The disruption of host-symbiont interactions through the use of antibiotics can help elucidate microbial functions that go beyond short-term nutritional value. Termite gut symbionts have been studied extensively, but little is known about their impact on the termite's reproductive output. Here we describe the effect that the antibiotic rifampin has not only on the gut microbial diversity but also on the longevity, fecundity, and weight of two termite species, Zootermopsis angusticollis and Reticulitermes flavipes. We report three key findings: (i) the antibiotic rifampin, when fed to primary reproductives during the incipient stages of colony foundation, causes a permanent reduction in the diversity of gut bacteria and a transitory effect on the density of the protozoan community; (ii) rifampin treatment reduces oviposition rates of queens, translating into delayed colony growth and ultimately reduced colony fitness; and (iii) the initial dosages of rifampin had severe long-term fitness effects on Z. angusticollis. Taken together, our findings demonstrate that the antibiotic-induced perturbation of the microbial community is associated with prolonged reductions in longevity and fecundity. A causal relationship between these changes in the gut microbial population structures and fitness is suggested by the acquisition of opportunistic pathogens and incompetence of the termites to restore a pretreatment, native microbiota. Our results indicate that antibiotic treatment significantly alters the termite's microbiota, reproduction, colony establishment, and ultimately colony growth and development. We discuss the implications for antimicrobials as a new application to the control of termite pest species.The long-standing associations between termites and prokaryotic and eukaryotic microorganisms have been crucial to the evolutionary and ecological success of this social insect group. The presence of cellulolytic microorganisms in the hindguts of termites is one of the key events that allowed termites to thrive on nitrogenously deficient food resources (49, 63). Fossil records (80) and the similarity in gut flora and other microbial endosymbionts with those of their roach relatives (59) support the hypothesis that these associations existed in the termite ancestor (3,50,59). Termite gut symbionts reside in the lumen or are attached to the wall of the hindgut region and can represent more than 40% of the termite's weight (6). They are horizontally transmitted through coprophagy, a common behavior in termites. Indeed, the need for transfaunation of hindgut symbionts has been proposed as one of the main factors favoring group living (44) and specifically favoring the evolution and maintenance of termite sociality (18). However, little is known about the impact that termite gut symbionts have beyond their role in cellulose degradation and host nutrition.Here we report on the impact that antibiotic treatment has on the reproductive survival and fecundity of the dampwood termite Zootermopsis angusticollis and the Eastern su...

Termites have had a long co-evolutionary history with prokaryotic and eukaryotic gut microbes. Historically, the role of these anaerobic obligate symbionts has been attributed to the nutritional welfare of the host. We provide evidence that protozoa (and/or their associated bacteria) colonizing the hindgut of the dampwood termite Zootermopsis angusticollis, synthesize multiple functional β-1,3-glucanases, enzymes known for breaking down β-1,3-glucans, the main component of fungal cell walls. These enzymes, we propose, may help in both digestion of ingested fungal hyphae and protection against invasion by fungal pathogens. This research points to an additional novel role for the mutualistic hindgut microbial consortia of termites, an association that may extend beyond lignocellulolytic activity and nitrogen fixation to include a reduction in the risks of mycosis at both the individual- and colony-levels while nesting in and feeding on microbial-rich decayed wood.

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