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PubMedDate not supplied

[A comparison of the antibacterial activity of the parasporal bodies of different bacilli].

Solutions of the parasporal bodies of Bacillus sphaericus, B. laterosporus, and several B. thuringiensis subspecies display antibacterial activity showing the potential of membranotropic action of the body proteins. Comparison of the antibiotic effect of various delta-endotoxins of B. thuringiensis made it possible to identify highly active unique proteins. This approach forms the basis of goal-directed search for organisms sensitive to polypeptides of various bodies. It has already been established that delta-endotoxins of B. thuringiensis ssp. amagiensis cause the death of representatives of the fourth (in addition to the three previously known) order of insects, Isoptera.

Animals↗
PubMed1999

Locomotory waves of Koruga and Deltotrichonympha: flagella wag the cell.

We investigated the nature of the locomotory waves of Koruga and Deltotrichonympha, flagellates living symbiotically in the hindgut of the Australian termite Mastotermes darwiniensis. The locomotory waves consist of two components: metachronal waves of flagellar beating and undulations of the cell surface, which propagate synchronously with the same wavelength, frequency, and velocity. We asked, do body waves cause flagellar waves, or vice versa? Using video microscopy and selective inhibitors and drugs, we found that (1) the amplitude of flagellar waves remains constant independent of variations in the amplitude of body waves, (2) flagellar waves can occur in the complete absence of body waves, (3) flagellar waves can induce body waves on swollen regions, (4) inhibition of flagellar beating by dynein inhibitors causes disappearance of body waves, and (5) cytochalasin D induces changes in cell shape but does not inhibit locomotory waves. Therefore, flagellar waves are not produced passively by an active contractile system in the cell cortex; instead, metachronally beating flagella exert waves of pressure that induce passive undulations of a pliant cell surface. These results support Machemer's [1974] theoretical analysis of the data of Cleveland and Cleveland [1966: Arch. Protistenk. 109:39-63], who believed the opposite.

Animals↗
PubMed2006

Use of a tool-set by Pan troglodytes troglodytes to obtain termites (Macrotermes) in the periphery of the Dja Biosphere Reserve, southeast Cameroon.

At the northern periphery of the Dja Biosphere Reserve (southeastern Cameroon) we recorded a new use of a tool-set by Pan troglodytes troglodytes to prey on Macrotermes muelleri, M. renouxi, M. lilljeborgi, and M. nobilis. We recovered 79 puncturing sticks and 47 fishing probes at 17 termite nests between 2002 and 2005. The mean length of the puncturing sticks (n = 77) and fishing probes (n = 45) was 52 cm and 56 cm, respectively, and the mean diameter was 9 mm and 4.5 mm, respectively. Sixty-eight percent of 138 chimpanzee fecal samples contained major soldiers of four Macrotermes species. The chimpanzees in southeastern Cameroon appeared to be selective in their choice of plant material to make their tools. The tools found at our study site resemble those from other sites in this region. However, in southeastern Cameroon only one tool-set type was found, whereas two tool-set types have been reported in Congo. Our study suggests that, along with the different vegetation types and the availability of plant material around termite nests, the nest and gallery structure and foraging behavior of the different Macrotermes spp. at all Central African sites must be investigated before we can attribute differences in tool-use behavior to culture.

Animals↗
PubMed2004

Ultrastructure of posterior sternal glands of Macrotermes annandalei (Silvestri): new members of the sexual glandular set found in termites (Insecta).

In female alates of Macrotermes annandalei, two types of abdominal glands are involved in the secretion of sex pheromone. Tergal glands are found at the anterior margin of tergites 6-10 and posterior sternal glands (PSGs) are located at the anterior margin of sternites 6-7. The cytological features of both types of glands are quite similar. The fine structural organization of PSGs is studied more precisely and described for the first time. The glandular cuticle is pitted with narrow apertures corresponding to the openings of numerous subcuticular pouches. Several Class 3 glandular units open in each pouch. One canal cell and one secretory cell make an individual glandular unit. The canal cell is enlarged apically and is connected with the other canal cells to form a common pouch. Based on the structural features found in these glands, we propose a common secretory process for PSGs and tergal glands. During the physiological maturation of alates inside the nest, secretory vesicles amass in the cytoplasm of secretory cells, while large intercellular spaces collapse the cuticular pouches. At the time of dispersal flight, pouches are filled with the content of secretory vesicles while intercellular spaces are sharply reduced. After calling behavior, no secretion remains in the glands and pouches collapse again, while secretory cells are drastically reduced in size. The structure and the secretory processes of PSGs and tergal glands are compared to those of abdominal sexual glands known in termites.

Abdomen↗
PubMed2006

Plant-derived natural products exhibiting activity against formosan subterranean termites (Coptotermes formosanus).

The Formosan subterranean termite, Coptotermes formosanus Shiraki, is among the most devastating termite pests. Natural products derived from plant extracts were tested in a discovery programme for effective, environmentally friendly termite control agents. Among the natural products tested, vulgarone B (isolated from Artemisia douglasiana Besser), apiol (isolated from Ligusticum hultenii (Fern.) Calder & Taylor) and cnicin (isolated from Centaurea maculosa Lam.) exhibited significantly higher mortalities than in untreated controls in laboratory bioassay. These compounds are present at high levels in their respective plant sources and also possess other biological activities such as phytotoxic and antifungal properties.

Animals↗
PubMed2006

Juvenile hormone III, hydroprene and a juvenogen as soldier caste differentiation regulators in three Reticulitermes species: potential of juvenile hormone analogues in termite control.

The efficacy of juvenile hormone III (JH III) and two JH-mimicking compounds was compared in laboratory experiments with Reticulitermes lucifugus (Rossi), R. santonensis Feytaud and R. virginicus (Banks). Induction of presoldier, soldier and/or soldier-worker intercaste differentiation was taken as positive response to the treatment. The novel juvenogen, a fatty acid ester of a juvenoid alcohol, induced greatest soldier differentiation in all species tested, followed by hydroprene. JH III was less effective. Representatives of three Reticulitermes species showed similar trends in soldier induction rates. Differences in mortality in treatments of termites of the same species from different colonies with the same compound were observed and evidently were caused by differences in the conditions of respective colonies.

Animals↗
PubMed2006

Influence of Portland cement amendment on soil pH and residual soil termiticide performance.

Soil adjacent to new brick veneer work is likely to have a higher pH owing to the mixture of cement with the soil. In the Gainesville, FL, area, soil samples taken from such locations had a range of pH values from 9.0 to 10.1; similar soils used in bioassays had a pH of 5.6 before the addition of cement. Addition of 15 mg of Portland cement to 33 g of soil increased the pH to 6, and addition of 291 mg of Portland cement increased the pH to 9. The pH of soil amended with cement was stable for the first 5 months. After 10 months, soil pH values decreased from alkaline to near neutral in all cases. Eastern subterranean termite workers, Reticulitermes flavipes (Kollar), were exposed to the treated soil at pH 6-9 for 24 h, and percentage mortality was recorded at 5 days, 5 months and 10 months. Termite mortality significantly decreased at higher soil pHs for bifenthrin, chlorpyrifos, fipronil and imidacloprid treatments at 5 months and similarly for bifenthrin, permethrin, chlorpyrifos, fipronil and imidacloprid treatments at 10 months. There was an inverse linear relationship between soil pH and mortality. Increased soil pH diminished residual activity of termiticide in the following order: imidacloprid > fipronil > chlorpyrifos = bifenthrin > permethrin > cypermethrin.

Animals↗
PubMed2007

Synergistic effect of heartwood extractives and quaternary ammonium compounds on termite resistance of treated wood.

This study evaluates the synergistic effect of wood extractives and quaternary ammonium compounds (QACs) on the resistance to termites of several treated wood species. Wood specimens from different natural durability classes were extracted with either hot water alone or hot water + ethanol/benzene. The extracted and unextracted wood specimens were treated with either didecyldimethylammonium tetrafluoroborate (DBF) or commercial didecyldimethylammonium chloride (DDAC) solutions and then exposed to subterranean termites, Coptotermes formosanus Shiraki, for 3 weeks under laboratory conditions. The results showed that extractives of the heartwood portions of the wood species contributed to increased resistance against termite attack in the presence of either DBF or DDAC wood preservatives. The synergistic effect of wood extractives and DBF was much clearer with Pseudotsuga menziesii (Mirbel) Franco and Tsuga heterophylla Sarg wood samples. Further studies are needed for a better understanding of the synergism between wood extractives and either DBF or DDAC using both the sapwood and heartwood portions of the same wood species.

Animals↗
PubMed2002

Group effects on insecticide toxicity in workers of the Formosan subterranean termite, Coptotermes formosanus Shiraki.

Coptotermes formosanus workers were treated topically with insecticide and subsequently held individually or in groups to examine possible effects on insecticide toxicity. Chlorpyrifos, cypermethrin and chlordane toxicities were 1.4-, 1.5-, and 1.3-fold greater, respectively, among workers held in groups compared with those held individually after insecticide treatment. Experiments were conducted to examine how enhanced toxicity occurred among termites held in groups after topical insecticide treatment. When workers were treated topically with chlordane and immediately placed with untreated workers, significantly greater numbers of untreated workers were killed compared with controls at all ratios examined (insecticide-treated:untreated). These data indicated that workers treated topically with insecticide were capable of somehow transferring a lethal dose of insecticide to untreated workers confined in the vial. Chlordane was recovered from untreated workers which had been confined with chlordane-treated workers; significantly higher quantities of chlordane were recovered from dead workers exposed to chlordane-treated workers compared with surviving workers exposed to chlordane-treated workers. Possible mechanisms of insecticide transfer from insecticide-treated to untreated termites are discussed.

Animals↗
PubMed2003

Comparative effects of vetiver oil, nootkatone and disodium octaborate tetrahydrate on Coptotermes formosanus and its symbiotic fauna.

The potential of vetiver oil and nootkatone as wood treatments against Coptotermes formosanus Shiraki was examined by assessing the effects on termite tunneling, feeding activity and survival, and the consequences on the symbiont protozoa responsible for wood digestion. Comparisons were made with non-treated wood (control), wood treated with the borate compound Tim-Bor (a commonly used lumber preservative) and absence of a food source (starved termites), using choice and no-choice tests. All wood slices were prepared at the same time using a 10 g liter(-1) solution of each substance and were tested in four different sessions over one year to investigate longevity of the effects. Termites had to tunnel through sand to exploit the food sources, consisting of two wood slices, placed on opposite sides of the experimental enclosure. No-choice tests showed that in the presence of vetiver oil or nootkatone, tunneling activity was always the lowest; wood consumption, termite survival and flagellate numbers and species distribution were significantly different from the control and similar to the results obtained for starved termites and with Tim-Bor-treated wood. Nootkatone negatively affected termites for 12 months and was longer lasting than vetiver oil. In choice tests, when vetiver oil or nootkatone were present, termites exhibited a significant preference for non-treated wood. Our results confirmed both the toxicity and absence of repellency of Tim-Bor. Vetiver oil and especially nootkatone affected Formosan subterranean termites and their protozoa, acting as arrestants, repellents and feeding deterrents, and represent a promising natural alternative for the control of this invasive pest.

Animals↗
PubMed2004

Juvenogens as potential agents in termite control: laboratory screening.

Preliminary screening tests of eight juvenogens, fatty acid esters of two parent juvenoid alcohols, showed high juvenilizing effect in the termite Prorhinotermes simplex (Hagen). This effect is manifested by differentiation of termite workers into pre-soldiers, soldiers and/or soldier-intercastes ('soldiers'). Juvenogen 9 was tested with five other termite species: Zootermopsis angusticollis Hagen, Kalotermes flavicollis F, Cryptotermes declivis Tsai & Chen, Reticulitermes santonensis de Feytaud, and R flaviceps Oshima, and showed promising efficacy in force-feeding (FF) as well as in choice bioassays. In the economically important subterranean termites R santonensis and R flaviceps, after application of 0.5 mg ml(-1) in FF experiments ca 57 and 73%, respectively, of workers changed into soldiers. In Zootermopsis angusticollis application of 0.05 mg ml(-1) caused differentiation in 62% soldiers, and 57% soldiers differentiated after topical application of 1 microg of the tested compound per termite. Differentiation of excessive soldiers induced by a juvenile hormone-mimicking compound may cause disruption of the social structure and ultimately the death of the colony.

Animals↗
PubMed2005

Effect of chlorpyrifos and monocrotophos on locomotor behaviour and acetylcholinesterase activity of subterranean termites, Odontotermes obesus.

The acute toxicity of chlorpyrifos and monocrotophos to subterranean termites, Odontotermes obesus (Rambur), has been studied by a paper contact method. The LC50 values for chlorpyrifos and monocrotophos were 0.046 and 0.148 microg cm(-2), respectively. Chlorpyrifos was 3.22-fold more toxic than monocrotophos. The effect of the pesticides on locomotor behaviour (velocity) and head acetylcholinesterase (AChE: EC 3.1.1.7) activity was estimated in LC50-exposed termites at intervals of 4, 8, 12, 16, 20 and 24 h. Chlorpyrifos- and monocrotophos-treated termites showed, respectively, 97 and 88% reduction in locomotor behaviour (velocity) after 24 h. At all time intervals the chlorpyrifos-treated termites exhibited more AChE inhibition and showed greater distorted behaviour than those exposed to monocrotophos. In vitro studies indicated that the I50 value (50% inhibition) for chlorpyrifos against AChE was 8.75 times that of monocrotophos.

Animals↗
PubMed2002

Homosexual tandem running as selfish herd in Reticulitermes speratus: novel antipredatory behavior in termites.

We investigated the predator avoidance mechanism of post-swarming alates of the lower subterranean termite, Reticulitermes speratus Kolbe. In some lower termites, homosexual tandem running is observed in addition to ordinary heterosexual tandem running. An experiment designed to compare the risk of predation by a termite-hunting ant, Brachyponera chinensis Emery, showed that homosexual tandem running reduced the predation risk until termites encounter the opposite sex. Since an individual ant cannot capture two dealates at once, one of the two dealates forming a tandem can escape while the ant captures its partner. Therefore, the "post-encounter risk" of individuals running in tandem was lower than that of single individuals. The "encounter risk" with predatory ants was also examined using a mathematical model considering the increased detectability of the predator due to enhanced size of the prey unit. It was suggested that tandem running reduces the predation risk of both participants, even when the enhanced encounter risk was taken into account. In males, competition for the back position was often observed, and consequently, the male at the back was always larger than the male in front. When a male-male tandem encountered a female, the back male won the female more often than the front male. This result suggested that male-male tandem running should result in selection pressure in favor of vigorous males. In conclusion, tandem running decreases the individual predation risk through the dilution effect, and it also plays a role as a mechanism of indirect sexual selection.

Animals↗
PubMed2002

Soldier production strategy in lower termites: from young instars or old instars?

We constructed a mathematical model to explain from which instars soldiers should be produced to maximize the growth rate of a termite colony. The model is based on the demography of the lower termite's colony: many of them feed inside the nest. The model predicts the following: (1) When the colony is young (it still has enough food and needs a high ratio of soldiers to workers) it will produce soldiers from young instars. (2) When the colony is old (it does not have enough food any more and needs a lower ratio of soldiers to workers) it will produce soldiers from old instars. This prediction fits well with the fact investigated by past empirical researches. With the samples of colonies of Neotermes koshunensis, we measured the antennal joint number of soldiers of each colony. We plotted the antennal joint number (1) of the average and (2) of the maximum one for each colony, against the total number of colony members. For both in each colony, we confirmed the consistency between the model and the samples: as the colony matures, it produces soldiers from older instars. The model also explains why higher termites produce soldiers from fixed instars. Their life style, in which they go outside to collect food, does not require a change in their soldier production strategy.

Aging↗
PubMed2003

Self-organized criticality and emergent oscillations in models of termite architecture with crowding.

The termite architecture model of O'Toole et'al. (1999) is extended to incorporate arbitrary halting time-scales. It is shown that this also means that the assumption of synchronous building must be relaxed. Numerical simulations show that ordered nest architecture emerges under a wide range of time-scales but also that there is an optimal region of halting times. This optimal region is explained by the emergence of synchronized periods of termite activity. The correlation length of the building distribution is shown to diverge providing strong evidence that the model is self-organized critical.

Animals↗
PubMed2002

Phylogenetic relationships in Termitomyces (Family Agaricaceae) based on the nucleotide sequence of ITS: a first approach to elucidate the evolutionary history of the symbiosis between fungus-growing termites and their fungi.

Termitomyces constitutes a very poorly known genus of fungi whose essential characteristic is that all representatives of the genus are cultivated by termites (Macrotermitinae) in their nest and that all the fungi cultivated by termites belong to this genus. For the first time, the phylogenetic relationships of several African Termitomyces species was studied by the sequencing of their internal transcriber spacer region (ITS1--5.8S--ITS2). It appeared that this group is clearly monophyletic and belongs to the Tricholomataceae family. The total homology of the ITS zone of several Termitomyces symbionts of different termite genera indicated that the specific diversity of this group is in fact less important than previously supposed. Finally, the comparison between the Termitomyces phylogenetic tree and the taxonomic tree of Macrotermitinae showed that if for certain genera the hypothesis of termite/fungus coevolution is acceptable, it should not be applied for all symbiosis.

Agaricales↗