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At least 271 records · Page 15Linked to original sources
PubMed2005

Regulation of juvenile hormone titers by soldiers in the Formosan subterranean termite, Coptotermes formosanus.

In field collections of the Formosan subterranean termite Coptotermes formosanus, soldiers averaged less than 10%. The proportion of soldiers increased to about 25% or higher when termites were kept in the laboratory, as did the juvenile hormone III (JH III) titers for both workers and soldiers. In laboratory experiments with a proportion of soldiers 25% or higher, very few new pre-soldiers were formed and the JH titer in existing soldiers remained constant. On the contrary, workers from groups containing less than 25% soldiers formed more pre-soldiers. In such cases, both workers and soldiers showed higher JH titers. Newly formed soldiers also had higher JH titers than older soldiers. It is speculated that populations containing higher soldier proportions inhibit further soldier differentiation, eventually holding the JH titers under the threshold or suppressing the activity of corpora allata resulting in lower JH titers in workers.

Animals↗
PubMed2005

Endocrine changes in maturing primary queens of Zootermopsis angusticollis.

Termite queens are highly specialized for reproduction, but little is known about the endocrine mechanisms regulating this ability. We studied changes in the endocrinology and ovarian maturation in primary reproductive females of the dampwood termite Zootermopsis angusticollis following their release from inhibitory stimuli produced by mature queens. Winged alates were removed from their natal nest, manually dewinged, then paired in an isolated nest with a reproductive male. Development was tracked by monitoring ovarian development, in vitro rates of juvenile hormone (JH) production by corpora allata, and hemolymph titers of JH and ecdysteroids. The production rate and titer of JH were positively correlated with each other but negatively correlated with ecdysteroid titer. Four days after disinhibition, JH release and titer decreased while ecdysteroid titer increased. The new levels persisted until day 30, after which JH increased and ecdysteroids decreased. Fully mature queens had the highest rates of JH production, the lowest ecdysteroid titers, and the greatest number of functional ovarioles. The results support the hypothesis that JH plays a dual role in termite queens depending on their stage of development; an elevated JH titer in immature alates may maintain reproductive inhibition, but an elevated JH titer in mature queens may stimulate ovarian activity. The decline in JH production and the elevation in ecdysteroid titer correspond to a period of physiological reorganization and activation. The specific function of ecdysteroids is unknown but they may help to modulate the activity of the corpora allata.

Animals↗
PubMed2005

Evaluation of novel and traditional measures for vigor of laboratory-cultured termites, Reticulitermes flavipes (Kollar).

The current study was undertaken to consider predictive methods for describing the vigor of Reticulitermes flavipes (Kollar) termites stored in a laboratory under conditions similar to control groups in bioassay. These novel methods were based on measurements for levels of biological molecules (uric acid, soluble proteins, lipid, and glycogen), percent water content, live weight, and running speed. Also considered were two established, non-predictive methods for determining vigor, survivorship and consumption rate. Of the novel measures tested, lipid and body water percentage show promise in distinguishing weak from vigorous groups of termites, with body water percentage a more practical means of measurement. Low body water percentage was concluded to be an indicator of weak groups of termites.

Animals↗
PubMed2004

Magnetic material arrangement in oriented termites: a magnetic resonance study.

Temperature dependence of the magnetic resonance is used to study the magnetic material in oriented Neocapritermes opacus (N.o.) termite, the only prey of the migratory ant Pachycondyla marginata (P.m.). A broad line in the g = 2 region, associated to isolated nanoparticles shows that at least 97% of the magnetic material is in the termite's body (abdomen + thorax). From the temperature dependence of the resonant field and from the spectral linewidths, we estimate the existence of magnetic nanoparticles 18.5+/-0.3 nm in diameter and an effective magnetic anisotropy constant, K(eff) between 2.1 and 3.2 x 10(4)erg/cm(3). A sudden change in the double integrated spectra at about 100K for N.o. with the long body axis oriented perpendicular to the magnetic field can be attributed to the Verwey transition, and suggests an organized film-like particle system.

Abdomen↗
PubMed2005

The role of logistic constraints in termite construction of chambers and tunnels.

In previous models of the building behaviour of termites, physical and logistic constraints that limit the movement of termites and pheromones have been neglected. Here, we present an individual-based model of termite construction that includes idealized constraints on the diffusion of pheromones, the movement of termites, and the integrity of the architecture that they construct. The model allows us to explore the extent to which the results of previous idealized models (typically realised in one or two dimensions via a set of coupled partial differential equations) generalize to a physical, 3-D environment. Moreover we are able to investigate new processes and architectures that rely upon these features. We explore the role of stigmergic recruitment in pillar formation, wall building, and the construction of royal chambers, tunnels and intersections. In addition, for the first time, we demonstrate the way in which the physicality of partially built structures can help termites to achieve efficient tunnel structures and to establish and maintain entrances in royal chambers. As such we show that, in at least some cases, logistic constraints can be important or even necessary in order for termites to achieve efficient, effective constructions.

Animals↗
PubMed2006

Food encounter rates of simulated termite tunnels with variable food size/distribution pattern and tunnel branch length.

Subterranean termites excavate tunnels in a search pattern to encounter food in soil. To investigate the effect of food size, food distribution and the branch length of tunnels on food encounter rate we used a lattice gas model to simulate tunnels of the Formosan subterranean termite, Coptotermes formosanus Shiraki. The model made use of minimized local rules derived from empirical data to simulate termite tunnel patterns in featureless soil. Food distributions with three types (uniform, random, and clumped) were defined by using an I-index proposed by Zimmer and Johnson (1985). The food encounter rate was higher in a clumped than in non-clumped (uniform and random) distribution of food particles. When food particle size was varied in random distributions of food particles a maximum encounter rate was found, with particles of larger or smaller size being encountered less frequently. We also discussed the relationship between the branch tunnel length and the tunnel search pattern in minimizing the redundancy of overlapping branches.

Animals↗
PubMed2006

Characterization of a newly discovered China variety of Metarhizium anisopliae (M. anisopliae var. dcjhyium) for virulence to termites, isoenzyme, and phylogenic analysis.

The efficacy of a new virulent Metarhizium anisopliae variety (M. anisopliae var. dcjhyium, DQ288247) obtained from Odontotermes formosanus in China was evaluated against the subterranean termite, O. formosanus, in the laboratory. The new variety was compared with four other virulent M. anisopliae isolates and was found to be highly infectious and virulent against termites. M. anisopliae var. dcjhyium could cause approximately 100% mortality of termites 3 days post-inoculation in the concentration of 3x10(8) conidia/ml. There were also differences in relative hyhal growth and isoenzymes. M. anisopliae var. dcjhyium showed a different isoenzyme band pattern from the four isolates of M. anisopliae (AB027337, AB099510, AB099941 and AF280631). The phylogenetic tree of the 18S rDNA sequences revealed the taxonomic and evolutionary position of M. anisopliae var. dcjhyium. M. anisopliae var. dcjhyium and four isolates of M. anisopliae formed a monophyletic group, supported by a 99% bootstrap value. M. anisopliae var. dcjhyium formed a distinct variety, which had a special characterization of unique bands of isoenzyme, high virulence and low repellency against termites when compared with four other isolates of M. anisopliae.

Animals↗
PubMed2004

Antitermitic quinones from Diospyros sylvatica.

Six quinones were isolated from the chloroform extract of the roots of Diospyros sylvatica and identified as 2-methyl-anthraquinone, plumbagin, diosindigo, diospyrin, isodiospyrin and microphyllone. The effect of the root extract on the orientation and survival of the subterranean termite, Odontotermes obesus was tested. In addition, four of these quinones were tested on the survival of the subterranean termite. In a direct-choice experiment, exposure to an extract-treated filter disc had a significantly repellent effect over the solvent-treated filter disc. The no-choice experiment revealed the toxic property of the extract as well as the tested quinones and showed high mortality of the O. obesus workers after 48 h on forced exposure. The major termiticidal components identified were plumbagin, isodiospyrin and microphyllone while diospyrin was not toxic to termites at the concentration tested. All the quinones are reported for the first time from D. sylvatica.

Animals↗
PubMed2006

Fluorescent pseudomonads occurring in Macrotermes subhyalinus mound structures decrease Cd toxicity and improve its accumulation in sorghum plants.

Cd-tolerant bacterial strains of fluorescent pseudomonads, mostly belonging to Pseudomonas monteillii, were isolated from termite mound soil (Macrotermes subhyalinus, a litter-forager and fungus-growing termite), in a Sudanese shrubby savanna, Burkina Faso. Such large mounds appeared as sites of great bacterial diversity and could be considered as hot spots of metal-tolerant fluorescent pseudomonads. Microbial isolates were inoculated to Sorghum plants (S. bicolor) in glasshouse experiments with soil amended with CdCl(2) (560 mg Cd kg(-1) soil). Microbial functional diversity was assessed at the end of the experiment by measurement of in situ patterns of catabolic potentials. All the bacteria isolates significantly improved the shoot and total biomass of sorghum plants compared to the control. Results concerning root biomass were not significant with some strains. Arbuscular mycorrhiza (AM) was greatly reduced by CdCl(2) amendment, and fluorescent pseudomonad inoculation significantly increased AM colonisation in the contaminated soil. The bacterial inoculation significantly improved Cd uptake by sorghum plants. Measurement of catabolic potentials on 16 substrates showed that the microbial communities were different according to the soil amendment. Soils samples inoculated with pseudomonad strains presented a higher use of ketoglutaric and hydroxybutiric acids, as opposed to fumaric acid in soil samples not inoculated. It is suggested that fluorescent pseudomonads could act indirectly in such metabolic processes by involving a lower rate of degradation of citric acid, in line with the effect of small organic acid on phytoextraction of heavy metals from soil. This is a first contribution to bioremediation of metal-contaminated sites with soil-to-plant transfer, using termite built structures. Further data are required on the efficiency of the bacterial strains isolated and on the processes involved.

Animals↗
PubMed2006

Occurrence of rhizobia in the gut of the higher termite Nasutitermes nigriceps.

Wood-eating termites feed on a diet highly deficient in nitrogen. They must complement their diet with the aid of nitrogen-fixing bacteria. Nitrogen fixation in the gut has been demonstrated, but information about nitrogen-fixing bacteria in pure culture is scarce. From the higher termite Nasutitermes nigriceps the symbiotic bacterial strain M3A was isolated, which thrives in the hindgut contents. The Gram-negative strain exhibited similarities to the species of the genus Ensifer (including Sinorhizobium) on the basis of morphological and physiological/biochemical features. The 16S rRNA gene analysis showed the highest sequence similarity of the isolate M3A to Ensifer adhaerens (>99%; ATCC 33499). The DNA-DNA hybridization revealed a similarity of 66% with E. adhaerens (NCIMB12342(T)). In contrast to the type strain the isolate M3A possesses the capacity to nodulate plant roots. This is the first report on the detailed identification of a rhizobia-related strain from the intestinal tract of animals. Strain M3A has been deposited with two culture collections (DSM10169; ATCC BAA-396).

Animals↗
PubMed2004

The biological activity in mammals and insects of the nucleosidic fraction from the spider Parawixia bistriata.

Previous work has shown that the crude venom of Parawixia bistriata induces convulsive seizures in rats after intracerebroventricular injection. In this work, the isolation of a bioactive fraction with ultraviolet absorption characteristics of nucleic acid and trace protein or amino acid content is described. NMR analysis demonstrated that the major component of the active fraction is the nucleoside inosine. An analogue of this component (inosine 5'-monophosphate) induced a delayed paralysis effect in termites.

Animals↗
PubMed2005

Molecular phylogeny of parabasalids inferred from small subunit rRNA sequences, with emphasis on the Hypermastigea.

Small subunit rRNA gene sequences were identified without cultivation from parabasalid symbionts of termites belonging to the hypermastigid orders Trichonymphida (the genera Hoplonympha, Staurojoenina, Teranympha, and Eucomonympha) and Spirotrichonymphida (Spirotrichonymphella), and from four yet-unidentified parabasalid symbionts of the termite Incisitermes minor. All these new sequences were analyzed by Bayesian, likelihood, and parsimony methods in a broad phylogeny including all identified parabasalid sequences available in databases and some as yet unidentified sequences probably derived from hypermastigids. A salient point of our study focused on hypermastigids was the polyphyly of this class. We also noted a clear dichotomy between Trichonymphida and the other parabasalid taxa. However, this hypermastigid order was apparently polyphyletic, probably reflecting its morphological diversity. Among Trichonymphida, Teranympha (Teranymphidae) grouped together with the members of the family Eucomonymphidae, suggesting that its family status is ambiguous. The monophyletic lineage composed by Spirotrichonymphida exhibited a narrower branching pattern than Trichonymphida. The root of parabasalids was examined but could not be discerned accurately.

Animals↗
PubMed2001

Solid-phase microextraction for the detection of termite cuticular hydrocarbons.

Solid-phase microextraction (SPME)-gas chromatography-mass spectrometry was used to identify the cuticular hydrocarbons of the subterranean termite Coptotermes formosanus Shiraki. Headspace SPME and direct contact SPME methods were evaluated and compared to the hexane extraction method. Variables, such as temperature, time, number of termites, condition of the termites, and the type of SPME fiber were evaluated. Methods were refined to increase the reproducibility as well as the sensitivity. Both SPME methods were successfully used for the identification of all the major termite cuticular hydrocarbons. Using the headspace SPME method, other compounds of interest could also be identified, such as fatty acids. Using the direct contact SPME method, termites could be repeatedly studied over time to monitor chemical changes.

Animals↗
PubMed2003

Ecdysone agonist halofenozide affects corpora allata and reproductive physiology of the Formosan subterranean termite, Coptotermes formosanus.

Following a short swarming flight, winged adults of the Formosan subterranean termite, Coptotermes formosanus lose their wings and form tandem pairs. These dealates or primary reproductives then form incipient colonies. Topical application of 5 microg of the non-steroidal ecdysone agonist RH-0345 (halofenozide) in 0.1 microl DMSO to the primary reproductives during the 2000 season resulted in significant reduction in the number of eggs laid. There was however complete recovery of the treated females. Apparently the non-treated partner removed the treatment chemical while grooming indicating oral activity. In 2001 both topical application as well as feeding methods were tried. Significant effects were observed only in the topical treatment group, perhaps because of inconsistency in feeding. In this group, total progeny, the number of ovarioles in ovaries and the size of the female's corpora allata (CA) were all significantly reduced. Ultrastructure of the CA of treated females showed extensive vacuolation near the surface of the gland. The experiment was repeated in 2002 using both topical application and an improved oral feeding method. Whereas there was apparent recovery in the topically treated group after 90 days, the oral treatment was more persistent in its effect perhaps due to a higher amount of halofenozide consumed during feeding.

Administration, Oral↗