Aaron J. Mullins

NEW FLIGHT DISTANCE RECORDED FOR COPTOTERMES FORMOSANUS (ISOPTERA: RHINOTERMITIDAE)

The Formosan subterranean termite (FST), Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), was first introduced to New Orleans after World War II inside infested cargo returning from the Orient (La Fage 1987). For the past 60 years, they have spread throughout the New Orleans metro area, displaced native subterranean termite species, and significantly damaged buildings, trees, boats, and railroad ties in the process. To help combat the problem, the U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS) provided funding for treating buildings in a 50-block area of the French Quarter in New Orleans to determine if an area-wide subterranean termite control program is capable of reducing overall populations. Since 1998, populations have been reduced based on structural inspections, termite activity inside independent monitoring stations installed throughout the French Quarter, and the overall number of alates (winged reproductives) recovered from insect glue boards attached to streetlights throughout the French Quarter (Lax & Osbrink 2003). However, alates are still being captured in significant numbers inside selective areas of the French Quarter and along the borders of this treatment zone. Each year during May and June, untold numbers of male and female alates disperse throughout the area in the early evening and tend to congregate around light sources when present. Information on how far they are capable of flying from a dispersal point was virtually unknown, especially in a large urban area. During field observations in early 2004, it appeared that FST alates were flying across the Mississippi River with the aid of prevailing winds and into the French Quarter. To establish if alates were dispersing into the treatment zone from bordering areas, alates were marked with fluorescent visible powders (Shannon Luminous Materials, Inc., Santa Ana, CA) during two dispersal flights on different evenings at a selected site of known termite activity across the Mississippi River, located directly to the southeast of the French Quarter. In cooperation with USDA-ARS, 445 rectangular (20.7 cm × 10.2 cm) glue boards (TRAPPER® LTD, Bell Laboratories, Inc., Madison, WI) were attached to streetlights along the Riverwalk and throughout the French Quarter to capture potentially marked alates. The glue boards were positioned on the streetlights just below the lantern. Weather conditions, including wind velocity and direction, were recorded each evening with a hand-held weather station (Kestrel® 4000, Nielsen-Kellerman, Boothwyn, PA). Alates were individually marked with a bright orange fluorescent powder with a handheld commercial duster as they were flying in a north to northwest direction over the river. These alates were already in flight at the time of marking and their source could not be located. After marking, every glue board was removed and inspected with a UV black light. New glue boards were used for each dispersal flight event. On 1 June 2004, approximately 50 FST alates were initially marked and a single alate was recovered across the River on a glue board 771 m away (Fig. 1). Then, on 7 June, approximately 50 alates were marked again and two alates were recovered on glue boards 866 m and 892 m away (Fig. 1). The wind direction on 1 and 7 June was from the south and southeast at an average speed of 0.93 m/sec and 0.83 m/sec, respectively. Previously, a wind speed at or below 1.0 m/sec was shown to be one of the most important microenvironmental factors involved in determining dispersal flight activity (Leong et al. 1983).

Reinvasion and Colony Expansion of Coptotermes formosanus (Isoptera: Rhinotermitidae) After Areawide Elimination

ABSTRACT The population recovery of Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae) colonies were monitored after an areawide elimination of all detectable colonies from September 2003 to August 2005 in Louis Armstrong Park, New Orleans, LA. Six colonies reinvaded the vacant niche created by the full elimination. These colonies expanded their territories throughout the study period. This represented 43% of the original number of colonies present in the park before the elimination. To determine the mode of the reinvasion, nuptial pair establishment was monitored during the C. formosanus dispersal flight seasons. Nuptial pairs were discovered up to 1 yr after the elimination. Morphological and genetic data were collected from field colonies before the full elimination in 2002 and again in 2005 after the reinvasion of these territories by new colonies. These data were used to estimate the relative age of reinvading colonies as compared with their predecessors. It is proposed that the first three reinvading colonies detected were smaller colonies that were undetectable before the full elimination, or were older, established colonies present outside of the park, that expanded their foraging territories into the park in the absence of competition from the eliminated populations. The subsequent three colonies to reinvade seemed to be small colonies founded during or just before the study period by an imago pair after a dispersal flight into the park from outlying areas. The implications of this study on subterranean termite areawide integrated pest management strategies are discussed.

Dispersal Flights of the Formosan Subterranean Termite (Isoptera: Rhinotermitidae)

ABSTRACT The Formosan subterranean termite, Coptotermes formosanus Shiraki, is a pest of major economic concern. This termite is particularly known for its tendency to establish populations in nonendemic areas via maritime vessels as well as human-aided transport of infested materials. The natural spread of this species after new introductions occurs in part by dispersal flights originating from mature colonies. Dispersal flight activity is also the primary variable for the evaluation of area-wide management programs. Few studies exist describing the dynamics and distribution of a typical dispersal flight for this species. The present study used data collected by mark—recapture of C. formosanus alates over 12 individual evenings of dispersal flights in the New Orleans French Quarter. In this study, we found that for one selected flight dispersal location, which was not affected by a high density of trap locations nearby, alates flew on average 621m from their parent colony. A new record of a 1,300-m dispersal flight was recorded. Spatial analysis showed that neither wind nor light affected the direction of flight, which may, however, be attributed to scarce light and wind measurements in the study region.

Foraging Distance and Population Size of Juvenile Colonies of the Formosan Subterranean Termite (Isoptera: Rhinotermitidae) in Laboratory Extended Arenas

Abstract The relationship between colony size and foraging distance was examined in extended foraging arenas with juvenile colonies of the Formosan subterranean termite, Coptotermes formosanus Shiraki. Our results showed that as long as royal pairs are present, larger colonies foraged at longer distances, and the oldest workers distributed farther away from the central nest. The results agree with the scaling model that predicts a large foraging range for animals of larger body size. An analysis of published data from population survey studies and field trials of bait toxicants showed that field colonies of the eastern subterranean termite, Reticulitermes flavipes (Kollar), follow the scaling model, while C. formosanus colonies were inconsistent with the model prediction. Reasons for the inconsistency with field data of C. formosanus are discussed.

Flight Phenology of Two Coptotermes Species (Isoptera: Rhinotermitidae) in Southeastern Florida

Abstract The dispersal flight activity (“swarming”) of two invasive subterranean termite species, Coptotermes gestroi (Wasmann) and Coptotermes formosanus Shiraki, was monitored in metropolitan southeastern Florida, where both species are now sympatric and major structural pests. Historical records of alates collected in the area showed that the two species have distinct peaks of flight activity, from mid-February to late April for C. gestroi, and from early April to late June for C. formosanus. However, an overlap of the two dispersal flight seasons has been observed since at least 2005. The daily monitoring of dispersal flight events in southeastern Florida in 2014, 2015, and 2016 confirmed that simultaneous flights occurred several times each year. In addition, environmental conditions for favorable flights were identified, and it was established that low temperature was the primary factor inhibiting both species from dispersal flights, while all other factors had little impact on the occurrence of major dispersal flight events. However, both species shared similar temperature requirements for favorable dispersal flight conditions despite distinct peaks of activity over time. The analysis of sex ratios and average weights of the alates suggests that intrinsic colony factors are important for the timing of the maturation of alates, and that once a cohort of individuals is ready to disperse, a flight may occur as soon as the environmental conditions are favorable.

Territorial Status-Quo Between the Big-Headed Ant (Hymenoptera: Formicidae) and the Formosan Subterranean Termite (Isoptera: Rhinotermitidae)

Abstract The big-headed ant, Pheidole megacephala (Fabr.) (Hymenoptera: Formicidae) and the Formosan subterranean termite, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae) are 2 invasive species in south Florida, and both have a major economic and ecological impact. Because both species are often associated with man-made structures, we investigated how the 2 species interacted when their tunneling system connected, to determine if the big-headed ant had the ability to predate or displace subterranean termite colonies. It was previously suggested that the 2 species had a predator-prey interaction. However in this study we showed that C. formosanus can defend its territory against P. megacephala with minimal loss, and we therefore re-described their interaction as a status quo for habitat competition. It is unlikely that a competitive displacement would take place between C. formosanus and P. megacephala because of their ability to successfully defend their respective nests.

Molting Site Fidelity in Workers of Formosan Subterranean Termites (Isoptera: Rhinotermitidae)

Abstract Spatial assessment of molting in workers of Coptotermes formosanus Shiraki was conducted in laboratory-reared colonies using extended foraging arenas. Workers at a premolt stage were found concentrated in the nest or in a planar arena near the nest. However, molting individuals were found exclusively in the central nest and they stayed inside or near the central nest for at least 36 h postmolting.The absence of premolt workers at foraging sites suggests that the workers have an affinity to the nest for molting and the second study on nest-fidelity evaluation suggested that the workers molt in the proximity of eggs.The molting site fidelity by workers in a colony ensures that speeding up the time for mortality induced by chitin synthesis inhibitor (CSI) baits will not result in an inhibitory cascade of dead termites around the bait stations. Thus, speeding up the elimination of a C. formosanus colony using CSI baits with the addition of molt-accelerating compounds will not lead to secondary repellency. Reasons for the molting-site fidelity amongst workers in a colony are discussed.

Reinvasion Dynamics of Subterranean Termites (Isoptera: Rhinotermitidae) Following the Elimination of All Detectable Colonies in a Large Area.

Abstract Following the elimination of all detectable termite colonies in the 32-acre Louis Armstrong Park in New Orleans, LA, in 2002–2003, termite activity was monitored by using 808 Sentricon stations. Between January 2004 and July 2005, termites were found in 8–11 stations. In August 2005, the Park was flooded by Hurricane Katrina, but termites remained active. Post-Katrina termite activity levels of 16–21 stations were recorded throughout 2006, and in October 2007, the activity drastically increased to 43 stations. This rapid increase of termite activity continued into 2008, and a total of 94 stations harbored termite activities by July 2008. Termite activity peaked at 109 stations in September 2008 and then leveled down to 64 stations in March 2009. Termite activity in the Park between 2004 and 2009 was described by a Sigmoid model with a carrying capacity of 76 stations, and a Sigmoid mid-point of 1,202 d. In April 2009, a total of 14 colonies of Coptotermes formosanus Shiraki and one colony of Reticulitermes flavipes (Kollar) were delineated by using microsatellite genotyping and mark–recapture protocol. Of the 15 colonies, eight near the Park border probably originated from existing colonies from outside, and seven C. formosanus colonies found inside the Park were probably initiated by alate pairs. Our results showed that, if surrounded by high population pressure of termites and no control measures are applied, an area cleared of termite populations by baits can be completely re-populated by termites from outside in 53 mo.

Rare Production of Nymphs in an Asian Subterranean Termite (Isoptera: Rhinotermitidae) Incipient Colony

Summary Coptotermes colonies usually produce nymphs when a colony reaches maturity. In this study, we describe a rare case of nymph production from a 10-mo-old colony that previously had lost a primary reproductive. Such replacement reproductives are not functional. We suggest that the unusual developmental plasticity we observed may be the result of a vestigial developmental pathway that may partially regain its functionality in mature colonies.

Virus-Like Symptoms in a Termite (Isoptera: Kalotermitidae) Field Colony

The concept behind the use of biological control agents against termites was based on the assumption that epizootic events can occur naturally in a termite colony. However, no reports ever mentioned the occurrence of epizootic in natural field conditions in any termite species. We here describe what could be the first report of a viral epizootic in a field colony of Neotermes jouteli . El concepto detras de la utilizacion de agentes de control biologico contra las termitas se basa en la suposicion de que eventos de epizooticas pueden ocurrir de forma natural en una colonia de termitas. Sin embargo, no se conocen informes que hayan mencionado la aparicion de epizooticas en condiciones naturales de campo en especies de termitas. Se describen lo que podria ser el primer informe de una epizootia viral en el campo de una colonia de Neotermes jouteli . View this article in BioOne