1612 Florida Entomologist 96(4) December 2013 VIRUS-LIKE SYMPTOMS IN A TERMITE (ISOPTERA: KALOTERMITIDAE) FIELD COLONY THOMAS CHOUVENC, AARON J. MULLINS, CAROLINE A. EFSTATHION AND NAN-YAO SU Department of Entomology and Nematology, Ft. Lauderdale Research and Education Center, University of Florida, Institute of Food and Agricultural Sciences, 3205 College Ave, Ft. Lauderdale, FL 33314, USA *Corresponding author; E-mail: [email protected] Researchers in the field of termite biological within a single branch of a small dead tree control have tried for decades to isolate and (unidentified).A ll individuals (≈30) were found formulate microbial agents that could spread dead within the gallery but their level of decom- within termite (Isoptera) groups so as to cre- position was not advanced, suggesting that all ate an epizootic event and achieve successful individuals died in a short time frame within biological control (Culliney & Grace 2000). The the past 24 h or so. Most individuals showed incentive to develop a so-called “environmen- a yellow milky color, and the head capsule and tally friendly” technology as an alternative to parts of the thorax were unusually dark brown chemical treatment resulted into unrealistic or black (Fig. 1). At the time of collection, the optimism and despite all the promising labora- rainy season had just started, with severe light- tory tests, no termite biological control technol- ning storms, a characteristic of Florida summer ogy was ever achieved (Chouvenc et al. 2011). weather (Hodanish et al. 1997). Hence, we first Although the original idea was to use self-rep- hypothesized that the tree or its surrounding licating entomopathogens that could be spread may have been hit by a lightning, killing the by social contact among individuals of the col- termite colony in the process, but no obvious ony, recent studies have shown the importance signs of such event (burn marks) were found of defense mechanisms within termite colonies in the area. Secondly, because some termite ca- that reduce the chance for entomopathogens davers were showing signs of bacterial growth, from spreading throughout the nest (Chouvenc we hypothesized that the colony may have suc- et al. 2008; Chouvenc & Su 2010; Hamilton et cumbed to a bacterial epizootic. We isolated 4 al. 2011). Because termites can prevent patho- strains of bacteria (Gram-rods, Gram + Cocco- gens from completing their life cycle within the bacillus, Gram + rods, Gram + Bacillus, identi- group, it was suggested that the traditional con- fication according to Holt et al. 1994) from the cept of an epizootic (Steinhaus 1949) could not cadavers, using a sterile cotton swab streaked be applied to termites (Chouvenc & Su 2012). on 1/5th strength potato dextrose agar. Pure iso- Paradoxically, while this field of study was lates were cultured in potato dextrose broth. In based on the assumption that an epizootic could absence of laboratory colonies of N. jouteli, we naturally occur in termites (Schmid-Hempel exposed groups of 20 termites (Coptotermes for- 1998), the occurrence of disease in termite mosanus Shiraki) in a 45-mm petri dish with groups was only observed under laboratory con- a wet cellulose pad on the bottom to a range ditions in highly artificial conditions or in the of concentrations of the microorganisms (106 to field using inundative control methods, which 109 cells applied on the cellulose pad), and ter- bypass the need for an epizootic (Chouvenc et mite groups were maintained for 15 d in labora- al. 2011). Therefore, to our knowledge, there tory conditions. None of the groups exposed to are no official reports about the occurrence of the bacteria showed significant mortality when any natural epizootic event in a termite colony compared to control groups (Cox proportional under field conditions. The absence of such ob- hazard regression analysis), and out of the few servations may be explained by the cryptic life individuals that died within the time frame, style of termites, as termite colonies are usually none showed signs of their head capsule turn- contained within a closed gallery system, and ing black. We suggest that all 4 bacteria were it can be difficult, if not impossible, for any ob- present in the termites’ body as saprophytes as server to have access to the colony at the precise previously observed (Chouvenc et al. 2012). Al- moment it is undergoing an epizootic event. Al- though our bioassay was performed on C. for- ternatively, natural epizootics in termites may mosanus only and a species-specific virulence be so rare that they simply never have been cannot be fully excluded, it is unlikely that such observed. The fact is, no natural epizootic in a bacteria were responsible for the sudden death termite colony has ever been reported. of the N. jouteli colony. On 11 Jun 2011, while prospecting for termite As we failed to show a case of bacterial epi- samples in forested areas of Broward County zootic within termite groups, and because of (Florida, USA), we encountered a small colony the apparent absence of mycosis in any of the of Neotermes jouteli (Banks) (Kalotermitidae) cadavers, we did not pursue the study further. Scientific Notes 1613 Fig. 1. Neotermes jouteli cadavers showing a dark-head syndrome. All individuals (≈ 30) from a single field colony were found dead, displaying this syndrome. Scale bar = 8 mm. It is only recently that we considered that the SUMMARY termites may have been infected by a viral agent. Levin et al. (1993) described the symp- The concept behind the use of biological con- toms of Reticulitermes flavipes (Kollar) exposed trol agents against termites was based on the to an entomopox virus, which was previously assumption that epizootic events can occur nat- isolated from a grasshopper (Melanoplus san- urally in a termite colony. However, no reports guinipes Stål; Orthoptera: Acrididae) in labo- ever mentioned the occurrence of epizootic in ratory conditions. The photograph and the natural field conditions in any termite species. description provided by Levin et al. (1993) We here describe what could be the first report match our own observations and suggest that of a viral epizootic in a field colony ofNeotermes the colony of N. jouteli we discovered may have jouteli. been killed by a viral epizootic. Unfortunately, Key Words: bacteria, entomopathogen, Koch’s and to our biggest disappointment, we realized postulates, Melanoplus sanguinipes, Reticuli- that the cadaver samples had not been stored termes flavipes properly, which prevented us from testing for the presence of such virus in our samples, and ultimately prove this hypothesis. Although we RESUMEN could not prove that the death of the Neotermes colony was caused by a viral agent, the symp- El concepto detrás de la utilización de agentes toms strongly indicated the presence of a virus de control biológico contra las termitas se basa en in these samples. The purpose of this study la suposición de que eventos de epizoóticas pueden was, first, to document the occurrence of a vi- ocurrir de forma natural en una colonia de ter- rus-like symptom in termites under field condi- mitas. Sin embargo, no se conocen informes que tions, as such observation was previously never hayan mencionado la aparición de epizoóticas en reported, and, second, to provide an incentive condiciones naturales de campo en especies de for future research if such symptoms are ob- termitas. Se describen lo que podría ser el primer served again to test for the presence of viruses informe de una epizoótia viral en el campo de una in termites. colonia de Neotermes jouteli. 1614 Florida Entomologist 96(4) December 2013 Palabras Clave: bacterias, entomopatógenos, CULLINEY, T. W., AND GRACE, J. K. 2000. Prospects postulados de Koch, Melanoplus sanguinipes, Re- for the biological control of subterranean termites ticulitermes flavipes (Isoptera: Rhinotermitidae), with special reference to Coptotermes formosanus. Bull. Entomol. Res. 90: 9-21. REFERENCES CITED HAMILTON, C., LAY, F., AND BULMER, M. S. 2011 Subter- ranean termite prophylactic secretions and external CHOUVENC, T., AND SU, N.-Y. 2010. 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