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At least 127 records · Page 7Linked to original sources
PubMed2002

Effect of tolerance to insecticides on substrate penetration by Formosan subterranean termites (Isoptera: Rhinotermitidae).

Seven selected insecticides were applied to three substrates and bioassayed for barrier efficacy and toxicity against the Formosan subterranean termite, Coptotermes formosanus Shiraki, originating from colonies that differed in their tolerance to the insecticides. A profound substrate effect was seen with all insecticides tested. Sand was the most difficult substrate to penetrate and caused faster and greater mortality of C. formosanus. Increased tolerance in C. formosanus was accompanied by a decrease in penetration of treated substrata with chlordane, methoxychlor, chlorpyrifos, and deltamethrin. The opposite was true in the case of permethrin and bendiocarb. More tolerance C. formosanus displayed decreased mortality in the presence of chlorpyrifos, deltamethrin, bendiocarb, and fipronil. The opposite was true for permethrin.

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PubMed2003

Effect of imidacloprid tree treatments on the occurrence of Formosan subterranean termites, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), in independent monitors.

Periodic sampling of 87 independent monitors, initially active with the Formosan subterranean termite, Coptotermes formosanus Shiraki, was conducted. Monitors, located in eight sectors adjacent to seven buildings, were various distances (1-46 m) from 57 trees treated with 0.1% imidacloprid foam. Termites collected from six of the eight sectors showed latent mortality attributed to imidacloprid intoxication at all monitor-tree distances. Approximately 6 mo after treatment, termite populations had recovered in these sectors. Another sector showed termite population suppression for approximately 15 mo, followed by recovery. Imidacloprid tree treatments did not control C. formosanus populations in independent monitors adjacent to the treatments.

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PubMed2004

Disruption of reproductive activity of Coptotermes formosanus (Isoptera: Rhinotermitidae) primary reproductives by three chitin synthesis inhibitors.

Effects of the chitin synthesis inhibitors (CSIs) diflubenzuron, hexaflumuron, and lufenuron on the Formosan subterranean termite, Coptotermes formosanus Shiraki, primary reproductives were studied in the laboratory. Incipient colonies were established by collecting and pairing C. formosanus alates and placing them in dishes containing an artificial diet. Three groups of 56 colonies each were fed with a diet containing 10 ppm of one of each of the CSIs and were compared with a control group fed with an untreated diet. All eggs oviposited by treated young queens failed to hatch at the end of 6 mo. Estimated queen fecundity was significantly lower in the lufenuron treatment compared with the control group. Fecundity of hexaflumuron-treated queens did not differ significantly from that of queens from the control group and the other treatments. Adult mortality was significantly higher in the diflubenzuron and lufenuron treatments than in the control group at the end of 6 mo., but not in the hexaflumuron treatment. All the pairs died within 8 mo. in the diflubenzuron and lufenuron treatments, even after treatment was suspended at the end of 6 mo. Mortality in the hexaflumuron treatment was significantly higher than in the control group by the end of 9 mo. The three CSIs tested eliminated reproduction in C. formosanus by preventing egg hatching and induced adult mortality. Possible mechanisms by which CSIs induce termite adult death are discussed.

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PubMed2005

Effect of Summon Preferred Food Source on feeding, tunneling, and bait station discovery by the formosan subterranean termite (Isoptera: Rhinotermitidae).

This study evaluated the effect of Summon Preferred Food Source on feeding, tunneling, and bait station discovery by the Formosan subterranean termite, Coptotermes formosanus Shiraki. Bioassays were conducted to determine whether Summon disks affected the aggregation and feeding behavior of termites and to determine whether the presence of Summon disks caused increased recruitment of termites to wood blocks. When termites encountered the disk, they immediately clustered on top of the disk. Termites were observed aggregating on top of the disk throughout the experiment. Consumption of Summon disks was significantly greater than consumption of cardboard disks in paired choice tests. The presence of a Summon disk on top of a wood block caused a significant increase in consumption of the wood block. Bioassays also were conducted to determine whether water extracts of Summon disks affected termite behavior. Consumption of filter paper disks treated with a water extract of Summon disks was significantly greater than consumption of control filter paper disks. Termites tunneled through sand treated with a water extract of Summon disks faster than they tunneled through untreated sand. In a field test, the rate of infestation of monitoring stations with a Summon disk was 3 times greater than the rate of infestations of stations without a disk.

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PubMed2005

Tunneling and mortality of eastern and Formosan subterranean termites (Isoptera: Rhinotermitidae) in sand treated with thiamethoxam or fipronil.

Thiamethoxam and fipronil were examined for their termiticidal properties against the Formosan subterranean termite, Coptotermes formosanus Shiraki, and the eastern subterranean termite, Reticulitermes flavipes (Kollar). Concentrations > or =8 ppm thiamethoxam and > or =1 ppm fipronil provided an effective barrier against C. formosanus and R. flavipes. Sand was penetrated to some degree at all concentrations of thiamethoxam (0-800 ppm for C. formosanus and 0-1000 ppm for R. flavipes) and fipronil (0-64 ppm for both C. formosanus and R. flavipes) tested, indicating that both termiticides are nonrepellent. Thiamethoxam was found to be more toxic against C. formosanus than R. flavipes whereas fipronil showed similar toxicity for both species. Higher mortality prevented termites from penetrating the entire 5-cm segment of treated sand.

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PubMed2005

Time trends in mortality for thiamethoxam and fipronil against Formosan subterranean termites and eastern subterranean termites (Isoptera: Rhinotermitidae).

Time trends in mortality for the Formosan subterranean termite, Coptotermes formosanus Shiraki, and eastern subterranean termite, Reticulitermes flavipes (Kollar), were determined for thiamethoxam and fipronil. Filter paper treated with 50 ppm thiamethoxam led to >80% mortality in 2-4 d for R. flavipes, whereas 5 ppm thiamethoxam resulted in >80% mortality in 2-3 d for C. formosanus. Filter paper treated with 1 ppm fipronil resulted in >80% mortality in 5 d for R. flavipes and 9 d for C. formosanus, indicating that thiamethoxam is faster acting than fipronil. As concentration decreases for slow-acting termiticides, the time required for adverse effects to be fully expressed increases.

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PubMed2005

Impacts of soil moisture level on consumption and movement of three sympatric subterranean termites (Isoptera: Rhinotermitidae) in a laboratory assay.

Three subterranean termite species, Reticuliternes flavipes (Kollar), Reticulitermes tibialis Banks, and Reticulitermes virginicus (Banks), were collected from locations in northern Indiana and tested under laboratory conditions to determine whether preferential differences exist among species. Foraging behaviors and location of all three species were studied using a linear, three-dimensional assay with a soil moisture gradient (5, 15, 25, 35, 45, and 55% moisture by weight) and quantified by (1) consumption weights and (2) location counts. In a 7-d period, R. flavipes and R. tibialis consumed almost twice as much filter paper as R. virginicus. No significant difference in feeding was attributed to moisture level for R. tibialis, but there were differences for R. flavipes and R. virginicus. In terms of location of harborage, there were clear patterns associated with moisture level, as predicted using a Poisson distribution. Results from consumption and location data show unique patterns among species, and illustrate species-specific variation in feeding location and nesting preference in response to moisture. There are significant differences in movement patterns, consumption, and mortality among Indiana Reticulitermes according to the laboratory assay. These findings contribute to the overall understanding of midwestern Reticulitermes termites.

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PubMed2005

Feeding, uptake, and utilization of carbohydrates by western subterranean termite (Isoptera: Rhinotermitidae).

Western subterranean termite, Reticulitermes hesperus (Banks), prefers various mono-, di-, and trisaccharides, total feeding being the greatest on paper disks treated with 5% ribose followed by 3% xylose, 2% maltose, 2% fructose, 2% arabinose, and 2% ribose. In multiple choice tests, termites were not able to discriminate between 2% ribose, 2% fructose, 2% xylose, and 2% maltose. Termites readily take up [14C] sucrose in feeding studies. Most of the sucrose is used as an energy source for respiration (89.2%), a very small proportion remains within the termite (9.3%), and an even smaller amount is excreted as solid waste (1.5%). The amount of 14C label transferred to other colony members via trophallaxis, body contact, or grooming is small and directly dependent upon the time and numbers of donors and recipients. At day 15 postmixing, the percentage of transfer was highest, 14.4 and 15.1% for both 1:1 and 2:1 donor to recipient mixing ratios, respectively. The mean amount of labeled 14C received by recipients increased from seven disintegrations per minute (dpm) on day 2 to 30 dpm on day 15 for 1:1. Overall mean radioactivity recovered from recipient termites when mixed with donor termites at 1:1 ratio (20 dpm) was significantly less than (28 dpm) when mixed with donor termites at 2:1 ratio. Sugars act as phagostimulants to the termites at concentrations much higher to those that termites naturally encounter in wood. Termites readily metabolize carbohydrates such as sucrose, and thus their use in bait matrices may increase consumption and retention at bait stations.

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PubMed2005

Response of the Formosan subterranean termites (Isoptera: Rhinotermitidae) to baits or nonrepellent termiticides in extended foraging arenas.

Distance effects of three treatments, noviflumuron, fipronil, and thiamethoxam, against laboratory populations of the Formosan subterranean termite, Coptotermesformosanus Shiraki, were tested in extended foraging arenas with foraging distances of 50 m. The results showed that during the 10-wk test period, all termites were killed by noviflumuron baits, whereas the nonrepellent termiticides fipronil and thiamethoxam divided the laboratory populations into two groups after causing 25-35% worker mortality. The horizontal transfer of lethal effects of fipronil was < or = 5 m. For thiamethoxam, the distance of transfer was substantially shorter. Because of their dose-dependent lethal time, the nonrepellent termiticides did not fulfill the requirements of a liquid bait model.

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PubMed2005

Effect of imidacloprid soil treatments on occurrence of Formosan subterranean termites (Isoptera: Rhinotermitidae) in independent monitors.

Periodic sampling of 30 independent monitors, initially active with the Formosan subterranean termite, Coptotermes formosanus Shiraki, was conducted to evaluate the effects of soil treated with imidacloprid on nearby termite activity. Monitors were located adjacent (1-3 m) to the buildings. Soil around and under the buildings was treated with 0.05% imidacloprid. None of the termites collected showed latent mortality attributed to imidacloprid intoxication. Imidacloprid soil treatments did not measurably reduce C. formosanus populations adjacent to the treatments. Imidacloprid does not seem to fit the liquid-bait model.

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PubMed2006

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.

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PubMed2006

Response of Reticulitermes flavipes (Isoptera: Rhinotermitidae) to disturbance in laboratory arenas at different temperatures and soldier proportions.

This study examined the evacuation response of groups of Reticulitermes flavipes (Kollar) workers after disturbance in laboratory arenas across a range of temperatures (16, 21, and 27 degrees C) and soldier proportions (1, 3, and 5%). Groups of workers and soldiers were disturbed in a central chamber and then monitored during a 5-d period to examine the percentage that initially evacuated, percentage of evacuees that returned, time to evacuate, time to return, and rates (percentage per hour) of evacuation and return between different temperatures and between soldier levels. Disturbance response patterns were observed that generally consisted of partial evacuation followed by movement back into disturbed areas. General alarm responses were observed and initiated specific alarm responses that resulted in more termites eventually returning to disturbed areas than originally evacuated. The typical evacuation response was not observed in groups with 5% soldiers. Instead, clustering in disturbed areas replaced evacuation. Regression revealed significant correlations between temperature and evacuation time, return time, evacuation rate, and return rate, indicating that R. flavipes alarm behaviors are influenced by temperature. There was a significant correlation between soldier proportions and the percentage of evacuees returning to disturbed areas. Analysis of variance (ANOVA) revealed significant differences between temperatures in the time to evacuate, evacuation rate, time to return, and return rate. ANOVA also showed significant differences between soldier proportions in the mean percentage of evacuees from and the rate of return to disturbed areas. Our results demonstrate that temperature influences the rate, but not the magnitude, of alarm response, whereas the influence of soldiers may not be as important in the context of general alarm as specific alarm.

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PubMed2006

Toxicity, repellency, and transfer of chlorfenapyr against western subterranean termites (Isoptera: Rhinotermitidae).

Chlorfenapyr is a slow-acting insecticide against western subterranean termite, Reticulitermes hesperus Banks, when applied to sand. The LD50 at day 7 for workers is 29.98 ng per termite and considerably higher than that of chlorpyrifos (14.01), cypermethrin (3.21), and fipronil (0.16). Brief exposures to sand treated with chlorfenapyr resulted in dose-dependent mortality over a broad range of concentrations. Brief 1-h exposures to > or =75 ppm provided >88% kill of termites at day 7. Chlorfenapyr deposits did not repel termites, even at 300 ppm. Termites tunneled from 0.1 to 1.8 cm into sand treated with 10- to 300-ppm chlorfenapyr deposits, resulting in > or =70% mortality. Within 1 h after being exposed to 50 ppm chlorfenapyr, approximately 17% of the termites exhibited impaired responses to synthetic trail pheromone. By 4 h, nearly 60% of the workers were not able to follow a 10 fg/cm pheromone trail. There was a direct linear relationship of the uptake of [14C]chlorfenapyr as concentration and duration of exposure increased. The percentage of chlorfenapyr transferred to recipients varied from 13.3 to 38.4%. Donors exposed for 1 h transferred a greater percentage of chlorfenapyr than did donors exposed for 4 h. A 1-h exposure on 100-ppm deposits provided sufficient uptake to kill 100% of the donors and sufficient transfer to kill 96% of the recipients. There was not enough transfer for recipients to serve as secondary donors and kill other termites. Horizontal transfer is limited to contact with the original donor and by the decreased mobility of workers within 4-8 h after exposure to treated sand. The effectiveness of chlorfenapyr barrier treatments is primarily due to its nonrepellency and delayed toxicity.

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PubMed2006

Survey of metabolic reserves, stored uric acid, and water content from field populations of subterranean termites (Isoptera: Rhinotermitidae) from Georgia.

Total levels of uric acid, soluble proteins, lipid, glycogen, and body water were determined for Reticulitermes flavipes (Kollar) workers 24-72 h after field collection. In addition, levels of biological molecules were compared for termites collected from the same inspection ports within 24 h after field collection, and after laboratory captivity of 6 or 9 mo. Uric acid content, described in a previous study as steadily accumulating in R. flavipes termites in captivity, was found to be low or undetectable in workers tested after 6 or 9 mo in the laboratory.

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PubMed2006

Parasitism of subterranean termites (Isoptera: Rhinotermitidae: Termitidae) by entomopathogenic nematodes (Rhabditida: Steinernematidae; Heterorhabditidae).

In laboratory bioassays, Steinernema riobrave Cabanillas, Poinar and Raulston (355 strain), Steinernema carpocapsae (Weiser) (Mexican 33 strain), Steinernemafeltiae (Filipjev) (UK76 strain), and Heterorhabditis bacteriophora Poinar (HP88 strain) were all capable of infecting and killing three termite species, Heterotermes aureus (Snyder), Gnathamitermes perplexus (Banks), and Reticulitermes flavipes (Kollar) in laboratory sand assays. S. riobrave and S. feltiae caused low levels of Reticulitermes virginicus (Banks) mortality under the same conditions. At 22 degrees C, significant mortality (> or = 80%) of worker H. aureus and G. perplexus was caused by S. riobrave, in sand assays, indicating the need for further study. Because of the short assay time (3 d maximum), reproduction of the nematodes in the target host species was not recorded. All nematode species were observed to develop to fourth-stage juveniles, preadult stages, or adults in all termite species with the exception of R. virginicus. Only S. riobrave developed in R. virginicus. Nematode concentration and incubation time had significant effects on the mortality of worker H. aureus. S. riobrave consistently generated the highest infection levels and mortality of H. aureus in sand assays.

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PubMed2004

Soldier-like intercastes in the rotten-wood termite Hodotermopsis sjostedti (Isoptera: Termopsidae).

All termite species possess a distinct sterile-soldier caste in their colonies, although reproductive soldiers, with soldier characteristics and reproductive ability, have been reported from several species of the family Termopsidae. Such intercastes have been considered the primitive-soldier caste, and based on this many researchers have discussed the evolutionary origin of termite soldiers. We investigated whether such soldier-reproductive intercastes also exist in the Japanese rotten-wood termite Hodotermopsis sjostedti. Abnormal individuals with soldier-like characteristics were found and designated as soldier-like intercastes, which appeared to have both soldier and reproductive characteristics. Based on our morphometric analyses and histological examinations, we suggest that the developmental origin of this intercaste is a pseudergate, nymph or sixth-instar larva. In addition, the intercaste was found to have relatively well-developed gonads, although mature oocytes and spermatozoa were not found in female ovaries and male seminal vesicles, respectively. We conclude that the soldier-like intercaste of H. sjostedti does not have reproductive ability, which is different from all other known soldier-like intercastes in Termopsidae.

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PubMed2000

Prospects for the biological control of subterranean termites (Isoptera: rhinotermitidae), with special reference to Coptotermes formosanus.

Costs associated with subterranean termite damage and control are estimated to approach $2 billion annually in the United States alone. The Formosan subterranean termite, Coptotermes formosanus Shiraki, is one of the more economically important subterranean species. In recent years, the shortcomings associated with conventional chemical control methods have prompted policymakers and scientists to evaluate the potential for biological control of subterranean termites (C. formosanus in particular), that is, to determine the potential for natural enemies - predators, parasitoids and pathogens - to suppress termite populations. Ants are the greatest predators of termites, and may have a considerable local impact on termite populations in some areas of the world. A few parasitoids of termites are known, but their potential for regulating termite populations seems negligible. Characteristics of the colony, such as a protected, underground location (and, for the C. formosanus nest, its modular and dispersed nature), are likely to limit the impact predators and parasitoids have on subterranean termites. Thus, there seems little potential for use of these agents for subterranean termite control. For various reasons, pathogenic organisms, such as viruses, bacteria, Protozoa, nematodes and most fungi, have shown little promise for use in biological termite control. However, research suggests that strains of two well-studied, endoparasitic fungi, Beauveria bassiana and Metarhizium anisopliae, when employed in baiting schemes, may offer the potential for at least some measure of subterranean termite control, although their successful use is compromised by a number of inherent biological limitations and logistical problems that have yet to be solved. Although not strictly in the realm of classical biological control, recent studies suggest that natural products, such as ant semiochemicals and fungal metabolites (siderophores), or their synthetic analogues, eventually might find a use in termite control programmes as repellents or insecticides in wood treatments or soil applications if stable formulations can be developed.

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