Asian Subterranean Termite Research Articles

A comparison between above-ground bait stations and experimental caulk baits for elimination of field colonies of the Asian subterranean termite, Coptotermes gestroi (Blattodea: Rhinotermitidae).

Survey stakes and in-ground (IG) stations have failed to intercept underground tunnels of the Asian subterranean termite, Coptotermes gestroi (Wasmann), in southeastern Florida, rendering nearly useless the IG bait station that is the main tool of commercial baiting systems. When placed over an active infestation, above-ground (AG) bait stations were readily fed on by C. gestroi, resulting in colony elimination. A new experimental type of AG bait application being studied is an injectable caulk bait. In this study, we compared the efficacy of AG bait stations and an experimental AG caulk bait against field colonies of C. gestroi. Following the applications of AG bait stations at 3 sites with infested houses and trees, C. gestroi colonies were eliminated 7.1-28.1 wk later. The experimental AG caulk bait was applied at 7 sites including 4 houses, 2 office buildings, and 1 docked sailboat. Colony elimination times at caulk bait sites ranged from 3.1 to 13.6 wk, but there was no statistical difference in mean colony elimination time between AG station bait sites (17.4 ± 10.5 wk) and AG caulk bait sites (8.4 ± 3.8 wk). This study showed that AG caulk bait applications were equally efficacious in eliminating existing C. gestroi in structures as AG bait stations and will offer another tool for termite control professionals to better manage subterranean termites including C. gestroi.

From establishment to dominance: spatio-temporal infestation patterns of the Asian subterranean termite, Coptotermes gestroi, in Key West, Florida, 1999–2021

From establishment to dominance: spatio-temporal infestation patterns of the Asian subterranean termite, Coptotermes gestroi, in Key West, Florida, 1999–2021

A comparison of tunnel geometry between the Formosan subterranean termite and the Asian subterranean termite (Blattodea: Rhinotermitidae).

Stake surveys and in-ground monitoring stations have been widely used to study field populations of many subterranean termite species, but thus far they have never been intercepted by the invasive Asian subterranean termite, Coptotermes gestroi (Wasmann), in southeastern Florida. To investigate the reasons for the inability of C. gestroi to intercept these in-ground monitoring devices, we compared its tunnel geometry with that of the Formosan subterranean termite, Coptotermes formosanus Shiraki. Two-year-old incipient colonies of both species confined in simulated structural infestations were connected to planar arenas containing four wooden discs. Coptotermes formosanus colonies constructed more abundant and more complex tunnel networks and intercepted more wooden discs than C. gestroi. C. formosanus propagated shorter primary tunnels and longer secondary tunnels with more branching frequency than C. gestroi, and probably adopted an area searching strategy to search for food in an area before moving on to other areas. In comparison, C. gestroi used a distance searching strategy by constructing linear and long primary tunnels to search for food at distance. Because tunnels of C. gestroi were less abundant and they tend to travel straight for some distance, they may have bypassed survey stakes or in-ground monitoring stations that are sparsely distributed in soil. The tunnel geometry of C. gestroi may explain why none of these in-ground monitoring devices has been intercepted by this species in southeastern Florida. © 2023 Society of Chemical Industry.

Elimination of structural and tree infestations of the Asian subterranean termite, Coptotermes gestroi (Wasmann) (Blattodea: Rhinotermitidae) with noviflumuron baits in above-ground stations.

The traditional stake survey and in-ground (IG) monitoring stations have been ineffective in aggregating the Asian subterranean termite, Coptotermes gestroi (Wasmann) in southeastern Florida. In this study, we used both IG and above-ground (AG) Sentricon stations to monitor and bait C. gestroi, and as expected, none of the 83 IG stations was intercepted. Despite this, AG bait stations with 0.5% noviflumuron were successfully used to eliminate C. gestroi colonies. From 2 field experiments, the mean colony elimination time (±SD) using AG baits were 6.4 ± 3.8 wk (n = 4) and 8.0 ± 2.1 wk (n = 12), respectively. Such results were compatible with baiting studies against field colonies of C. gestroi elsewhere, that is, 4-9 wk. The successful rates in monitoring and baiting of C. gestroi with IG stations in other regions also varied, which may be due to the variabilities in tunnel geometry of this species in different environments. In areas with established C. gestroi populations, routine inspection for signs of activity in structures and surrounding trees can be a critical component for pest control providers for early detection of infestation and colony elimination with AG bait stations.

Methods for Collecting Large Numbers of Exuviae from Coptotermes (Blattodea: Rhinotermitidae) Termite Colonies

The nutritional properties of subterranean termite exuviae (shed exoskeletons) are not well-known because obtaining the large quantities necessary for investigation is difficult. A method for collecting large numbers of exuviae is reported here for the Asian subterranean termite, Coptotermes gestroi (Wasmann) (Blattodea: Rhinotermitidae), an invasive and economically important tropical termite species. In this study, groups of 1,000 C. gestroi workers from 4-yr-old laboratory colonies (n = 3) were allowed to feed on a media pad dyed with Nile Blue A for 2 d. Approximately 16% of the original 1,000 workers did not uptake dye. These individuals were then placed into a Petri dish with dyed filter paper and checked hourly (10:00 A.M. to 10:00 P.M.) for 7 d. Newly molted workers and those individuals that started turning blue were removed to prevent feeding on exuviae. An average of 14 workers molted per d that yielded an average of 12 exuviae with an overall mean of 86 exuviae collected over the 7 d study period. We also found the number of individuals that acquired dye during the study significantly decreased by d. However, variables such as the number of exuviae, newly molted individuals, and cadavers were not correlated with d of collection because termites molt asynchronously.

Courtship Behavior Confusion in Two Subterranean Termite Species that Evolved in Allopatry (Blattodea, Rhinotermitidae, Coptotermes).

Congeneric species that live in sympatry may have evolved various mechanisms that maintain reproductive isolation among species. However, with the spread of invasive organisms owing to increased global human activity, some species that evolved in allopatry can now be found outside their native range and may have the opportunity to interact, in the absence of mechanisms for reproductive isolation. In South Florida, where the Asian subterranean termite, Coptotermes gestroi (Wamann), and the Formosan subterranean termite, Coptotermes formosanus Shiraki (Blattodea: Rhinotermitidae) are invasive, the two species can engage in heterospecific mating behavior as their distribution range and their dispersal flight season both overlap. Termites rely on semiochemicals for many of their activities, including finding a mate after a dispersal flight. In this study, we showed that females of both species produce (3Z,6Z,8E)-dodeca-3,6,8-trien-1-ol (DTE) from their tergal glands as a shared sex pheromone. We suggest that both species primarily rely on an inundative dispersal flight strategy to find a mate, and that DTE is used as a short distance pheromone or contact pheromone to initiate and maintain the tandem between males and females. The preference of C. gestroi males for C. formosanus females during tandem resulted from the relatively high amount of DTE produced by tergal glands of C. formosanus females, when compared with those of C. gestroi females. This results in confusion of mating in the field during simultaneous dispersal flights, with a potential for hybridization. Such observations imply that no prezygotic barriers emerged while the two species evolved in allopatry for ~18Ma.

Evaluation of the virulence of entomopathogenic fungus, Isaria fumosorosea isolates against subterranean termites Coptotermes spp. (Isoptera: Rhinotermitidae)

The entomopathogenic fungus Isaria fumosorosea Wize, formerly known as Paecilomyces fumosoroseus is reported as a promising biocontrol agent for controlling subterranean termites, particularly those belonging to the family Rhinotermitidae. In Malaysia, the family Rhinotermitidae includes two species of subterranean termites with extremely high economic importance; namely Coptotermes curvignathus Holmgren, and the Asian Subterranean Termite (Coptotermes gestroi Wasmann). To comprehend the potential control of this soil-dwelling fungus against these subterranean termites in Malaysia, an investigation was carried out by testing the pathogenecity of 11 isolates against these termite species. All isolates showed pathogenic potential against the termite (Mortality rate of C. curvignathus: 84.4%; C. gestroi: 67.3%). Isolate PF49 was the most effective against both species of termites and was further tested for its virulence and mycosis. The LC50 values of PF49 against C. curvignathus and C. gestroi were 7.55 × 103 and 1.09 × 102 conidia/ml, respectively. The average number of days required to complete the mycosis process in C. curvignathus and C. gestroi were 4.7 and 8 days, respectively. These fungi are believed useful for protecting living trees, plants, wood, wood structures, and other cellulosic materials susceptible to termite infestation and damage.

Coptotermes gestroi(Wasmann) (Blattodea [Isoptera]: Rhinotermitidae), a Threat to the Southeastern Florida Urban Tree Canopy

In addition to being a structural pest, the Asian subterranean termite, Coptotermes gestroi (Wasmann) (Blattodea [Isoptera]: Rhinotermitidae), appears to be a serious pest of the native urban tree canopy of southeastern Florida. Asian subterranean termite colonies have the ability to cause feeding damage to a wide range of trees comprising the urban canopy, some potentially to a lethal level. Slash pine, Pinus elliottii Engelm. (Pinaceae), appears to be particularly susceptible to C. gestroi feeding damage, as the termites feed primarily on the outer layers of the wood, immediately beneath the bark, wounding live tissues and ultimately girdling the tree. In comparison, hardwood trees such as live oak, Quercus virginiana Mill. (Fagaceae), sustain damage to the heartwood at the center of the tree, resulting in a central cavity, but leaving the live tissue intact. Our results suggest that C. gestroi has the potential to kill pine trees within the local urban canopy, which may irreversibly alter the urban forest composition. In addition, many large trees in our survey have been consumed partially by mature C. gestroi colonies, potentially compromising their structural integrity. Some large oak trees that were extensively hollowed out by C. gestroi collapsed in 2017 during hurricane Irma. We discuss different potential approaches for protecting susceptible trees, as a comprehensive IPM strategy is needed for this invasive termite pest species, especially in the complex and extensive urban forest of southeastern Florida.

Fipronil enhanced natural occurrence of Fusarium solani (Hypocreales: Nectriaceae) on building infesting termite Heterotermes indicola Wasmann (Blattodea: Rhinotermitidae)

Abstract The Southeast Asian subterranean termite, Heterotermes indicola Wasmann (Blattodea; Rhinotermitidae), is recognized as a building infesting lower termite species in urban environment. The extensive use of chemical termiticides against aerial mud tubes and underground nests of H. indicola beneath the buildings could not suppress its infestation; however, it enhanced the environmental contamination and insecticide resistance. In the present study, we tried to control termites using naturally occurring entomopathogenic fungi Fusarium solani (Mart.) Sacc., along with sublethal concentrations of termiticide fipronil in no-choice feeding pathogenecity bioassay for 20 days. Termite mortality after 20 days of continuous exposure to highest fungal treatment 1 × 109 conidia/mL was 10% exclusively, whereas 100% mortality was calculated just after 16 days of concurrently exposure to 5 ppm of fipronil and highest rate of fungus 1 × 109 conidia/mL. These results indicated that insecticidal stress declined the immune response of termites and reduced the repellency of termites against fungal conidia by breaching the primary defense mechanism (allogrooming). This co-application of F. solani at suitable sublethal concentrations of fipronil showed the promising potential against termites that may reduce the selection pressure of pesticides and resistance risk by targeted pests, but further investigations are necessary for developing field trials.

Potential Hybridization between Two Invasive Termite Species, Coptotermes formosanus and C. gestroi (Isoptera: Rhinotermitidae), and Its Biological and Economic Implications.

The Asian subterranean termite, Coptotermes gestroi, is a tropical species but has increasingly been collected from the subtropics in recent years, making it sympatric to the Formosan subterranean termite, C. formosanus in at least three areas, Taiwan, Hawaii, and Florida. Simultaneous flights by these two species were observed since 2013 in South Florida, during which interspecies tandems were observed. Laboratory mating of C. formosanus and C. gestroi alates produced hybrid incipient colonies of larger population size. Studies are underway to examine the presence in the field of hybrid colonies in sympatric areas of Taiwan and Florida. Other biological characteristics of C. formosanus × C. gestroi hybrids being studied include temperature tolerance and preference, colony growth rate, wood-consumption rate, and reproductive fertility. This current research aims to determine the potential establishment of a hybrid termite population in south Florida and Taiwan. It investigates the risk of introgressive hybridization in field populations, with an emphasis on its potential ecological, evolutionary, and economic consequences.

Proliferation of the Invasive TermiteCoptotermes gestroi(Isoptera: Rhinotermitidae) on Grand Cayman and Overall Termite Diversity on the Cayman Islands

The Asian subterranean termite, Coptotermes gestroi (Wasmann) (Isoptera: Rhinotermitidae), was discovered on Grand Cayman Island in 2000 and, by 2014, had been recorded from 102 land-based localities. These data were used in a hierarchical cluster analysis to identify homogeneous clusters of sites to estimate separate introduction points on the island. Results suggest 4 separate introductions of C. gestroi to Grand Cayman by boat and 1 by land transport from other previously infested parts of the island. The infestations by boat could be either primary introductions (originating from another island) or secondary introductions (originating from other previously infested parts of Grand Cayman). An individual-based model was used to simulate non-anthropogenic spread of C. gestroi over Grand Cayman from 2014 to 2050. The model predicts that by 2050, most of the western part of Grand Cayman will likely be heavily infested by C. gestroi, whereas patches of unsuitable habitat restrict the expansion of the species over the central and eastern parts of the island. In the absence of further human introductions, it will likely take a century for C. gestroi to saturate the island by natural dispersal only. Based on detailed termite diversity surveys, we provide updated records for 14 termite species, collectively, on Grand Cayman, Little Cayman, and Cayman Brac.

Haplotype-habitat associations of Coptotermes gestroi (Termitoidae: Rhinotermitidae) from mitochondrial DNA genes.

Coptotermes gestroi (Wasmann) or the Asian subterranean termite is a serious structural pest in urban settlements in Southeast Asia that has been introduced to other parts of the world through human commerce. Although mitochondrial DNA markers were previously used to shed light on the dispersal history of the Asian subterranean termite, there were limited attempts to analyze or include populations of the termite found in the wild in Southeast Asia. In this study, we analyzed the 16S ribosomal RNA (16S rRNA) and cytochrome c oxidase subunit 1 (cox1) genes of Asian subterranean termite colonies found in mangrove swamps, beach forests, plantations, and buildings in semi-urban and urban areas to determine the relationship between colonies found in the wild and the urban habitat, and to investigate the possibility of different ecotypes of the termite in Peninsular Malaysia. Our findings show that the 16S rRNA haplotypes recovered from this study clustered into eastern, western, and southern populations of the termite, while the cox1 haplotypes were often specific to an area or site. The 16S rRNA and cox1 genes or haplotypes showed that the most abundant haplotype occupied a wide range of environments or habitats. In addition, the cox1 tree showed evidence of historical biogeography where basal haplotypes inhabited a wide range of habitats, while apical haplotypes were restricted to mangrove swamps and beach forests. Information on the haplotype-habitat association of C. gestroi will enable the prediction of habitats that may harbor or be at risk of invasion in areas where they have been introduced.

Termite resistance and physico-mechanical properties of particleboard using waste tobacco stalk and wood particles

The study investigated the termite resistance, physical and mechanical properties of particleboard made from waste tobacco (Nicotiana tabacum L.) stalk and Paraserianthes falcataria wood particles. Boards containing at least 25% tobacco stalk exhibited excellent termite resistance in laboratory no-choice feeding test against the Asian subterranean termite, Coptotermes gestroi Wasmann. Underground ground field exposure tests also showed that particleboard containing at least 50% tobacco stalk provided excellent protection against Philippine subterranean termites. Termite resistance of particleboard containing tobacco stalk is most likely due to the presence of residual nicotine in the samples. Addition of P. falcataria wood particles in all proportions used in this study resulted in boards with internal bond, stiffness and strength properties above the minimum set by the European standard EN 312-2 (1996) for general use particleboards. Boards containing 50–100% tobacco stalk showed high water absorption and thickness swelling after 24 h soaking in water. Results of the study showed that tobacco stalk can be used as an alternative material either alone or in combination with wood particles for the manufacture of particleboard with direct positive impact on disposal problem and efficient utilization of this waste biomass.

The Role of Geographic Information Systems for Analyzing Infestations and Spread Of Invasive Termites (Isoptera: Rhinotermitidae And Termitidae) in Urban South Florida§

The ability to manage geospatial data has made Geographic Information Systems (GIS) an important tool for a wide range of applications over the past decades, including management of natural resources, analysis of wildlife movement, ecological niche modeling, or land records management. This paper illustrates, using invasive termite species as examples, how GIS can assist in identifying their potential sources of infestations and model their spread in urban South Florida. The first case study shows that the Formosan subterranean termite, Coptotermes formosanus Shiraki, and the Asian subterranean termite, Coptotermes gestroi (Wasmann) (Isoptera: Rhinotermitidae), were introduced into and dispersed across South Florida by sailboats and yachts. The second case study shows an agent-based model to simulate the natural spread of Nasutitermes corniger (Motschulsky) (Isoptera: Termitidae) in Dania Beach, Florida. This paper provides an overview of basic functionalities in GIS and demonstrates how they can be customized for advanced modeling and simulation.

Effects of termiticide exposure on mutual interactions between the treated and untreated workers of the Asian subterranean termiteCoptotermes gestroi

Mutual interactions, including reciprocal food sharing and grooming between chlorantraniliprole- and fipronil-treated, and untreated Asian subterranean termites, Coptotermes gestroi (Wasmann), were examined using rubidium as a tracer. Two questions were addressed in this study: (1) After insecticide treatment, does the mutual interaction between termiticide-treated termites and untreated nestmates increase? (2) Does the nutritional status of both termiticide-treated termites and untreated nestmates affect the mutual interaction? The comparative data suggested that chlorantraniliprole-treated termites were more regularly attended by untreated termites than the fipronil-treated termites. Mutual interaction between the chlorantraniliprole-treated termites and untreated termites was not affected by their nutritional status. A high level of rubidium was present in the reciprocal exchange from fipronil-treated termites to starved untreated termites, indicating that intoxication induced alimentary or anal fluids served as a food source for starved termites. The results of the present study indicated that termites exposed to chlorantraniliprole were more likely to cease feeding and then undergo starvation. Thus, the treated termites were subject to intensive reciprocal food exchange and frequent attention from untreated nestmates. In the fipronil treatment, starvation status facilitated the reciprocal food exchange rate from treated termites to starved untreated termites.

Tunnelling behaviour of the Asian subterranean termite in heterogeneous soils: presence of cues in the foraging area

Exploitation of the environment by building a tunnel network is one of the stages involved in the foraging behaviour of subterranean termites, and it may be influenced by several factors, such as temperature, soil, drought, floods, predators, competitors, obstacles or even a lack of food. Because soils in natural environments are generally very heterogeneous, our aim in the present study was to analyse the tunnelling behaviour of the Asian species Coptotermes gestroi in the presence of physical, chemical and biological cues in the substrate (twisted wire, a pre-existing tunnel and a tunnel containing three dead soldiers of Heterotermes tenuis or C. gestroi ) in bidimensional glass arenas. All experiments were run in Biochemical Oxygen Demand incubator (25 ± 0.2 °C), and the arenas were digitally photographed after 24 h. Fewer primary tunnels were constructed in the absence of guidelines (control treatments) than in the presence of guidelines (experimental treatments), demonstrating more vigorous initial tunnelling behaviour in the presence of guidelines in the soil. In addition, termites in experimental treatments either clearly followed the solid guideline in several regions of the tunnelling arena, or spread their network of tunnels from the preformed excavation, and their tunnelling patterns differed from those of the controls. Finally, foragers usually avoided contact with dead soldiers by constructing primary tunnels at different sites from those where dead soldiers had been placed. These results indicate that behavioural patterns of C. gestroi foragers are altered when tunnelling substrates are not homogeneous.

Genetic Variation inCoptotermes gestroi(Isoptera: Rhinotermitidae) Populations from Hainan, Taiwan, and the Philippines1

The Asian subterranean termite, Coptotermes gestroi (Isoptera: Rhinotermitidae), is an important structural pest in southeast Asia, and it has invaded many regions of the world. Based on the combination of partial mitochondrial sequences of COII and 16S rRNA, phylogenetic analysis and genetic variation of C. gestroi populations from Hainan Island, Taiwan, and its native range were analyzed. The results showed that C. gestroi population from Hainan Island were closely related to those from Taiwan and the Philippines in southeast Asia. Analysis of molecular variance (AMOVA) revealed that most of the genetic variation resided among geographical populations (82.8%), and Hainan, Taiwan, and the Philippines populations may form a single geographical group. The results suggested that C. gestroi has successfully on Hainan Island, and the Hainan population was likely introduced from the Philippines by humans.

Preferences of Coptotermes formosanus Shiraki and Coptotermes gestroi (Wasmann) (Blattodea: Rhinotermitidae) among Three Commercial Wood Species.

The Formosan subterranean termite, Coptotermes formosanus Shiraki, and the Asian subterranean termite, Coptotermes gestroi (Wasmann), are both pests of wood in service in Hawaii and Florida. We conducted a laboratory study using method modified from those described in standard E1-09 of the American Wood Protection Association (AWPA 2009) to assess the termite resistance of three commercially available wood species used in regions of the USA where both termite species occur: Douglas fir, Pseudotsuga menziessii, southern yellow pine, Pinus spp. and redwood, Sequoia sempervirens. A multiple-choice (three-choice) assay was used for four weeks (28 days) in order to simulate field conditions of food choice and assess termite feeding preferences under 28 °C and 72–80% RH. 400 termites (360 workers: 40 soldiers) were released into each test jar. Five replicates and two controls of each wood species were used with each termite species. Termite mortality was recorded at the end of the test; and wood wafers were oven-dried and weighed before and after termite exposure to determine the mass loss due to termite feeding, and rated visually on a 0 (failure) to 10 (sound) scale. There were significant differences in mean mass loss values among the three wood species and between two termite species. The mean mass loss value for redwood was significantly lower than Douglas fir and southern yellow pine with both termite species. However, C. formosanus showed increased feeding on Douglas fir and southern yellow pine compared to C. gestroi.

Termite Resistant Properties of Sisal Fiberboards.

A study was carried out to test sisal (Agave sisalana Perrine) fiberboards properties as building materials against Asian subterranean termite, Coptotermes gestroi (Wasmann). Evaluation was in the laboratory according to the JWPA Standard-TW-S.1-1992. To improve mechanical properties of fiberboards made from sisal fibers, the boards were overlaid by rubber veneer, betung bamboo matting or formica. Result showed that the formica-overlaid sisal fiberboards performed better than other overlaid fiberboards against C. gestroi.

Analysis of the workers head transcriptome of the Asian subterranean termite, Coptotermes gestroi

The lower termite, Coptotermes gestroi (Isoptera: Rhinotermitidae), is originally from Southeast Asia and has become a pest in Brazil. The main goal of this study was to survey C. gestroi transcriptome composition. To accomplish this, we sequenced and analyzed 3003 expressed sequence tags (ESTs) isolated from libraries of worker heads. After assembly, 695 uniESTs were obtained from which 349 have similarity with known sequences. Comparison with insect genomes demonstrated similarity, primarily with genes from Apis mellifera (28%), Tribolium castaneum (28%) and Aedes aegypti (10%). Notably, we identified two endogenous cellulases in the sequences, which may be of interest for biotechnological applications. The results presented in this work represent the first genomic study of the Asian subterranean termite, Coptotermes gestroi.