Variation in rates of nitrogen fixation in termites: response to dietary nitrogen in the field and laboratory

Abstract

Abstract. Termites contribute nitrogen to their habitat through the nitrogenase activity of their bacterial symbionts. Previous studies indicate that high levels of dietary nitrogen suppress nitrogen fixation in termites. We examined the effects of dietary nitrogen on fixation rates in termites in both field and laboratory experiments. Ten field cplonies of Reticulitermes were collected and assayed for nitrogenase activity in July 1993, October 1993, January 1994, and April 1994. The nitrogen content of the wood collected with each colony was determined. There was no correlation between termite nitrogen fixation rates and the amount of nitrogen in their food for any of the four collection periods. In laboratory experiments, nitrogen fixation rates decreased when termites were fed filter paper treated with 2% and 5% ammonium nitrate or a 5% mixture of the amino acids proline, tryptophan and leucine, compared to water‐treated controls. By contrast, the nitrogenase activity of termites fed filter paper treated with 2% and 5% ammonium phosphate, a mixture of the amino acids histidine, serine and aspartic acid, or 2% and 5% urea did not differ from the controls. However, nitrogenase activity increased when termites were fed with 2% uric acid. No clear association exists between termite nitrogen fixation and the nitrogen content of their food.

Effect of Enhanced Dietary Nitrogen on Reproductive Maturation of the TermiteZootermopsis angusticollis(Isoptera: Termopsidae)

“…Storing less uric acid in the fat body may result in substantial weight reduction. A mechanism that regulates uric acid storage would be beneÞcial if there were a metabolic cost associated with uric acid retention; however, changes in dietary nitrogen have not been conclusively shown to inßu-ence the rate of nitrogen Þxation (Curtis and Waller 1997). Z. angusticollis primaries nesting with larvae show a similar decline in the rate of mass gain (Brent and Traniello 2001).…”

Parental Nitrogen Transfer and Apparent Absence of N2 Fixation during Colony Foundation in Coptotermes formosanus Shiraki

“…It has been reported that supplementing the diet of certain termites can result in lower N 2 fixation rates [ 9 , 29 ]. However, other studies have found no such relationship [ 30 ]. In nature, termites are known to selectively feed on certain nitrogen-rich parts of available food in their environment [ 6 , 26 , 27 ].…”

Trophic controls delaying foraging by termites: reasons for the ground being brown?

“…Variation in resource quality was simulated by adding nitrogen to the baits, which was based on the fact that termites are known to seek nitrogen-rich resources in the field (Shellman-Reeve, 1994). This was achieved by 'enriching' baits with 100 ml of a 3% w/v water solution of NH 4 NO 3 , as used by Curtis & Waller (1997) as the nitrogen source for termites in artificial diets. Baits, which were not nitrogen-enriched, received 100 ml of water.…”