Nitrous Oxide (N2O) Emissions by Termites: Does the Feeding Guild Matter?

Area of Science:

• Ecology
• Environmental Science
• Soil Biology

Background:

• Termites are key decomposers in tropical ecosystems, influencing nutrient cycling and greenhouse gas production.
• Nitrous oxide (N2O) is a potent greenhouse gas with significant contributions from soil microbial processes.
• Termite N-metabolism and N2O production are influenced by their diverse feeding habits (feeding guilds).

Purpose of the Study:

• To investigate how termite feeding guilds affect N2O emission levels.
• To test the hypothesis that termites consuming nitrogen-rich diets produce more N2O.
• To quantify N2O production across various termite species and biomes.

Main Methods:

• An in-vitro incubation approach was employed to measure N2O production.
• Fourteen termite species from different feeding guilds were collected across diverse biomes.
• Termite guts were analyzed for ammonia-oxidizing and denitrifying gene markers (amoA-AOB, amoA-AOA, nirK, nirS, nosZ).

Main Results:

• Soil-feeding and fungus-growing termites were N2O producers, while wood-feeding termites were N2O consumers.
• N2O production varied significantly: 13.14–117.62 ng N2O-N d⁻¹ (g dry wt.)⁻¹ for soil-feeders and 39.61–65.61 ng N2O-N d⁻¹ (g dry wt.)⁻¹ for fungus-growers.
• Incubating termites with their mounds amplified N2O production by 6–34 fold, particularly in soil-feeding and fungus-growing species.
• No correlation was found between the abundance of specific microbial genes and N2O production levels.

Conclusions:

• Termite feeding guild is a significant determinant of N2O emission rates.
• Termites feeding on nitrogen-rich substrates (soil, fungi) exhibit higher N2O production compared to those on nitrogen-poor wood.
• The study supports the hypothesis linking higher nitrogen content in diet to increased N2O production in termites.