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PubMed2002

Studies on thermal degradation and termite resistant properties of chemically modified wood.

A series of experiments were carried out to examine the resistant capacity of a chemically treated hard wood, Anthocephalus cadamba (Roxb) Miq. to thermal and termite degradation. The treatment with thermosetting resins viz. urea formaldehyde (UF), melamine formaldehyde (MF) and phenol formaldehyde (PF) at 31-33 levels of weight percent gain (WPG) increased the strength property i.e. modulus of rupture (MOR) by 7.50-21.02% and stiffness i.e. modulus of elasticity (MOE) by 9.50-12.18% over the untreated one with no remarkable effect on specific gravity. The treated samples were found resistant to termite attack, while the untreated one was badly damaged by termites on 12 months' exposure to a termite colony. The thermal degradations of untreated and treated wood samples were studied using thermogravimetric (TGA) and differential thermogravimetric (DTG) techniques at heating rates 20 and 30 degrees C min(-1) in temperature range 30-650 degrees C. The treated wood was found to be thermally more stable than the untreated one.

Animals↗
PubMed2000

Evidence from multiple gene sequences indicates that termites evolved from wood-feeding cockroaches.

Despite more than half a century of research, the evolutionary origin of termites remains unresolved [1] [2] [3]. A clear picture of termite ancestry is crucial for understanding how these insects evolved eusociality, particularly because they lack the haplodiploid genetic system associated with eusocial evolution in bees, ants, wasps and thrips [4] [5]. Termites, together with cockroaches and praying mantids, constitute the order Dictyoptera, which has been the focus of numerous conflicting phylogenetic studies in recent decades [6] [7] [8] [9] [10] [11] [12]. With the aim of settling the debate over the sister-group of termites, we have determined the sequences of genes encoding 18S ribosomal RNA, mitochondrial cytochrome oxidase subunit II (COII) and endogenous endo-beta-1, 4-glucanase (EG) from a diverse range of dictyopterans. Maximum parsimony and likelihood analyses of these sequences revealed strong support for a clade consisting of termites and subsocial, wood-feeding cockroaches of the genus Cryptocercus. This clade is nested within a larger cockroach clade, implicating wood-feeding cockroaches as an evolutionary intermediate between primitive non-social taxa and eusocial termites.

Animals↗
PubMed2001

Purification and characterization of trans-permethrin metabolizing microsomal esterases from workers of the eastern subterranean termite, Reticulitermes flavipes (Kollar).

Three alpha-naphthyl acetate hydrolyzing esterase isozymes were purified from microsomes prepared from Reticulitermes flavipes workers. The two step process involved sequential preparative IEF followed by continuous elution preparative electrophoresis on a 5% non-denaturing polyacrylamide gel. The first IEF run resulted in 5.4-fold purification with a yield of 46.1%. Subsequent IEF further purified the esterases 14.3-fold and 12% yield. Preparative electrophoresis of the pooled IEF fractions produced three major peaks of alpha-naphthyl acetate hydrolyzing activity. The esterases were correspondingly designated microsomal esterase (ME) 1, ME 2, and ME 3 based on increasing molecular retention on a native PAGE gel. ME 1, ME 2, and ME 3 were acidic proteins with pI values of 4.61, 4.70, and 4.77, respectively. Molecular mass as determined by gel filtration chromatography of ME 1, ME 2, and ME 3 was 69, 64, and 62 kDa, respectively. SDS-PAGE gels produced a single band for each of the isozymes with a molecular mass of 63 kDa indicating that the esterases were monomers. Specific activities of ME 1, ME 2, and ME 3 increased with increasing pH and the enzymes were active over a broad temperature range (25-55 degrees C). The three purified isozymes were inhibited at low concentration by paraoxon (10(-10) M), chlorpyrifos (10(-6) M), DEF (10(-6) M), and PMSF (10(-6) M) indicating that they were "B" type serine esterases. Conversely, inhibition was not observed at 10(-4) M eserine, PHMB, or CaCl(2), further supporting the conclusion that the microsomal esterases were of the "B" type. None of the isozymes was inhibited by 10(-4) M imidacloprid, fipronil, or PBO. Quantitatively, ME 1, ME 2 and ME 3 metabolized t-permethrin at 21.8, 21.0, and 38.8 nmol/h/mg protein, representing a purification factor of 333-, 318-, and 591-fold over microsomes, respectively. The three isozymes produced the same type and number of t-permethrin metabolites.

Animals↗
PubMed2002

Dual cellulose-digesting system of the wood-feeding termite, Coptotermes formosanus Shiraki.

The distribution of endo-beta-1,4-glucanase (EG) components in the digestive system of the wood-feeding termite, Coptotermes formosanus Shiraki, was investigated by zymogram analysis using polyacrylamide gel electrophoresis, followed by N-terminal protein sequencing. EG components similar to glycoside hydrolase family (GHF) 9 members were restricted to the salivary glands, the foregut, and the midgut, whereas components similar to GHF7 members were confined to the hindgut where numerous cellulolytic flagellates were harbored. RT-PCR experiments revealed that five GHF9 EG mRNAs (1348 bp) homologous to other termite EGs were expressed in the salivary glands and the midgut. The crude extract prepared from the midgut as well as that from the hindgut produced glucose from crystalline cellulose. These data suggest that C. formosanus has two independent cellulose-digesting systems: one in the midgut where cellulose digestion is accomplished by endogenous cellulases and the other in the hindgut which makes use of other cellulases possibly from symbiotic flagellates.

Acrylic Resins↗
PubMed2002

Molecular cloning of lysozyme-encoding cDNAs expressed in the salivary gland of a wood-feeding termite, Reticulitermes speratus.

Two kinds of PCR-product cDNAs that encode premature lysozyme peptides (Rs-Lys1 and Rs-Lys2) were cloned from workers of a Japanese damp-wood termite, Reticulitermes speratus. The Rs-Lys1 and Rs-Lys2 cDNAs encoded deduced sequences of 170 and 164 amino acids, respectively. Alignment of these sequences with those of other insect lysozymes showed that the cDNAs encode lysozyme homologues with putative signal peptides, insertions eight amino acids long, and a relatively long C-terminus (13-17 amino acids). A maximum likelihood tree, constructed using the cDNA sequences, indicated that the termite lysozymes are related to those of mosquitoes and lepidopterans. Southern-blotting analysis identified single copies of these lysozyme genes in the termite. Reverse transcript (RT)-PCR and in situ hybridization experiments showed that Rs-Lys1 and Rs-Lys2 are expressed in the salivary glands of worker termites. Here, we discuss the possible digestive function of these lysozymes.

Amino Acid Sequence↗
PubMed2002

A digestive beta-glucosidase from the salivary glands of the termite, Neotermes koshunensis (Shiraki): distribution, characterization and isolation of its precursor cDNA by 5'- and 3'-RACE amplifications with degenerate primers.

beta-Glucosidase activity [EC 3.2.1.21] was measured in the salivary glands and the gut of wood-eating termite, Neotermes koshunensis (Shiraki). 75% of the activity was detected in the salivary glands, whereas 15% of the activity was present in the hindgut, where numerous symbiotic flagellates reside. The salivary beta-glucosidase was partially purified by ion-exchange and gel filtration chromatography. The molecular weight of the salivary beta-glucosidase was 60 kDa, and the K(m) value on cellobiose was 2.5 mM. Its optimal pH was 5.6 and the activity was stable from 20 degrees C up to 45 degrees C. In addition to cellobiose, p-nitrophenyl-beta-D-fucopyranoside and laminaribiose were efficiently hydrolyzed by the salivary beta-glucosidase. Degenerate PCR using primers designed from N-terminal amino acid sequences of the salivary beta-glucosidase resulted in a cDNA fragment of 1730 bp, encoding 498 amino acids and with sequence similarity to glycosyl hydrolase family 1. Reverse-transcription (RT)-PCR showed that this beta-glucosidase is produced only in the salivary glands.

3' Untranslated Regions↗
PubMed2002

Fatty acid esters of juvenoid alcohols as insect hormonogen agents (juvenogens).

A series of 8 new juvenogens (3--10) was prepared starting from a pair of isomeric insect juvenile hormone bioanalogues ( and ). The biological activity of the juvenogens -- was tested for their effect on reproduction of the blowfly Neobellieria (Sarcophaga) bullata and for the juvenilizing activity on the termite Prorhinotermes simplex. Results of biological screening are important in structure--activity studies and promising for potential practical application of some of the juvenogens studied, especially against termites.

Animals↗
PubMed2000

Cyclic carbon dioxide release in the dampwood termite, Zootermopsis nevadensis (Hagen).

Real-time traces of CO(2) release of pseudergates of the dampwood termite, Zootermopsis nevadensis (Hagen) were obtained using flow-through respirometry. Traces were made at each of six temperatures, between 10 and 35 degrees C. Termites released CO(2) in a cyclic pattern at each of the six temperatures. CO(2) release rate (as V(CO(2)) in ml h(-1)) increased significantly with temperature and body mass. Rate of change in V(CO(2)) with temperature (or Q(10)) was 2.11. Degree of cycling in CO(2) traces was estimable using the coefficient of variability. Coefficient of variability for both acyclic and cyclic traces declined exponentially with increasing temperature.

Animals↗
PubMed2000

Microecology of the termite gut: structure and function on a microscale.

Long considered simply as anoxic fermentors, termite guts are in fact axially and radially structured environments with physicochemically distinct microhabitats. Recent developments in termite gut microecology, which combined traditional and modern techniques, have focused on the spatial organization of important microbial populations and their in situ activities, and have significantly furthered our understanding of functional interactions within highly structured microenvironments.

Animals↗
PubMed2002

Insecticide susceptibility and detoxication enzyme activities among Coptotermes formosanus Shiraki workers sampled from different locations in New Orleans.

Coptotermes formosanus Shiraki worker termites were sampled from 20 locations in the City Park area of New Orleans, LA. The termites were subsequently assayed to determine their susceptibility to cypermethrin, chlordane and chlorpyrifos, and detoxication enzyme activity. Cypermethrin was most toxic against Formosan subterranean termite workers, chlorpyrifos exhibited intermediate toxicity and chlordane was least toxic. A comparison of insecticide susceptibility between the most and least tolerant colonies revealed 1.9-, 1.7- and 1.8-fold differences in susceptibility for cypermethrin, chlorpyrifos and chlordane, respectively. As with the bioassay data, although significant differences were noted, a great deal of overlap was observed among the colonies for total cytochrome P450 content (difference of 2.2-fold between high and low value) aldrin epoxidation (3.6-fold) and cytosolic esterase (3.9-fold) activity. No significant differences were observed among the colonies for methoxyresorufin O-demethylase or glutathione S-transferase activity. Conversely, microsomal esterase activity varied greatly; a 38-fold difference was observed between the most (Cf1776) and least (Cf1387) active colonies. However, no significant correlation was observed between insecticide susceptibility and microsomal esterase activity. In fact, no significant correlations were observed between any of the enzyme activities measured and insecticide susceptibility. These results are discussed in the context of insecticide selection and future control effectiveness.

Animals↗
PubMed2003

Phylogenetic relationships of Termitomyces and related taxa.

Phylogenetic relationships of termitophilic fungi were estimated with Bayesian as well as other phylogenetic methods from partial sequences of the nuclear encoded large subunit ribosomal DNA (nLSU-rDNA) and the mitochondrial encoded small subunit ribosomal DNA (mtSSU-rDNA). Sequences were obtained from basidiomes covering the morphological, taxonomical, and geographical span of termitophilic mushroom-forming fungi, and analysed together with sequences from termite nests and termite guts from most known genera of fungus growing termites from geographically diverse regions. Topologies of trees resulting from the combined analyses of the two ribosomal genes generally show no positive conflicts with those obtained from separate analyses. We show that termitophilic fungi constitute a strongly supported monophyletic group within lyophylloid species. The genera Sinotermitomyces and Podabrella are derived within Termitomyces, and do not form monophyletic groups. Identical sequences were frequently found among samples of basidiomes from the same continents and among fungi utilized by termites from the same continent. However, only two sequences were identical between basidiome samples and termite nest/gut samples suggesting fruiting species do not form a representative sample of termitophilic fungi. No sequences were identical between samples from Asia and Africa indicating some geographic differentiation between these continents.

Animals↗
PubMed2005

Termitomyces sp. associated with the termite Macrotermes natalensis has a heterothallic mating system and multinucleate cells.

Fungi of the genus Termitomyces live in an obligate symbiosis with termites of the subfamily Macrotermitinae. Many species of Termitomyces frequently form fruit bodies, which develop from the fungus comb within the nest. In this study, we determined the mating system of a species of Termitomyces associated with the South African termite Macrotermes natalensis. Termite nests were excavated and a Termitomyces sp. was isolated into pure culture from the asexual fruit bodies (nodules) growing in the fungus gardens. For one strain, single basidiospore cultures were obtained from basidiomes growing from the fungus comb after incubation without termites. Using nuclear staining, we show that both comb cultures and single spore cultures have multinucleate cells and that the majority of spores has a single nucleus. However, DNA sequencing of the ITS region in the nuclear RNA gene revealed that the comb mycelium had two different ITS types that segregated in the single spore cultures, which consequently had only a single ITS type. These results unambiguously prove that the strain of Termitomyces studied here has a heterothallic mating system, with the fungus garden of the termite mound being in the heterokaryotic phase. This is the first time the mating system of a Termitomnyces species has been studied.

Animals↗
PubMed2002

Carbon isotope signature of polycyclic aromatic hydrocarbons (PAHs): evidence for different sources in tropical and temperate environments?

In tropical soils, naphthalene and, partly also, perylene occur at elevated concentrations while pyrolytic higher molecular weight PAHs are almost absent. We hypothesize that there are recent biological PAH sources in the tropical environment related with woody plants and termites. We used the C isotope signature of individual PAHs in temperate and tropical soils and in tropical wood and termite nests to distinguish different PAH sources. The mean delta13C values of the benzo[b+j+k]fluoranthenes and of benzo[a+e]pyrenes in temperate soils ranged between -24.6/1000 and -25.3/1000, being similar to values reported in the literature for PAHs with pyrolitic origin. The mean delta13C values of perylene decreased in the order temperate soils (-27.0/1000) > termite nests (-31.4/1000) > tropical soil (-32.4/1000), while those of naphthalene (-24.6/1000 to -26.2/1000) were similar among the tropical and temperate soils, tropical wood, and termite nests. Our results support the assumption that perylene in the tropical environment is recently biologically produced, as indicated by the depletion in 13C. The C isotope composition of naphthalene, however, cannot be used to distinguish different sources.

Animals↗
PubMed2001

Preparation of pentachlorophenol derivatives and development of a microparticle-based on-site immunoassay for the detection of PCP in soil samples.

Pentachlorophenol (PCP) is used as a herbicide in agriculture and as an insecticide for termite control. Because of the apparent hazard associated with its usage, there is a need for an efficient and economic on-site screening method. A 5-min on-site test has been developed for the detection of PCP based on the OnTrak format, a successful Roche on-site test format for drugs of abuse, utilizing the principle of latex agglutination immunoassay. The test detects 1 ppm of PCP in soil samples.

Agglutination Tests↗
PubMed2001

Stability of chlorpyrifos for termiticidal control in six Australian soils.

Chlorpyrifos [O,O-diethyl O-(3,5,6-trichloro-2-pyridyl) phosphorothioate] is the most widely used soil-applied termiticide in Australia. It is relatively stable, has low water solubility, is absorbed by organic matter, and has a high affinity for soil with low partitioning potential from soil matter to soil water. The purpose of this degradation study is to determine the effect of soil alkalinity on the longevity of termite protection when chlorpyrifos is applied as a termiticide in a range of Australian soils, particularly high-pH substrates. The study also examines the effects of initial soil concentration on the degradation of chlorpyrifos in the range of soils. At an initial soil concentration of 1000 mg kg(-)(1) for termite control, the degradation rate of chlorpyrifos is very strongly retarded in soils tested when compared with lower soil concentrations of 100 and 10 mg kg(-)(1) in the same soils. The degradation data correlated with a logarithmic model of decay, and it was thus possible to produce half-lives and predict likely periods of termite control. Average half-lives for all soils for the three concentrations were 385, 155, and 41 days, respectively. Soil pH had no effect on the rate of degradation at all concentrations tested.

Animals↗
PubMed2002

Antitermitic activity of leaf essential oils and components from Cinnamomum osmophleum.

The antitermitic activities of the essential oils from the leaves of two Cinnamomum osmophloeumclones (A and B) and their chemical ingredients against Coptotermes formosanus Shiraki were investigated according to direct contact application. Results from this experiment have demonstrated that the indigenous cinnamon B leaf essential oil has a more effective antitermitic activity than indigenous cinnamon A leaf essential oil. Furthermore, when cinnamaldehyde, eugenol, and alpha-terpineol are extracted from indigenous cinnamon leaf essential oil and used at the strength of 1 mg/g, their antitermitic effectiveness is much higher than that using indigenous cinnamon leaf essential oil. Among the congeners of cinnamaldehyde examined, cinnamaldehyde has exhibited the strongest termiticidal property.

Acrolein↗