Field evaluation of the bait toxicant chlorfluazuron in eliminating Coptotermes acinaciformis (Froggatt) (Isoptera: Rhinotermitidae)

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.     

Elimination of subterranean termite (Isoptera: Rhinotermitidae) colonies using a refined cellulose bait matrix containing noviflumuron when monitored and replenished quarterly

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.     

Evaluation of hexaflumuron for controlling the subterranean termite Coptotermes curvignathus (Isoptera: Rhinotermitidae) in Malaysia

Cellulosic bait matrices containing 0.5% hexaflumuron were tested against field colonies of the subterranean termite Coptotermes curvignathus Holmgren in Malaysia. Foraging activities of the termites were first monitored for several months by using survey stakes and wood bundles placed in underground monitoring traps. Infested stakes were replaced with bait devices. Termite workers to act as recruits were collected from infested stakes and placed in the bait devices. Subsequent activities of the termites were monitored by examining and weighing the wood in the monitoring traps. Data show that the four colonies had populations of 166,288-709,052 foragers and mean wood consumption rates of 305.9-508.2 g/mo per trap. These colonies ceased their activities at all monitoring devices 25-44 d after baiting had commenced. Colonies consumed approximately 27-79 g of bait matrix or 137.5-395 mg of hexaflumuron. Thus, C. curvignathus colonies could be monitored, characterized, baited, and foraging eliminated by using a bait matrix containing hexaflumuron.     

Field evaluation of a fipronil bait against subterranean termite Odontotermes formosanus (Isoptera: Termitidae)

The subterranean termite Odontotermes formosanus Shiraki is an important pest of agronomic crops, plantations, and forestry, and it endangers earthen dikes and dams in China. A fipronil bait consisting of straw pulp and white sugar was evaluated against field colonies of O. formosanus. Triple mark-capture with Nile blue dye was used to delineate foraging territories and to estimate foraging populations of four O. formosanus colonies locating in the campus of Huazhong Agricultural University, Wuhan, China. Termite activity was monitored by number of termite workers and straw board consumption in underground monitoring stations. Consumption of bait matrix and fipronil was estimated for each testing site. The results showed that approximately 3-5 mg of fipronil could suppress foraging populations of O. formosanus containing 0.4-0.7 million foragers per colony. Baits containing fipronil seem to be a feasible alternative for controlling O. formosanus.     

Laboratory evaluation of bistrifluron, a benzoylphenylurea compound, as a bait toxicant against Coptotermes formosanus (Isoptera: Rhinotermitidae)

Bistrifluron, a benzoylphenylurea compound, was evaluated with regard to its efficacy against workers of Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae) by using three laboratory tests. In the no-choice feeding test, the mortality of bistrifluron-treated worker termites was significantly higher than that of termites exposed to the same concentrations of hexaflumuron (e.g., 6 wk at 500 ppm, 4 wk at 5,000 ppm, and 2 wk at 50,000 ppm) and untreated controls. Bistrifluron showed higher dose dependence and a faster speed of action than hexaflumuron. Both bistrifluron and hexaflumuron had feeding-deterrent effects at 5,000 ppm in the two-choice feeding test, although the mortality of worker termites exposed to bistrifluron or hexaflumuron at 5,000 ppm was not significantly different from untreated controls. In the allogrooming inhibition test, to examine effects of bistrifluron on allogrooming behavior of termites, termite movement was affected at 1 wk before termites died when exposed to 5,000 ppm bistrifluron. These results indicate bistrifluron is effective as a bait toxicant at 5,000 ppm; however, bistrifluron may cause some feeding repellency at > or = 5,000 ppm.     

Ant and termite mound coinhabitants in the wetlands of Santo Antonio da Patrulha, Rio Grande do Sul, Brazil.

This paper reports on ant and termite species inhabiting the mounds (murundus) found in three wetland sites in Santo Antonio da Patrulha. Ants and termites were found in 100% of the mounds of two sites and in 20% of those in the third site. Colonies of Camponotus fastigatus were found inhabiting all the mounds, while colonies of Brachymyrmex sp., Linepithema sp., Pheidole sp., and/or Solenopsis sp. were collected in less than 30% of the mounds. In the mounds of the three sites, colonies of Anoplotermes sp. and/or Aparatermes sp. termites were found together with the ant colonies. Another cohabiting termite species, Cortaritermes sp., was found only in the mounds of one site. The results suggest that C. fastigatus is the species building the mounds, with the other species, whether ants or termites, being the inquilines.     

Termite cohabitation: the relative effect of biotic and abiotic factors on mound biodiversity

1. Termites are important ecosystem engineers that improve primary productivity in trees and animal diversity outside their mounds. However, their ecological relationship with the species nesting inside their mounds is poorly understood. 2. The presence of termite cohabitant colonies inside 145 Cornitermes cumulans mounds of known size and location was recorded. Using network‐theoretical methods in conjunction with a suite of statistical analyses, the relative influence of biotic and abiotic drivers of termite within‐mound diversity on the composition and species richness of the termite community was investigated, specifically builder presence and physical aspects of the mound. 3. We found that richness inside the mound increases with mound size, and the species similarity between mounds decreases with distance. The physical attributes (abiotic drivers) of termite mounds (size and relative distance to other mounds) are the strongest predictors of termite species richness and composition. The biotic driver (presence of a builder colony) has an important, though smaller, negative effect on within‐mound termite species richness. 4. The findings suggest that the termites' physical manipulation of their environment is an important driver of within‐mound community diversity. More generally, the approach taken here, using a combination of statistical and network‐theoretical methods, can be used to determine the relative importance of abiotic and biotic drivers of diversity in a wide range of communities of interacting species.     

Intra- and interspecific agonistic behavior of the subterranean termite Microcerotermes crassus (Isoptera: Termitidae)

The aim of our study was to investigate the intra- and interspecific agonistic behaviors exhibited by the worker and soldier castes of the subterranean termite Microcerotermes crassus Snyder (Isoptera: Termitidae). Aggression between M. crassus colonies from different field locations and also against three termite species--Coptotermes gestroi (Wasmann), Globitermnes sulphureus Haviland, and Odontotermes sp.--were observed in the laboratory. Termite responses were tested in paired combination of castes (soldiers versus soldiers, soldiers versus workers, and workers versus workers) consisting of 10 individuals each. Significant agonistic behaviors were observed only in encounters between pairings of different termite species. M. crassus was aggressive toward individuals from different species but not toward individuals from different M. crassus colonies. Mortality of M. crassus reached 100% in most of the interspecific encounters. However, no or low mortality was recorded in the intraspecific pairings.     

Response of Reticulitermes spp. (Isoptera: Rhinotermitidae) in northern California to baiting with hexaflumuron with sentricon termite colony elimination system

Colonies of Reticulitermes spp. were baited with prototype and commercial Sentricon stations (Dow AgroSciences LLC, Indianapolis, IN) to test the efficacy of hexaflumuron in different concentrations and bait matrices and to document reinvasion of the foraging territories vacated by eliminated colonies. Seven colonies of Reticuliternes spp. from two sites were characterized with cuticular hydrocarbon analyses and mark-release-recapture and agonistic behavioral studies. Three colonies were observed as controls and four colonies were baited. When a connection between the bait station and the monitoring station could not be confirmed by mark-release-recapture studies, the results of the baiting were equivocal. The monitoring stations of a colony at our wildland site were devoid of termites 406 d after baiting with one Sentricon station, but became reoccupied with the same species of termites approximately 6 mo after baiting. A colony at the residential site was baited with 0.5% hexaflumuron in the Recurit II bait matrix; 60 d later termites were absent from all monitoring stations. These monitoring stations remained unoccupied for > or = 18 mo. Foraging Reticulitermes spp. appeared in three of the seven monitoring stations 18, 24, and 36 mo after baiting, respectively. Using cuticular hydrocarbon analyses and agonistic behavior studies, we determined that the Reticulitermes spp. occupying these monitoring stations were from three different colonies; none were members of the original colony destroyed by baiting. Another colony at the residential site was baited using a noncommercial, experimental bait; 52 d later termites were absent from all monitoring stations. The monitoring stations remained unoccupied for > or = 9 mo. A different Reticulitermes sp. colony invaded one monitoring station 9 mo after baiting.     

Colony social organization and population genetic structure of an introduced population of formosan subterranean termite from New Orleans, Louisiana

The Formosan subterranean termite, Coptotermes formosanus Shiraki, is an invasive species in many parts of the world, including the U.S. mainland. The reasons for its invasive success may have to do with the flexible social and spatial organization of colonies. We investigated the population and breeding structure of 14 C. formosanus colonies in Louis Armstrong Park, New Orleans, LA. This population has been the focus of extensive study for many years, providing the opportunity to relate aspects of colony breeding structure to previous findings on colony characteristics such as body weight and number of workers, wood consumption, and intercolony aggression. Eight colonies were headed by a single pair of outbred reproductives (simple families), whereas six colonies were headed by low numbers of multiple kings and/or queens that were likely the neotenic descendants of the original colony (extended families). Within the foraging area of one large extended family colony, we found genetic differentiation among different collection sites, suggesting the presence of separate reproductive centers. No significant difference between simple family colonies and extended family colonies was found in worker body weight, soldier body weight, foraging area, population size, or wood consumption. However, level of inbreeding within colonies was negatively correlated with worker body weight and positively correlated with wood consumption. Also, genetic distance between colonies was positively correlated with aggression levels, suggesting a genetic basis to nestmate discrimination cues in this termite population. No obvious trait associated with colony reproductive structure was found that could account for the invasion success of this species.     

Foraging population and territory estimates for Microcerotermes diversus (Isoptera: Termitidae) through mark-release-recapture in Ahwaz (Khouzestan, Iran)

Microcerotermes diversus Silvestri (Isoptera: Termitidae), an important pest in Ahwaz (Khouzestan, Iran), causes serious economic damage to wooden products in buildings. In this study, we determined the foraging populations and territories of this species using mark-release-recapture techniques. Based on both the weighted mean model and Lincoln index methods, mean termite foraging population estimates for two colonies, A and B, were 2,984,489 +/- 258,802 and 326,134 +/- 8,713, respectively. Estimates with the Lincoln index were 2,731,229 +/- 813,081 for colony A and 321,493 +/- 138,499 for colony B. Estimated horizontal foraging territories for colonies A and B were 25.59 and 44.16 m2, respectively. The maximum and minimum linear foraging distances were 5.40 and 2.14 m for colony A and 9.14 and 1.86 m for colony B, respectively. Our data expand the knowledge about the biology, ecology and behavior of M. diversus.     

Population density, species abundance, and breeding structure of subterranean termite colonies in and around infested houses in central North Carolina

Pressure from subterranean termites is known to vary geographically across the United States, but there are few quantitative studies concerning the threat of structural infestation for any geographic region. We assessed the number and locations of termite colonies present on 20 infested residential properties in central North Carolina, where subterranean termite pressure is considered to be heavy. This was achieved by using microsatellite markers to determine colony identity of termites collected over 6-14 mo from mud tubes in structures, below-ground monitors, and wood debris in the yard. In total, we identified 188 distinct colonies and determined their breeding structures. Reticulitermes flavipes (Kollar) was by far the most common species, accounting for nearly 90% of all colonies; the remaining colonies belonged to Reticulitermes hageni Banks and Reticulitermes virginicus (Banks). In four cases, there were two colonies infesting a structure simultaneously; in all other cases only a single colony was detected in the structure. Colony densities were high, averaging 62 colonies per ha (25 per acre) with a maximum of 185 colonies per ha (75 colonies per acre). Foraging ranges of R. flavipes and R. hageni colonies were generally small (<30 linear m), and most colonies were headed by a single pair of monogamous reproductives with nearly all the remaining colonies headed by relatively few inbreeding descendants of the original monogamous pair. These results provide the most detailed picture to date of the number, distribution, and colony characteristics of subterranean termite colonies located in and around residential structures.     

Population structure and colony composition of two Zootermopsis nevadensis subspecies

Understanding the origin and maintenance of eusociality in termites has proved problematic, in part, due to a lack of knowledge concerning the variability and evolutionary changes in termite breeding structure. One way to address this is to compare the population genetics of a broad range of termite species. However, few studies have investigated the population genetics of basal termite taxa. We used 12 polymorphic microsatellite loci to characterize and compare the colony genetic structure of 18 colonies of two basal termite subspecies, Zootermopsis nevadensis nevadensis and Zootermopsis nevadensis nuttingi. The average relatedness (r) among individuals within a colony was high (0.59) and similar to values reported for other termite species. Average relatedness between colony founders was lower (0.21) suggesting the alates outbreed. Genotypes of workers and soldiers in 4 out of the 18 colonies were consistent with reproduction by a single pair of primary reproductives and the remaining colonies were inferred to have been derived from more than two reproductives. Eleven colonies with three or more reproductives were consistent with replacement reproductives (neotenics) and the remaining three colonies included genetic contribution from three or more primary reproductives. Comparisons between the subspecies revealed significant differences in breeding structure, specifically in the number and types of reproductives (that is, primaries or neotenics). Furthermore, we observed a larger proportion of colonies with greater than three primary reproductives compared to more derived termite lineages. Thus, our results suggest that breeding structure can vary significantly among termite taxa.     

Mutualistic acacia ants exhibit reduced aggression and more frequent off‐tree movements near termite mounds

In many ant–plant mutualisms, ants establish colonies in hollow thorns, leaf pouches, or other specialized structures on their host plants, which they then defend from herbivores. Resource heterogeneity could affect the maintenance of these mutualisms if it leads to one or both partners altering their investment in the interaction. Such a phenomenon may be especially pertinent to the Acacia–ant mutualism found in East African savannas, where termite mounds have a profound effect on the spatial structuring of resources used by both plants and ants. Here, we examined whether the proximity to termite mounds of Acacia drepanolobium trees is associated with variation in the behavior of one of their ant associates, Crematogaster nigriceps. We found that ant colonies near termite mounds had decreased aggressive responses to simulated herbivory as well as increased off‐tree movement. We hypothesize that these changes are the result of resident ant colonies near termite mounds shifting investment from defense of their host plant to foraging for nearby resources.     

The distribution,abundance, and the effects of fire on mound building termites (Trinervitermes and Cubitermes spp., Isoptera: Termitidae) in northern guinea savanna West Africa

Summary Termite mound densities in typical guinea savanna, Detarium, and grassland (boval) habitats in northern guinea savanna were determined by random quadratting of 2–3 sites in each habitat (100, 10x10 m quadrats per habitat). Dominant species in guinea savanna were T. geminatus (46 mounds ha^-1) and T. oeconomus (21 mounds ha^-1), in Detarium T. geminatus (59 mounds ha^-1) and C. curtatus (45 mounds ha^-1) and in boval C. curtatus (72 mounds ha^-1) and T. geminatus (22 mounds ha^-1). Only C. curtatus densities and total densities differed significantly between sites within habitats, but all species differed significantly in abundance between habitats. The composition of each community was related to general environment but no particular environmental variable was shown to be a major determinant of termite distribution. Evidence for the limitation of termite populations was obtained from indirect evidence of competition between colonies in Detarium, and by experimental manipulation of fire regimes in the typical guinea savanna habitat. Harvester termites increased four-five fold over two years in fire-protected plots as a result of increased food supplies. Total termite densities in the fire-protected community equilibrated to the new population density (100 mounds ha^-1) after only two-three years.     

Multi-scale pattern analysis of a mound-building termite species

Termite mounds are a widespread feature in most African savannas. These structures exhibit high nutrient contents and often host a special vegetation composition. In this study, we analysed mound distribution patterns of a fungus-growing termite species, Macrotermes michaelseni, an important ecosystem engineer in the savannas of Namibia. Inhabited mounds taller than 0.7 m were regularly distributed. We view this pattern as a result of intraspecific competition. The heights of mounds taller than 0.7 m were correlated positively with their distance, such that mounds closer together, i.e. up to inter-mound distances of approximately 50 m, tended to be smaller than average. This indicates that intraspecific competition for foraging areas controls mound distribution pattern and colony size. Differences between mound heights increased on the spatial scale up to inter-mound distances of 80 m. We assume that the foundation of new colonies is only possible in unoccupied patches. In such patches, young colonies are able to occur close together as they have a relatively low foraging demand and therefore a low spatial demand. In contrast, their critical distance to taller colonies with higher foraging demands is rather large, which leads to the observed increasing difference of mound heights with increasing distances between them.     

蚁丘被破坏程度对红火蚁蚁群迁移的影响

本文调查研究了蚁丘被破坏的程度对红火蚁Solenopsis invicta Buren蚁群迁移的影响。结果表明,蚁巢地表部分被破坏可导致红火蚁蚁群发生分巢、搬巢等现象,蚁群的移巢比率随着蚁丘被破坏程度的增大而增大。当蚁丘体积被破坏75%时分巢比率最高,为14.44%;被破坏100%时搬巢比率、移巢比率均最高,分别为16.27%、27.00%。红火蚁蚁丘被破坏程度(D)与蚁群迁移比率(M)之间关系模型为M=4.3443+25.474D-3.4857D2。蚁丘受到破坏后,蚁群迁移距离平均为4.3m,迁移方向是随机的。     

Bait matrix for delivery of chitin synthesis inhibitors to the formosan subterranean termite (Isoptera: Rhinotermitidae)

The efficacy of three chitin synthesis inhibitors, diflubenzuron, hexaflumuron, and chlorfluazuron, incorporated into a novel bait matrix to kill the Formosan subterranean termite, Coptotermes formosanus Shiraki, was evaluated in the laboratory. The bait matrix was significantly preferred by C. formosanus over southern yellow pine wood in a two-choice feeding test. Bait formulations containing 250 ppm of the three chitin synthesis inhibitors were presented to termite nests with 2,500 individuals (80% workers and 20% soldiers) in the presence of alternative food sources consisting of cardboard and southern yellow pine, Pinus taeda L., wood. None of the bait formulations were significantly repellent or feeding deterrent to the termite workers evidenced by the lack of full consumption of alternative food sources. All nests presented with the bait formulations died within 9 wk, whereas the control nests (bait with no chitin synthesis inhibitors) remained alive 6 mo after the end of the study. No significant differences in consumption were observed among the chitin synthesis inhibitor treatments. Importance of this study for the improvement of current bait technology is discussed.     

Influence of toxic bait type and starvation on worker and queen mortality in laboratory colonies of Argentine ant (Hymenoptera: Formicidae)

The efficacy of toxic baits should be judged by their ability to kill entire ant colonies, including the colony queen or queens. We studied the efficacy of four toxic baits to the Argentine ant, Linepithema humile (Mayr) (Hymenoptera: Formicidae). These baits were Xstinguish that has the toxicant fipronil, Exterm-an-Ant that contains both boric acid and sodium borate, and Advion ant gel and Advion ant bait arena that both have indoxacarb. Experimental nests contained 300 workers and 10 queen ants that were starved for either 24 or 48 h before toxic bait exposure. The efficacy of the toxic baits was strongly influenced by starvation. In no treatment with 24-h starvation did we observe 100% worker death. After 24-h starvation three of the baits did not result in any queen deaths, with only Exterm-an-Ant producing an average of 25% mortality. In contrast, 100% queen and worker mortality was observed in colonies starved for 48 h and given Xstinguish or Exterm-an-Ant. The baits Advion ant gel and Advion ant bait arena were not effective against Argentine ants in these trials, resulting in <60% mortality in all treatments. Because of the strong influence of starvation on bait uptake, control efficacy may be maximized by applying bait when ants are likely to be starved. Our results suggest queen mortality must be assessed in tests for toxic bait efficacy. Our data indicate that of these four baits, Xstinguish and Exterm-an-Ant are the best options for control of Argentine ants in New Zealand.     

Evaluation of treatment success and patterns of reinfestation of the Formosan subterranean termite (Isoptera: Rhinotermitidae)

Spread of the Formosan subterranean termite, Coptotermes fornwsanus Shiraki (Isoptera: Rhinotermitidae), is connected with the transport of infested wood, in particular, railroad ties. Therefore, efficient treatment of infestations, especially along railroads, is imperative to prevent further termite damage and spread. Evaluation of treatment success hinges on the ability to assign infestation sites to colonies and compare colony identity before and after treatment. Because colonies of the Formosan subterranean termite can be headed by a pair of reproductives (simple families) or by multiple reproductives (extended families), the question arises whether the breeding system of a colony influences treatment success and whether treatment of an area might have an impact on the breeding system. We used microsatellite genotyping to compare colony affiliation and breeding systems of Formosan termites infesting the Riverfront Railroad, New Orleans, LA, before and after treatment with 0.5% noviflumuron. Before treatment, four colonies were simple families, and 11 colonies were extended families. A year after treatment began, all treated colonies had vanished and did not reappear during this study. One colony from an untreated monitoring station moved into a nearby station after treatment. Colonies that were detected after treatment consisted of 12 simple families and six extended families; extended families found after treatment contained a higher number of reproductive neotenics than the extended families found before treatment. Extended families were more likely than simple families to move into inground stations that had been previously occupied by termite colonies.