their biomass beyond the initial parental investment. Together, these results imply that nitrogen acquisition in incipient C. formosanus colonies relies on environmental or dietary sources, rather than the putative fixation through symbiotic diazotrophs.