Nitrogen-sparged media extends life span of symbiotic protists found in subterranean termites (Isoptera: Rhinotermitidae), providing more time for microscopic examination

Abstract

Protist communities found in the hindgut of subterranean termites (Rhinotermitidae) historically have been quantified and identified using a variety of methods, thus making comparisons between studies difficult. We examined four saline solutions and compared protist estimates by using two different cell-counting platforms. Estimates of protist populations were greater using a hemocytometer counting chamber than sealed coverslip mounts. Estimates of the protist population per Reticulitermes flavipes (Kollar) worker averaged 90,000 in Trager U, 79,000 in Ritter, 68,000 in Mannesmann, and 50,000 in 0.6% NaCl saline solutions. The percentage of protist survivorship significantly decreased after 5 min under microscopic examination in untreated media. Sparging one of the saline solutions (Trager U) with nitrogen gas provided a solution where protist populations averaged 91,000 and percentage of protist survivorship did not significantly decrease for 15 min. Identification and quantification of protists require time, and extending cell life provides more time to make accurate counts. We therefore propose the technique described in this study be adopted for its ease of use and improved accuracy.