Submitted to: International Biodeterioration and Biodegradation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/6/2006
Publication Date: 8/24/2006
Citation: Doolittle, M., Raina, A.K., Lax, A.R., Boopathy, R. 2006. Effect of natural products on gut endosymbiotic microbes in formosan subterranean termites. International Biodeterioration and Biodegradation. 59:69-71.
Interpretive Summary: The Formosan subterranean termite is a major urban pest in the southern states and Hawaii, destroying wooden structures and live trees. Most of the digestion of cellulose from wood is accomplished by symbiotic microbes in the hind gut of the termite. Without these microbes, the termites would be unable to survive. Three natural products originating from neem, chili peppers and honey locust were tested to determine their effect on reducing or eliminating the gut microbes. Only the neem extract significantly reduced the population of two of the four gut microbes. Having established the protocol for determining the effect of natural products on gut microbes, it will be easier to evaluate other natural products.
Technical Abstract: The Formosan subterranean termite (FST) was first detected in Houston, Texas, in 1965 and since then it has caused billions of dollars worth of economic damage. Lower termites such as the Formosan termite contain endogenous cellulases that are capable of breaking down only a small fraction of the cellulose needed to sustain the termite. Without the aid of endosymbiotic hindgut microbes to further breakdown the remaining cellulose, the FST would be unable to survive. Therefore, the objective of this study was to test the ability of three natural products (azadirchtin, capsaicin, and gleditschia) to reduce the number of termite hindgut microbes, thereby lowering the survival of the termite. Termites were placed in Petri dishes containing a food source soaked in one of these compounds. The number of gut microbes was counted over a defined time period and then the microbial populations were analyzed for a significant change in abundance. The three flagellated protozoan species that inhabit the Formosan termite’s hindgut (Pseudotrichonympha grassii, Spirotrichonympha leidy, and Holomastigotoides hartomanni) were counted along with spirochetes. The results indicated that the azadirachtin (Neem extract) was capable of reducing the population of P. grassii and spirochetes. Neem extract also showed significant termite mortality. However, Gleditschia and capsaicin did not reduce the termite gut microbial population at the concentrations used in this study.