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An overview of the development of termite baits in the past 3 decades
Abstract
Since the commercialization in 1995, termite baits have been introduced in 32 countries, protecting over 3.7 million homes and reducing pesticide use by more than 11,100 metric tons. Over the past 3 decades, advancements have been made to address the limitations of bait systems, including improvements in bait toxicants, bait matrices, and the frequency of required site visits. Termite baits have been applied in both commercial and experimental area-wide projects. This article discusses the factors contributing to the success of these projects and the key elements driving the progress and advancements in termite bait technology.
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Simple Summary: Subterranean termites cause damage to man-made structures around the world and are continuing to invade new areas. Current practices for controlling termites generally target a single colony as workers tunnel near these structures, and although they are effective in most instances, they never reduce the overall termite pressure in the surrounding area. An area-wide approach to pest management could offer a way of controlling termites at the population level. By eliminating all or most of the colonies within a given area, the threat of infestation decreases. We tracked individual termite colonies over time, before and after the introduction of termite baits, to assess how long these colonies remained active to determine if a termite-free area could be maintained with continued baiting. This baiting approach was successful in significantly reducing the overall termite population within a baited area. Abstract: We investigated the use of termite baiting, a proven system of targeted colony elimination, in an overall area-wide control strategy against subterranean termites. At two field sites, we used microsatellite markers to estimate the total number of Reticulitermes colonies, their spatial partitioning , and breeding structure. Termite pressure was recorded for two years before and after the introduction of Trelona ® (active ingredient novaluron) to a large area of one of the sites. Roughly 70% of the colonies in the treatment site that were present at the time of baiting were not found in the site within two months after the introduction of novaluron. Feeding activity of the remaining colonies subsequently ceased over time and new invading colonies were unable to establish within this site. Our study provides novel field data on the efficacy of novaluron in colony elimination of Re-ticulitermes flavipes, as well as evidence that an area-wide baiting program is feasible to maintain a termite-free area within its native range.
Termite infestations in urban areas are a serious problem because they cause negative economic effects, reduce the aesthetic value of buildings, damage crops, and require household repairs. Chemical controls are the most common method used against subterranean termites, and baiting has emerged as one of the prominent control methods. The goal of this research was to determine the efficacy of termite baiting by treating one of six active termite stations (selective baiting) with chlorfluazuron baits to eradicate six populations of subterranean termites. This work shows that the placement of chlorfluazuron baits in one of the active stations was sufficient to destroy a colony that was interconnected with multiple chlorfluazuron-free stations. In general, it requires an average of 4-8 weeks for a quantity of less than 300 g of chlorfluazuron bait to remove a termite infestation at the study site.
Termite baits containing 0.10% chlorfluazuron mixed in alpha cellulose powder was evaluated against the Asian subterranean termite, Coptotermes gestroi Wasmann (formerly Coptotermes vastator Light) (Blattodea: Rhinotermitidae), in wood structures exclusively using above-ground bait (AG) stations. Wood structures with active infestations of C. gestroi were selected and baited from January to April 2016. Termite colonies from all test sites were successfully eliminated after 8-12 wk of baiting. All sites were further monitored for the next three consecutive months and no sign of either termite recovery or re-infestation of a different colony was detected. Successful elimination of C. gestroi infestation in structures using only AG stations indicated that in-ground bait stations (IGs) may not be necessary for successful termite baiting in the Philippines. Changes in termite baiting protocols in tropical countries are proposed to reduce the cost of baiting in the Philippines and other Southeast Asian countries.
Site fidelity by molting termites in Formosan subterranean termite, Coptotermes formosanus Shiraki colonies is a new addition to our understanding of lower termites’ behavior and biology. Our previous studies indicated that workers moved to the central nest to molt in the presence of eggs and reproductives. The current study showed that noviflumuron-affected workers also return to the central nest and died in the vicinity of reproductives and eggs. The aversion to the dead and decaying workers caused reproductives and brood to leave the original central nest site in a colony and refuge
at newer sites every few days in response to newly dead workers near them. Because mortality was an event observed only in workers undergoing molting under the effect of noviflumuron- a CSI, the death of molting individuals was observed only around reproductives and brood. This study reveals a previously undiscovered behavior of molting termites and the mechanics behind a successful arsenal; noviflumuron baits used against subterranean termites.
The efficacy of bistrifluron termite bait was evaluated using in-ground bait stations placed around Coptotermes lacteus mounds in south-eastern Australia during late summer and autumn (late February to late May 2012). Four in-ground bait stations containing timber billets were placed around each of twenty mounds. Once sufficient numbers of in-ground stations were infested by termites, mounds were assigned to one of four groups (one, two, three or four 120 g bait canisters or 120 to 480 g bait in total per mound) and bait canisters installed. One mound, nominally assigned treatment with two canisters ultimately had no termite interception in any of the four in-ground stations and not treated. Eighteen of the remaining 19 colonies were eliminated by 12 weeks after bait placement, irrespective of bait quantity removed (range 43 to 480 g). Measures of colony decline-mound repair capability and internal core temperature-did not accurately reflect the colony decline, as untreated colonies showed a similar pattern of decline in both repair capability and internal mound core temperature. However, during the ensuing spring-summer period, capacity to repair the mound was restored in untreated colonies and the internal core temperature profile was similar to the previous spring-summer period which indicated that these untreated colonies remained healthy.
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.
Durable baits, Recruit HD, were installed in 45 Sentricon stations between September 2010 and July 2014 in the 32-acre Armstrong Park, New Orleans. After eliminating all detectable termite colonies in the Park, 6-12 mo elapsed before new activity was detected. Newly invading termite colonies were usually found near the Park border or were smaller colonies that originated from recently paired alates. After colony elimination, Recruit HD baits were left in the stations to intercept newly invading colonies of subterranean termites, leading to their elimination, and multiple cycles of such interception and elimination events were recorded. Because the presence of Recruit HD baits continues to eliminate incoming colonies with little effort in maintaining and resupplying baits in the target areas, the bait system offers an economically sustainable option for managing subterranean termite populations in a large area. The 32-acre Armstrong Park is a manageable size to carry out an area-wide (AW) project. If the number of such AW projects is gradually increased over time in selected metro areas of New Orleans, we predict that we may be able to turn the tide against the ever-increasing populations ofC. formosanusin the entire city.
In termites, it is challenging to recognize the incidence of molting in workers because of their successive stationary molt, asynchronous molting among individuals, cryptic behavior, a soft and poorly sclerotized cuticle, and they immediately consume the shed exuvia of nestmates. This study describes a method in which the degree of sclerotization of the mouthparts in newly molted workers of the Formosan subterranean termite can be quantified and used to determine if an individual has recently molted, within a 36-h time frame. Changes in the tanning of mouthparts over time were used as a measure of the index of sclerotization in workers postmolting. Upon ecdysis, the primary point of articulation of the mandible already initiated sclerotization, which may allow the movement of the mandibles during the shedding of the exuvium. The sclerotization of the secondary point of articulation and the mandibular teeth, and the width of sclerotization of the mandibles, progressively increased until reaching a plateau around 36-h postecdysis, which imply that workers can regain some level of activity as early as 2 d after ecdysis. Our observations allowed for the determination of variables for the sclerotization of the mouthparts to easily identify workers that recently molted, and this method will be useful in future studies that focus on the molting activity of workers over time and space within a termite colony, in the scope of improving current control strategies for termite pests.
Coptotermes travians (Haviland) is one of the most important subterranean termite pest species attacking urban buildings and structures in Malaysia. Two colonies of C. travians infesting residential premises (Colony A & B), and another one in a natural habitat (Colony C) were characterized. Foraging territories ranged between 125 - 384 m2, with maximum foraging distances of 17 - 32 m per colony. At pre-baiting, mean wood consumption were recorded at 526.4 g month-1, 478.2 g month-1 and 643.7 g month-1 for colony A, B and C, respectively. Colony sizes for the three colonies were estimated using a triple mark-recapture method. Colony size ranged between 3.2 × 105 to 1.3 × 106 workers. Baiting against colony A and B was done using both in-ground and above-ground hexaflumuron baits, while only in-ground baiting was executed against colony C. The baits caused a substantial reduction in wood consumption rate in independent monitoring stations within 34 - 44 days post-baiting. At this stage, more soldiers were observed with a small number of workers. No termite activity was visible in the independent monitoring stations, as well as the bait stations at 49, 55 and 62 days post-baiting for colony C, A and B, respectively. Some challenges of baiting subterranean termites in Malaysia are discussed.
Bistrifluron, a benzoylphenylurea compound, was evaluated for efficacy against Nasutitermes exitiosus (Hill), a mound-building species in southern Australia. Bistrifluron bait (trade name Xterm) was delivered as containerized pellets inserted into plastic feeding stations implanted in the sides of mounds—60 g for bistrifluron bait-treated mounds and 120 g of blank bait for untreated mounds. Termites actively tunneled in the gaps between pellets and removed bait from the canisters. All five treated mounds were eventually eliminated, and all five untreated mounds remained active at the end of the trial. Four of the five treated mounds were considered dead and excavated after 26 wk, but there were earlier signs of mound distress—reduced repair of experimental casement damage and reduced activity in bait canisters by 22 wk and reduced internal mound temperature after 11 wk. One treated mound showed activity in the bait station right through until almost the end of the trial (47 wk), but excavation at 49 wk showed no further activity in the mound. The five untreated colonies removed on average 97% of blank bait offered, while the five treated colonies removed on average 39.1% of bait offered. There was a wide variation in temperature profiles of mounds (up to 15 C for both minimum and maximum internal temperatures), from the beginning of the trial and even before the effects of baiting were evident.
A fluid bait, comprising α-cellulose and fine-ground phagostimulants (Summon Preferred Food Source) impregnated with 0.5% hexaflumuron (AI wt/wt) and mixed with 1% methylcel solution to yield 10% dry weight, was injected into simulated foraging galleries of Coptotermes formosanus Shiraki and Reticulitermes virginicus (Banks) for a laboratory efficacy evaluation. Six weeks after the injection, mortalities for both species exceeded 90%, and all termites died by the eight wk. The fluid bait can be applied internally through a small drill hole in a tight spot with any surface contour and may bypass many problems associated with the AG system that has to be installed externally on the walls or wood surface. When injected into an active gallery of termites in a structure, a tree, or in soil, the fluid baits may be fed immediately by termites to achieve the colony elimination.
Infestation by the eastern subterranean termite, Reticulitermes flavipes (Kollar), was found throughout the two ground floors of the pedestal of the Statue of Liberty National Monument. Termite activity in soil was also detected in two locations outside the monument walls. In total, four clusters of termite activity were identified. The widespread infestation suggested that termites had been in the monument for several years before they were noticed in 1994 and were probably introduced during the restoration project in the mid-1980s. Baits containing an insect growth regulator, hexaflumuron, were applied using above- and in-ground stations in mid-1996. By October 1997, all four infestations were eliminated after consuming a total of 1.8 g hexaflumuron. Monitoring stations remained in the soil to detect residual or new populations of subterranean termites on Liberty Island. /// [French] On a constaté l'infestation de termites souterraines, Reticulitermes flavipes (Kollar) dans les deux étages inférieurs du piédestal du Monument national de la statue de la Liberté. On a aussi décelé la présence des termites à deux autres endroits dans le sol à l'extérieur des murs du monument. Au total, quatre termitières furent localisées. L'étendue de l'infestation suggérait que les termites se trouvaient dans le bâtiment depuis plusieurs années déjà avant leur découverte en 1994, et qu'elles furent probablement introduites au cours de la restauration qui eut lieu dans les années 1980. Des appâts contenant un régulateur de croissance, l'hexaflumuron, furent placés dans le sol et en surface au cours de l'année 1996. En octobre 1997, les quatre termitières étaient éliminées, après une consommation totale de 1,8 g d'hexaflumuron. Des pièges de surveillance furent laissés en place afin de détecter d'éventuelles populations résiduelles ou une nouvelle population de termites sur Liberty Island. /// [Spanish] Se encontró una infestación de termitas subterráneas orientales, Reticulitermes flavipes (Kollar) en las dos plantas a nivel del suelo del pedestal del Monumento Nacional de la Estatua de la Libertad. También fue detectada actividad de termitas en el suelo en dos ubicaciones por fuera de las paredes del monumento. En total fueron identificados cuatro grupos de actividad de termitas. La extensión de la infestación sugirió que las termitas habían estado en el monumento por varios años antes de que fueran encontradas en 1994 y fueron introducidas probablemente durante el proyecto de restauración a mediados de la década de 1980. Se utilizaron trampas de carnada (cebo) conteniendo el regulador de crecimiento de insectos hexaflumuron, siendo ubicadas en estaciones fuera y dentro de la tierra hacia mediados de 1996. En octubre de 1997 las cuatro infestaciones fueron eliminadas después de consumir un total de 1.8-g de hexaflumuron. Las estaciones de monitoreo permanecen en la tierra para detectar poblaciones residuales o nuevas de termitas subterráneas en la Isla de la Libertad.
The efficacy of chitin synthesis inhibitors (CSIs) against fungus-growing termites is known to vary. In this study, 0.1% chlorfluazuron (CFZ) cellulose bait was tested against medium and large field colonies of Macrotermes gilvus (Hagen). The termite mounds were dissected to determine the health of the colony. Individual termites (i.e., workers and larvae) and fungus combs were subjected to gas chromatography‐mass spectrometry (GC‐MS) analysis to detect the presence of CFZ. In this study, 540.0 ± 25.8 g (or equivalent to 540.0 ± 25.8 mg active ingredient) and 680.0 ± 49.0 g (680.0 ± 49.0 mg active ingredient) of bait matrix were removed by the medium- and large-sized colonies, respectively, after baiting. All treated medium-sized colonies were moribund. The dead termites were scattered in the mound, larvae were absent, population size had decreased by 90%, and the queens appeared unhealthy. In contrast, no or limited effects were found in large-sized colonies. Only trace amounts of CFZ were detected in workers, larvae, and fungus combs, and the population of large-sized colonies had declined by only up to 40%. This might be owing to the presence of large amount of basidiomycete fungus and a drastic decrease of CFZ content per unit fungus comb (a main food source of larvae) in the large-sized colonies, and hence reduced the toxic effect and longer time is required to accumulate the lethal dose in larvae. Nevertheless, we do not deny the possibility of CSI bait eliminating or suppressing the higher termite if the test colonies could pick up adequate lethal dose by installing more bait stations and prolonging the baiting period.
The effectiveness of a chlorfluazuron termite bait in eliminating colonies of the termite species Macrotermes gilvus (Hagen) was evaluated under field conditions. Three active termite mounds were chosen for this study, two acted as test mounds and the other as the control. Four In-Ground Stations (IGS) were installed around each mound. Interception occurred almost immediately in all the stations, which were subsequently baited. The control mound was fed a bait matrix lacking the active ingredient. Stations were re-baited every 2 weeks for 10-12 weeks until bait consumption ceased in the test mounds. The mounds were left undisturbed for four more weeks before being destructively sampled. The desiccated remains of workers, soldiers, late instars and queen were found upon sampling the treated mounds. A few live termites were located in one treated mound but were darkly pigmented indicating bait consumption. The control mound remained healthy and did not show any visible sign of negative impact. The bait successfully suppressed or eliminated both M. gilvus colonies within 16 weeks from commencement of feeding.
A durable termite bait containing 0.5% noviflumuron was evaluated for physical durability, retention of active ingredient, consumption by termites, and toxicity to termites over 5 yr in field studies at locations in Indiana, Mississippi, and South Carolina. Plots in Indiana and Mississippi included both natural rainfall and irrigated plots, while plots in South Carolina received only natural rainfall. Samples collected every 3 mo for the first 4 yr were evaluated for consumption with a 7 d no-choice bioassay using Reticulitermes flavipes (Kollar). Consumption and toxicity of 5 yr samples were evaluated in similar bioassays conducted for 42 d. Durable baits received from field sites had some cracking, and a small amount of external flaking, but no major deterioration based on visual observation. There were no significant differences in noviflumuron concentration over the 5-yr period and no trend toward reduced concentrations of noviflumuron over time. Consumption of aged durable baits over 4 yr was variable, but termites usually consumed more aged durable bait than fresh durable bait and the differences were frequently significant. There were some exceptions, but termites consumed significantly more fresh durable bait than aged durable bait in only 4% of observations. When 5 yr samples were evaluated, consumption was lowest for fresh durable bait and termites consumed significantly more aged durable bait from irrigated plots in Indiana and from both natural and irrigated plots in Mississippi than fresh durable bait. Survival of termites fed blank durable bait was significantly higher than that for termites fed any of the baits containing noviflumuron and there were no significant differences in survival among the noviflumuron durable baits. Our results suggest that the bait would be durable for at least 5 yr and possibly longer under most environmental conditions.
Prior to 2001, a condominium complex in Chatsworth, California, USA, had a long history of subterranean termite activity and termite-related home owner complaints. Sentricon®stations were installed along the perimeters of 134 buildings, and inspected monthly thereafter. Sentricon® stations with actively foraging termites were immediately baited following label instructions. Two species of Reticulitermes were found at this site: R. hesperus Banks and an undescribed species of Reticulitermes (known as cuticular hydrocarbon phenotype SCA-B). When feasible, auxiliary, or additional, stations were installed adjacent to the active stations to increase the rate of station discovery and to enhance bait consumption. Within two months of installation, 41% of the buildings had Sentricon® stations with signs of subterranean termite activity. This percentage rose to 90% after 6 months and 95% after one year. Of the 7,327 Sentricon® stations initially installed, 12% had subterranean termite activity; 13% of the auxiliary stations had subterranean termite activity. Between 2002 and 2003, 70% fewer Sentricon® stations developed new termite activity, likely the result of baiting. After March 2004, very few Sentricon® stations became active. These results strongly suggest that the baiting program utilizing the Sentricon® Termite Colony Elimination System had a significant impact on both species of Reticulitermes in the subterranean termite community at this site.
effectiveness of a bait formula containing the active ingredient chlorfluazuron in controlling the subterranean termite Coptotermes curvignathus which infests houses in Jakarta. Two types of aggregation devices ('stations'), namely, in-ground stations (IGS) and above-ground stations (AGS) were applied. IGS complete with timber interceptors lining the inner station wall and a wood block in the centre was installed around the perimeter of the houses to monitor the termite activity. The number of stations installed was adjusted to the space available. Stations infested by termites were then filled with the bait matrix after the wood block was removed. The AGS (with bait matrix) were installed directly on the points of termite attack found in the houses. Stations were inspected every two weeks to determine the vigour of the termite colony based on the termite population infesting stations, ratios of soldiers:workers and the amount of bait consumption. Results showed that most bait matrix was totally consumed and the ratio of soldiers:workers initially increased and finally the termite infestation ceased. Colony elimination took about six to eight weeks after baiting. Use of the AGS was considered more practical for properties with active termites. However, a combination of treatments using the two station types is recommended.
Two chitin synthesis inhibitors, hexaflumuron and diflubenzuron, were evaluated in a laboratory choice test for their potential as bait toxicants against the Formosan subterranean termite, Coptotermes formosanus Shiraki, and the eastern subterranean termite, Reticulitermes flavipes (Kollar).Concentrations of hexaflumuron that elicited feeding deterrence were >125 ppm for C. formosanus and >62.5 ppm for R. flavipes, whereas concentrations required to cause >90% mortality at 9 wk were > 15.6 ppm and >2 ppm for C. formosanus and R. flavipes, respectively. Diflubenzuron deterred feeding of C. formosanus at such low concentrations (>2 ppm) that the highest recorded mortality was only 50% and is not likely to be effective in a bait against this termite species. More than 80% of R. flavipes workers died after feeding on diflubenzuron at >7.8 ppm, whereas feeding deterrence was recorded at >31.3 ppm. We conclude that hexaflumuron is superior to diflubenzuron as a bait toxicant because it is effective over a concentration range of 15.6-62.5 ppm. This concentration range is lethal and nondeterrent for both C. formosanus and R. flavipes. Diflubenzuron is efficacious against R. flavipes over a fairly narrow range of concentrations (7.8-31.3 ppm) and does not appear to be useful as a bait toxicant against C. formosanus.
Topical toxicity, lethal time, and bait acceptance of two slow-acting toxicants, mirex and sulfluramid, were determined for the Formosan subterranean termite, Coptotermes formosanus Shiraki, and the eastern subterranean termite, Reticulitermes flavipes (Kollar). When topically applied to C. formosanus, mirex was slightly less toxic (LD50 = 9.14 Ilg/g) than sulfluramid (LD•• = 6.95 Ilg/g). but mirex was approximately 34 times more potent (LD50 = 1.78 Ilg/ g) against R. flavipes than sulfluramid (LD50 = 60.64 Ilg/ g). Mortality of R. flavipes as a function of time was fastest for mirex and slowest for sulfluramid. Lethal time (time to kill 90% of test insects) was similar when C. formosanus was treated with either mirex or sulfluramid. Results of a choice bioassay indicated that concentration thresholds of 10 or 30 ppm in wood treated with sulfluramid were acceptable to C. formosanus and R. flavipes, respectively. These treatments also produced significant mortality (˜68% mortality at ˜4 ppm for C.formosanus, ˜80% mortality at ˜18 ppm for R. flavipes) after an 8-wk exposure. Wood blocks treated with ˜90 ppm mirex were accepted by C. formosanus. Mirex concentrations of ˜10 ppm produced ˜68% mortality. R. flavipes accepted blocks treated with up to 15 ppm of mirex and were killed at significantly higher rates (˜80%) when exposed to blocks treated with ˜9 ppm of mirex.
Commercial prototype monitoring/baiting stations were used to detect, bait, and elminate field populations of the Formosan subterranean termite, Coptotermes fornwsanus Shiraki, and the eastern subterranean termite, Reticulitermes flavipes (Kollar), near structures. Because of the durable plastic housing, the station can be used by pest control professionals for ongoing monitoring and baiting programs to provide continuous protection of structures from subterranean termites.
Above-ground bait stations composed of reclosable plastic bags containing bait matrices impregnated with hexaflumuron were placed directly over active infestations of the Formosan subterranean termite, Coptotermes formosanus Shiraki. Of the 5 colonies tested, 2 each of aerial colonies and ground-based colonies were eliminated. The population of 1 ground-based colony was reduced from >2,000,000 to 155,000 foragers. The results demonstrated the feasibility of introducing baits into active areas of infestation of subterranean termites. In addition to the in-ground baiting system, the above-ground bait station may offer another option for bait delivery to affect the structure-infesting populations of subterranean termites.
Wooden boards impregnated with sulfluramid were nailed together with boards treated with acetone to form a block for placement in selected monitoring stations of 3 colonies of the Formosan subterranean termite, Coptotermes fomwsanus Shiraki, in Hallandale, FL. Under this choice-test condition, sulfluramid-treated boards initially accepted by termites were later avoided. When sulfluramid concentration was reduced, differences in feeding between sulfluramid-treated boards and boards treated with acetone only became insignificant, indicating non preferential feeding by the same population at the reduced toxicant concentration. Feeding deterrence was detected even for the reduced toxicant boards in later months for SOI1lP colonies. We hypothesized an associative learning by C. formosanus to avoid feeding on The treatments. The 12-mo baiting with sulfluramid-treated blocks reduces foraging populations of the treated colonies by 52-86%. Without additional baiting, all populations substantially recovered in later years. It is suggested that lethal time (time required to kill) of a bait toxicant must be dose independent to be delivered to the majority of the population using a feeding medium.
An areawide project was carried out in a low-income community of Cerro Navia in Santiago, Chile, to manage the population of the invasive Reticulitermes flavipes (Kollar) that has been causing severe damage to homes in the past 20 yr. With the help of the municipality government and residents, baits containing the chitin synthesis inhibitor hexaflumuron were applied in three town blocks of a six-block area in January 2001. By April 2002, most of the termite activity in the baited town block was eliminated. A Bait Impact Index demonstrated that more baits applied near a monitoring station significantly reduced R. flavipes activity in the station. Following the successful reduction of termite activity in the three baited blocks, hexaflumuron baits were applied in the entire six-block area in 2003-2004. Since May 2005, R. flavipes has not been detected in the test area. The areawide approach significantly reduced the cost of bait application for managing the R. flavipes populations in the community. The project serves as a model of adapting an advanced but often costly technology for use in developing counties that otherwise would not be able to afford it.
A baiting procedure that incorporated a matrix containing a chitin synthesis inhibitor, hexaflumuron, was evaluated against field colonies of the eastern subterranean termite, Reticulitermes flavipes (Kollar), and the Formosan subterranean termite, Coptotermes formosanus Shiraki. Wooden stakes were first driven into the soil to detect the presence of termites. Bait tubes were placed in soil where termites were detected. A self-recruiting procedure, in which termites collected from wooden stakes were forced to tunnel through the matrix in the bait tubes, significantly increased bait intake by termites. Approximately 4-1,500 mg of hexaflumuron was needed for 90-100% reduction of field populations containing 0.17-2.8 million foragers per colony.
A-9248 (diiodomethyl para-tolyl sulfone) baits treated at 600 ppm (wt/wt) were introduced into selected trap stations of three colonies of the Formosan subterranean termite, Coptotermes formosanus Shiraki, in Hallandale, Fla., between November 1987 and November 1988. Termites did not avoid foraging at sites containing treatment and nor was feeding significantly reduced on the treated versus untreated baits. One year after bait application, foraging populations of three colonies that received A-9248baits were reduced 65-98%. The results demonstrated that a toxicant bait can be used to suppress foraging populations of subterranean termite colonies and hence reduce their damage potential.
The topical LD50 of A-9248 (diiodomethyl para-tolyl sulfone) against the Formosan subterranean termite, Coptotermes formosanus Shiraki, was estimated at 141.7 µg/g with 95% fiducial limits of 1l0.4-168.3 µg/g. A-9248 showed protracted activity against this termite. Time required to kill 90% of C. formosanus (ELT90) was 8.4-18.9 d when administered topically, 21-26 dafter 24-h forced feeding, and 19-22 d when C. formosan us were confined continuously on treated feeding substrate. Results of a choice test revealed that A-9248 is a feeding deterrent at concentrations ≥8,000 ppm. Initially, C. formosanus fed on wood treated with 1,000-6,000 ppm A-9248 but learned to avoid the treatment as a result of ingesting sublethal doses of A-9248. Only those groups exposed to wood treated with <1,000 ppm continued feeding on the treated substrate; ingestion of these concentrations resulted in 85-100% mortality at the end of the 4-wk experiment.
Laboratory techniques developed to evaluate insecticides for prevention or remedial control of infestations of Coptotermes formosanus Shiraki showed that the evaluation could not be based on mortality alone. The behavioral responses of the termites to the insecticides had to be considered. The termites can seal off or avoid treated areas and effectively protect themselves. Factors causing this behavior appear to be the repellency of the insecticide itself or chemical factor(s) associated with dead termites. The insecticides tested could be divided into three groups, depending on the reactions of the termites. Types I and II can be used in preventative treatments. Only type III can be used in remedial treatments.
Four buildings (two high-rise condominiums, a single-family residential structure, and a trailer) in Broward and Miami-Dade Counties, Florida, infested with Formosan subterranean termites (FST, Coptotermes fomosanus Shiraki) were treated with baits containing 0.5% wt/wt noviflumuron. Each building represented a challenging treatment scenario for liquid termiticides due to the location of the infestation within the structure and/or occupant refusal to permit pesticide application in termite-infested living and activity areas. Marking of FST by in-situ baiting with blank bait matrix treated with 0.5% wt/wt Neutral Red dye indicated only one FST foraging population infested each building. Two FST infestations were aerial in high-rise condominiums. Noviflumuron baits were applied to two buildings in aboveground stations, one building with in-ground stations, and the remaining building with both station types. All detected FST infestations were eliminated within 71-92 days after first application of noviflumuron baits. FST foraging populations with confirmed ground contact consumed approximately 4-fold more bait than did aerial infestations; mean ± SD, 242 ± 74 g vs. 62 ± 51 g, respectively. Termite feeding activity was monitored before, during, and after bait application at two buildings with an acoustic emissions detector (AED) and in one building with a microwave detector. Cessation of termite activity measured with these devices corresponded with elimination of live FST previously observed in stations, infested wood, and foraging tubes. No FST were observed in any monitoring station or building during the 12-18 month inspection period following elimination of the detected FST infestation.
Soil insecticide barriers have been the single most important tool for subterranean termite control in the last half century, but limitations with current soil termiticides have provided the impetus to look for alternatives in recent years. One such alternative is the monitoring--baiting programme. Monitoring stations to detect termites are placed in the soil surrounding a structure. Once termites are found in the stations, monitoring devices are replaced with slow-acting baits such as the chitin synthesis inhibitor, hexaflumuron. Field studies have indicated that termite colonies were eliminated using less than 1 g of hexaflumuron. After the elimination, monitoring resumes and bait is applied if new termite activity is detected. The monitoring and baiting procedure form the basis for an ongoing programme to protect structures from subterranean termite infestation. Although the cost--benefit model developed for agricultural integrated pest management cannot be applied directly to termite control, the underlying concept for using a cost-effective approach remains the same. The benefits of the monitoring--baiting programme over conventional soil treatment are a reduction in pesticide applied per unit and the elimination of termite populations near structures, resulting in the reduction of liability and damage potential. It is expected that the data management system when used in conjunction with the monitoring--baiting programme will provide a database to improve its cost-effectiveness continuously.
Using a quarterly (3-mo) monitoring and bait-replenishment interval, 122 subterranean termite colonies throughout the United States were baited with a refined cellulose bait matrix containing 0.5% noviflumuron. All colonies were eliminated in less than 1 yr after initiation of baiting as determined by long-term monitoring and genetic markers. Sixty-three percent of the colonies were eliminated during the first quarter after the initiation of baiting and 77% of colonies were eliminated after consuming two bait tubes or less. This suggests that a single baiting cycle and bait installed in response to a single active monitoring device were sufficient to eliminate the majority of colonies. Although termites temporarily abandoned stations after depleting bait, workers resumed feeding when baits were replenished. Colonies that consumed large amounts of bait before elimination foraged into multiple stations, thus allowing adequate amounts of bait to sustain feeding. The time to eliminate termite colonies with bait replenished quarterly was similar to that previously reported for laminated cellulose bait replenished monthly. Our data support the conclusion that extending the bait replenishment interval from monthly to quarterly for bait tubes with refined cellulose containing 0.5% noviflumuron did not adversely impact colony elimination.
Periodic sampling of 43 independent monitors, initially active with Formosan subterranean termite, Coptotermes formosanus Shiraki, or the eastern subterranean termite, Reticulitermes flavipes (Kollar) (Isoptera: Rhinotermitidae), was conducted to evaluate the effects of cellulose baits containing one of three chitin synthesis inhibitors (CSIs)-diflubenzuron, hexaflumuron, or chlorfluazuron-on termite populations. Diflubenzuron at 0.1% active ingredient (AI, wt:wt) had no noticeable effect on termite populations. Chlorfluazuron (0.25% [AI]) significantly reduced termite populations in approximately 3 yr. Chlorfluazuron used after > 2-yr diflubenzuron treatment significantly reduced termite populations within months. This suggests diflubenzuron exposure increased the termite's sensitivity to chlorfluazuron accelerating population collapse. Hexaflumuron (0.5% [AI]) also reduced termite populations in approximately 2 yr. The process of removing most detectable termite populations from the approximately 160,000-m2 campus of the Southern Regional Research Center, New Orleans, LA, with CSIs baits required approximately 3 yr. Adjustments in the specific bait formulations and application procedures might reduce time to suppression. Establishment of new independent termite populations provides a mechanism to minimize the effects of baits. Remedial control measures around and under structures should be considered when implementing an area wide management strategy.
The efficacy of Xterm, which contains 1% bistrifluron, in the form of cellulose bait pellets was evaluated for its efficacy in eradicating field colonies of the mound-building termite Globitermes sulphureus (Haviland) (Isoptera: Termitidae). The termite mounds were dissected at the end of the experiment to determine whether the colonies were eliminated. By approximately 2 mo postbaiting, the body of termite workers appeared marble white, and mites were present on the body. The soldier-worker ratio increased drastically in the colonies, and the wall surface of the mounds started to erode. Colony elimination required at least a 4-mo baiting period. Mound dissection revealed wet carton materials (food store) that were greatly consumed and overgrown by fast-growing fungi. Decaying cadavers were scattered all over the nests. On average, 84.1 +/- 16.4 g of bait matrix (68.9 +/- 13.4%, an equivalent of 841 +/- 164 mg of bistrifluron) was consumed in each colony. Moreover, we found that a mere 143 mg of bistrifluron was sufficient to eliminate a colony of C. sulphureus.
The efficacy of bistrifluron, a chitin synthesis inhibitor, in cellulose bait pellets was evaluated on the mound-building subterranean termite, Coptotermes acinaciformis (Froggatt). Three concentrations of the bistrifluron were used: 0 (untreated control), 0.5, and 1.0% over an 8 wk period. Both doses of bistrifluron bait eliminated (viz. termites absent from nest or mound) termite colonies: 83% of colonies (10 of 12) were either eliminated or moribund (viz. colony had no reproductive capacity and decreased workforce) after 8 wk, compared with none of the control colonies. The remaining two treated colonies were deemed to be in decline. Early signs that bistrifluron was affecting the colonies included: 3 wk after baiting mound temperatures showed a loss of metabolic heat, 4 wk after baiting foraging activity in feeding stations was reduced or absent, and dissection of two mounds at 4 wk showed they were moribund. Colony elimination was achieved in around half or less the time, and with less bait toxicant, than other bait products tested under similar conditions in the field, because of either the active ingredient, the high surface area of the pellets, or a combination of both. This suggests the sometimes long times reported for control using baits may be reduced significantly. The use of a mound building species demonstrated clearly colony level effects before and after termites stopped foraging in bait stations.
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.
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.
The development of baits for subterranean termite control over the past 25 yr has provided cost-effective alternatives to liquid termiticide treatments. Current bait products use one of the few available benzoylurea chitin synthesis inhibitors (CSIs) labeled for subterranean termites. These insecticides are used because of their nonrepellency, their slow-acting mode of action, and their dose-independent lethal time. Although many studies have provided ample evidence of the efficacy of CSI baits for subterranean termite colony elimination, most have focused on hexaflumuron and noviflumuron. However, bait products using alternative CSIs have not received the same level of scrutiny, limiting the amount of evidence proving their efficacy. One such compound is novaluron, the active ingredient currently used in the Trelona ATBS-Advance Termite Baiting System bait product. The current study independently tested the efficacy of this commercially available bait formulation against whole colonies of Coptotermes gestroi (Wamann) (~63,910 workers) in the laboratory, using an extended experimental setup to simulate a 15-m foraging distance from the central part of the nest to the bait, while having access to alternative food sources. Treated colonies progressively ceased to feed on wood items within 45 d after being provided access to the novaluron bait formulation, with a subsequent progressive collapse of the population, leading to colony elimination by 91 d. This study therefore confirms the efficacy of novaluron baits against subterranean termites, and currently remains one of the few CSIs that can be applied for the successful control of Coptotermes infestations.
Fluid baits comprised of 10% dry medium (impregnated with 0.5% hexaflumuron) and 90% methylcel solution were injected into foraging galleries of the Formosan subterranean termite, Coptotermes formosanus Shiraki (Blattodea: Rhinotermitidae), in trees and buildings. Elimination times at two of the six baited sites were longer than expected, possibly due to the application disturbance or the presence of an old and declining colony, but fluid bait treatments eliminated all baited colonies. Fluid baits were injected through drill holes behind infested wood surface, and bypassed the difficulties for installing above-ground (AG) bait stations on uneven surface or at tight corners. Because a large quantity of fluid baits could be applied at once, termite control professionals may be able to avoid revisiting the site to add more baits. The absence of unsightly AG station in a house will also make fluid baits more acceptable to homeowners than AG baits. Currently, local applications of liquid termiticides are common practices because termite control professionals are often urged by homeowners to take remedial actions when termites are found in a house, but such treatments only drive termites away from the active loci without affecting the termite colony(s). Remedial treatments with fluid baits would result in immediate bait consumption and shorten colony elimination time with or without the use of in-ground baiting systems. Introduction of fluid baits will add another tool to the termite control industry and will make it more plausible for the homeowners to accept baiting technology.
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.
Baiting systems have been introduced using slow-acting bait toxicants to provide environment-friendly and target-specific termite management. In the present study, the Exterra termite bait system (USA) with chlorfluazuron, a chitin synthesis inhibitor, as the active ingredient was tested against termite colonies. Ten residential areas of Lahore, infested with subterranean termites were selected for the study. The study period was from 2013 to 2015. In-ground stations were installed at 10 sites and above-ground stations were only installed at four test sites. Requiem termite bait was prepared according to the label instructions. Results showed that the range of termite activity was between 30 and 214 d to first termite activity on underground monitors with a mean of 78.23 ± 6.44. Timeline graphs also show activity of termites and active ingredient placement for each of the stations at each site. As termite feeding activity in the stations increased, there was a decrease in termite activities in wooden structures, followed by cessation of termite feeding and foraging activity noted in the building structures. It was concluded that a termite baiting system in Pakistan has the potential to suppress and reduce termite populations, when foraging termites feed on the active ingredient and share with nest mates through trophallaxis by installing more bait stations and prolonging baiting period.
A field study was initiated in 2009 with 0.5% novaluron the BASF Advance Termite Bait System, which was 100% effective in controlling Reticulitermes sp. Holmgren and Coptotermes formosanus Shiraki infestations on 11 structures in the Texas City, TX area. Stations with inspection cartridges (cellulose tablets) and monitoring bases (southern yellow pine) and independent monitoring devices were installed in an alternating pattern around each structure and were inspected every 30 d postinstallation. When subterranean termite activity was confirmed on the inspection cartridge or the monitoring base, the inspection cartridge was removed and replaced with a bait cartridge containing 0.5% novaluron insecticide on a proprietary matrix (124 g/cartridge) in a station. Once the novaluron-treated bait was inserted, inspections of that station were made on a 4-mo cycle until no termite activity was observed. The mean time to achieve control of the subterranean termites on the structures was 10.5 mo post initial installation of bait. Mean time to achieve control of the termites on the structures after the baits were installed was 5.4 mo. Control of the termites on the structures required consumption of a mean of 1.3 bait cartridges (166.2 g) of 0.5% novaluron bait matrix per structure. These results indicate that the baits with 0.5% novaluron were effective in controlling termites on the structures used in this study.
A field trial with toxic-bait blocks for suppression of subterranean termite activity was initiated in Toronto. Decayed, mirex-impregnated red pine wood blocks 2.5 × 3.8 × 0.5 cm were placed individually in soil at 1.5-m intervals. Attack on bait blocks effectively suppressed termite activity for 3 years in the eight plots. The method offers a cheaper, environmentally sound, effective alternative to conventional soil-poisoning methods.
A cooperative project between Forest Products Laboratories in the United States and Canada, initiated in 1966 to study the control effectiveness of an insecticide-treated termite attractant, is reported. It represents a bait method of control being developed to eradicate relatively large pockets of infestation.
Wooden bait blocks decayed by Lenzites trabea (Pers.) Fr., which attracts termites, with and without poison coating (Mirex insecticide) were installed in experimental plots at Oxley, Ont. An abrupt suppression of termite foraging occurred in plots where insecticide was used. Observations will be continued and work extended to determine whether the poison will prevent subterranean expansion of colonies and to assess its degree of effectiveness in eliminating localized pockets of infestation.
A field trial was conducted in southern Mississippi to determine if placing decayed wood bait blocks impregnated with mirex could suppress termite (Reticulitermes sp.) populations when placed around the perimeter of an area. Bait blocks treated with 10 mg mirex/block were buried at 1.5-m spacing at the perimeter of six 7.5 m-square plots, 3 of which also had treatment along the perimeter of an outer 30-m square. Noninsecticidal bait blocks were used to monitor termite activity within the treatment lines. During a 3.5-yr period, termite activity on the treated plots was suppressed. The efficacy of mirex bait treatment for the protection of man-made structures is disscussed.
A field trial with mirex as bait for Reticulitermes spp. was initiated in S Mississippi. Sound wood and attractant (decayed) wood-bait blocks, O.6×2.5×3.8 cm, pressure impregnated with mirex solution to a retention of 32 mg/block, were placed individually in the soil at 1.5-m spacing. Termite attacks on southern pine reference stakes were suppressed effectively. Since the termites fed more heavily on decayed than on sound wood, pickup of insecticides by the termites was far greater from the attractant blocks. An original installation of the mirex-attractant blocks effectively suppressed termites for 3 years.
Two aspects of the Exterra Termite Interception and Baiting System (Ensystex, Fayetteville, NC) were evaluated in a field experiment using 13 termite mounds near Townsville, Australia. First, a cellulose-acetate powder containing either 0.05% wt:wt or 0.25% wt:wt chlorfluazuron (Requiem, Ensystex, Fayetteville, NC) was tested for its efficacy in eliminating colonies of the xylophagous mound-building subterranean termite Coptotermes acinaciformis (Froggatt). The moist bait matrix was replenished during the first inspection of 10 mounds (five mounds by two treatments) used in the experiment. Second, a single application of the moist bait matrix was used on three additional mounds to test termite responses and the effectiveness of 0.25% wt:wt chlorfluazuron. Although there was no evidence of repellence, there was little removal of replenished bait. Five colonies were eliminated by 0.05% wt:wt chlorfluazuron and five colonies by 0.25% wt:wt chlorfluazuron: another colony was moribund, and elimination appeared imminent. Colony decline was first suspected some 12 wk after bait application, and colony elimination was confirmed, by destructive sampling, about 5 wk later. Colony elimination may have occurred within 12 wk. One colony was an anomaly and did not succumb to the effects of the toxicant. Another colony was not eliminated because of invasion of the baiting system by ants. Ants, principally Iridomyrmex purpureus (F. Smith) group and Papyrius nitidus (Mayr) group, occurred commonly in the stations during the experiment. Microcerotermes sp. was found in five of the C. acinaciformis mounds, after colony elimination. Inspections of small sections of mounds and wooden dowels inserted into mounds were reliable methods for monitoring colony health.
Laboratory performance and pharmacokinetics of the benzoylphenylurea noviflumuron in eastern subterranean termites (Isoptera: Rhinotermitidae)
- Karr