Evaluation of differential antitermitic activities of Lantana camara oven‐dried tissues against Reticulitermes virginicus (Isoptera: Rhinotermitidae)

Abstract Chemical‐treated soil or physical barriers have been the most commonly used approach for termite management. We hypothesized that a barrier of soil incorporated with oven‐dried Lantana camara L. tissues could prevent termite infestation. We first examined the antitermitic effects of the dried tissues from two cultivars (‘Mozelle’ and ‘New Gold’) on the subterranean termite, Reticulitermes virginicus (Banks) (Isoptera: Rhinotermitidae). Results show that all of the tissues of Mozelle had greater antitermic activity than corresponding tissues of New Gold, and leaves had greater termiticidal effects than flowers and stems. When termites were exposed to the test materials in a no‐choice bioassay, the 24‐day test resulted in a significant reduction of survival (52.5%–88.6%), running speed (18.2%–37.3%), live weight (21.8%–53.5%) and body water content (33.2%–56.2%) compared to the control. The consumption of leaves and flowers was exiguous. When used as 25% tissue mulch‐barrier, the oven‐dried lantana tissues decreased termite tunneling and wood consumption and increased termite mortality. The decreased survival, vigor, and low consumption indicate a toxic and anti‐feeding property of the materials tested. The results therefore support our hypothesis that the dried lantana tissues possess antitermitic activities.     

Purification and Characterization of Termite Endogenous β-1,4-Endoglucanases Produced in Aspergillus oryzae

Although termites are known to have a highly efficient lignocellulose-digesting system, mass production of native endogenous cellulases of termites has failed in Escherchia coli, and in Saccharomyces cerevisiae, and it has not been accomplished. Here we report the successful production, purification, and characterization of two termite endogenous β-1,4-endoglucanases, RsEG and NtEG, from the salivary gland of Reticulitermes speratus and the midgut of Nasutitermes takasagoensis respectively, using Aspergillus oryzae as host. Thin-layer chromatography analysis showed that both enzymes hydrolyzed the β-1,4-cellulosic linkage of cellodextrin into cellobiose and glucose. Kinetic studies indicated that the specific activity and Vmax values of the two enzymes were significantly higher than those of previously reported fungal and bacterial endoglucanases.     

Influence of Feed Components on Symbiotic Bacterial Community Structure in the Gut of the Wood-Feeding Higher Termite Nasutitermes takasagoensis

The influence of carbon sources on bacterial community structure in the gut of the wood-feeding higher termite Nasutitermes takasagoensis was investigated. 16S rRNA gene sequencing and terminal-restriction fragment length polymorphism (T-RFLP) analyses revealed that the bacterial community structure changed markedly depending on feed components at the phylum level. Spirochaetes was predominant in the clone libraries from wood- and wood powder-fed termites, whereas Bacteroidetes was the largest group in the libraries from xylan-, cellobiose-, and glucose-fed termites, and Firmicutes was predominant in the library from xylose-fed termites. In addition, clones belonging to the phylum Termite Group I (TG1) were found in the library from xylose-fed termites. Our results indicate that the symbiotic relationship between termite and gut microorganisms is not very strong or stable over a short time, and that termite gut microbial community structures vary depending on components of the feeds.     

Harvesting rate of the termite,Drepanotermes tamminensis (Hill) within native woodland and shrubland of the Western Australian wheatbelt

The Western Australian termite,Drepanotermes tamminensis (Hill), harvests various plant materials according to biomass availability. The main litter components harvested by this termite in a woodland dominated byEucalyptus capillosa are bark and leaves of the major tree species, while in shrubland dominated byAllocasuarina campestris, shoots of this species are taken. Harvesting mainly occurs during the autumn (April–May) and spring (September–October) seasons. The commencement and duration of harvesting appears to depend partly on weather conditions, with harvesting taking place at temperatures between 15 and 25°C after periods of rain. This species of termite harvests approximately 15.6 g m⁻² year⁻¹ and 3.2 g m² year⁻¹ (dry weight of plant material) in the woodland and shrubland, respectively.     

Effects of virulence,sporulation, and temperature on Metarhizium anisopliae and Beauveria bassiana laboratory transmission in Coptotermes formosanus

Sporulation characteristics and virulence of Metarhizium anisopliae and Beauveria bassiana were examined in relation to laboratory transmission in Coptotermes formosanus. Fungal isolates significantly affected disease prevalence in termite populations. Sporulation of M. anisopliae played a more important role than virulence in producing epizootics within small groups of termites, but this was not the case for B. bassiana. Isolates characterized by quick sporulation (day 2 after death) did not exhibit better transmission in termites than those with high total sporulation (day 11 after death) in either fungal species. An isolate of M. anisopliae ranking highly in all three categories (virulence, quick sporulation, and total sporulation) produced better epizootics than an isolate that was inferior in all three characteristics. High temperatures (35 degrees C) significantly reduced fungal germination rates, leading to significant reduction of epizootics. M. anisopliae was better than B. bassiana in producing epizootics at 27 degrees C. Thus, fungal characteristics other than virulence should be considered for the seasonal colonization approach to termite microbial control.     

Morphology and Molecular Phylogeny of Staurojoenina mulleri sp. nov. (Trichonymphida,Parabasalia) from the Hindgut of the Kalotermitid Neotermes jouteli

Staurojoenina is a large and structurally complex genus of hypermastigont parabasalians found in the hindgut of lower termites. Although several species of Staurojoenina have been described worldwide, all Staurojoenina observed to date in different species of North American termites have been treated as the same species, S. assimilis. Here, we characterize Staurojoenina from the North American termite Neotermes jouteli using light microscopy, scanning electron microscopy, and phylogenetic analysis of small subunit ribosomal RNA, and compare it with S. assimilis from its type host, Incisitermes minor. The basic morphological characteristics of the N. jouteli symbiont, including its abundant bacterial epibionts, are similar as far as they may be compared with existing data from S. assimilis, although not consistently identical. In contrast, we find that they are extremely distantly related at the molecular level, sharing a pairwise similarity of SSU rRNA genes comparable to that seen between different genera or even families of other parabasalians. Based on their evolutionary distance and habitat in different termite genera, we consider the N. jouteli Staurojoenina to be distinct from S. assimilis, and describe a new species, Staurojoenina mulleri, in honor of the pioneering parabasalian researcher, Miklos Muller.     

Invertebrate bioturbation can reduce the clogging of sediment: an experimental study using infiltration sediment columns

1. Invertebrate bioturbation can strongly affect water‐sediment exchanges in aquatic ecosystems. The objective of this study was to quantify the influence of invertebrates on the physical characteristics of an infiltration system clogged with fine sediment. 2. Two taxa (chironomids and tubificids) with different bioturbation activities were studied in experimental slow infiltration columns filled with sand and gravel and clogged with a 2 cm layer of fine sediment at the surface. We measured the effects of each taxon separately and combined on hydraulic head, water mobility and sediment reworking. 3. The results showed that invertebrates could reduce sediment clogging and this effect was linked to the functional mode of bioturbation of each group. Tubificid worms dug networks of galleries in the fine sediment, creating pathways for water flow, which reduced the clogging of sediment. In contrast, the U‐shaped tubes of chironomids were restricted to the superficial layer of fine sediments and did not modify the hydraulic conductivity of experimental columns. The combination of invertebrates did not show any interactive effects between tubificids and chironomids. The occurrence of 80 tubificids in the combination was enough to maintain the same hydraulic conductivity that 160 worms did in monospecific treatment. 4. The invertebrates like tubificid worms can have a great benefit on functioning of clogged interfaces by maintaining high hydraulic conductivity, which contributes to increased water‐sediment exchanges and stimulates biogeochemical and microbial processes occurring in river sediments.