Electrical Performance and Effect of Frequency Electromagnetic Waves on Subterranean Termites <i>Coptotermes curvignathus</i>Holmgren

The research aimed to propose a non-destructive technology to control subterranean termites Coptotermes curvignathus Holmgren infestation based on electromagnetic waves. A portable apparatus for this technology has been built and its experiment is presented in this paper. Some electrical parameters were measured and analyzed along with their effects to the termites. The experiment using frequency range between 30 Hz - 600 kHz has been done. The average error of the apparatus by comparing the result with the direct measurement using oscilloscope was also measured. The highest error value appeared at 600 kHz with frequency error 6.05 kHz. The highest error of voltage (i.e. 0.186 Volt) appeared at 100 kHz. For safetiness, the highest magnetic field at 300 kHz was 0.1815 μT and at 500 kHz was 0.00725 μT which were safe for human. The average value of termites mortality was higher on irradiation time 120 minutes than 60 minutes respectively in all test frequency: 300 kHz, 400 kHz, 500 kHz and 600 kHz. This paper presents an important information of the electromagnatic-based technology for environmental friendly termites control in spite of using the insecticides.

Bacterial microbiome of Coptotermes curvignathus （Isoptera： Rhinotermitidae） reflects the coevolution of species and dietary pattern

Coptotermes curvignathus Holmgren is capable of feeding on living trees. This ability is attributed to their effective digestive system that is furnished by the termite＇s own cellulolytic enzymes and cooperative enzymes produced by their gut microbes. In this study, the identity of an array of diverse microbes residing in the gut of C. curvignathus was revealed by sequencing the near-full-length 16S rRNA genes. A total of 154 bacterial phylotypes were found. The Bacteroidetes was the most abundant phylum and accounted for about 65% of the gut microbial profile. This is followed by Firmicutes, Actinobacteria, Spirochetes, Proteobacteria, TM7, Deferribacteres, Planctomycetes, Ferrucomicrobia, and Termite Group 1. Based on the phylogenetic study, this symbiosis can be a result of long coevolution of gut enterotypes with the phylogenic distribution, strong selection pressure in the gut, and other speculative pressures that determine bacterial biome to follow. The phylogenetic distribution of cloned rRNA genes in the bacterial domain that was considerably different from other termite reflects the strong selection pressures in the gut where a proportional composition of gut microbiome of C. curvignathus has established. The selection pressures could be linked to the unique diet preference of C. curvignathus that profoundly feeds on living trees. The delicate gut microbiome composition may provide available nutrients to the host as well as potential protection against opportunistic pathogen.

Exploring the region-wise diversity and functions of symbiotic bacteria in the gut system of wood-feeding termite,Coptotermes formosanus,toward the degradation of cellulose,hemicellulose,and organic dyes

The wood-feeding termite Coptotermes formosanus represents a unique and impressive system for lignocellulose degradation.The highly efficient digestion of lignocellulose is achieved through symbiosis with gut symbionts like bacteria.Despite extensive research during the last three decades,diversity of bacterial symbionts residing in individual gut regions of the termite and their associated functions is still lacking.To this end,cellulose,xylan,and dye-decolorization bacteria residing in foregut,midgut,and hindgut regions of C.formosanus were enlisted by using enrichment and culture-dependent molecular methods.A total of 87 bacterial strains were successfully isolated from different gut regions of C.formosanus which belonged to 27 different species of 10 genera,majorly affiliated with Proteobacteria(80%)and Firmicutes(18.3%).Among the gut regions,37.9%of the total bacterial isolates were observed in the hindgut that demonstrated predominance of cellulolytic bacteria(47.6%).The majority of the xylanolytic and dye-decolorization bacteria(50%)were obtained from the foregut and midgut,respectively.Actinobacteria represented by Dietza sp.was observed in the hindgut only.Based on species richness,the highest diversity was observed in midgut and hindgut regions each of which harbored seven unique bacterial species.The members of Enterobacter,Klebsiella,and Pseudomonas were common among the gut regions.The lignocellulolytic activities of the selected potential bacteria signpost their assistance to the host for lignocellulose digestion.The overall results indicate that C.formosanus harbors diverse communities of lignocellulolytic bacteria in different regions of the gut system.These observations will significantly advance our understanding of the termite–bacteria symbiosis and their microbial ecology uniquely existed in different gut regions of C.formosanus,which may further shed a light on its potential values at termite-modeled biotechnology.

Evaluation of the toxicity and repellency of tropical plant extract against subterranean termites,Globitermes sulphureus and Coptotermes gestroi

The harmful effects of chemical-based termiticides and the increased incidence of termite resistance have resulted in the need for safer and more effective termiticides.Therefore,the screening of antitermiticidal activity of naturally-occurring products could possibly hamper an alternative means in termite control strategies.The aims of this study were to determine the toxicity and repellency of L.leucocephala,A.paniculata,Az.indica and P.niruri crude extracts against two subterranean termites,G.sulphureus and C.gestroi.Bioassays were conducted by applying varying concentrations of the plant extracts(10,000 ppm,5000 ppm and 500 ppm)on both termite species under laboratory conditions.All extracts exhibited a significant antitermiticidal activity in time-and concentration-dependent manners after 14 days of exposure.The highest mortality of G.sulpureus and C.gestroi were noted in all methanolic extracts of P.niruri,L.leucocephala,A.paniculata,Az.indica at 10,000 ppm.High repellent activity was also noted in the choice bioassay when both termites were treated with all methanolic extracts at 10,000 ppm.

Evaluation of Tung Oil(Vernicia fordii(Hemsl.))for Controlling Termites

In worldwide,the use of chemical pesticides to protect wood has been greatly restricted.In recent years,a large number of researchers devoted to the search for natural,safe and non-polluting bioactive chemical compounds from plants as an alternative to synthetic organic chemical preservative.In Chinese folk,tung oil can be used as paint for wooden furniture to protect them from pests.This study aimed to evaluate the chemical compositions of raw and heated tung oil and their activity against termite.In choice bioassays,weight loss of wood treated with 5%raw or heated tung oil after 4 weeks was significantly less than that of the control group.In no-choice bioassays,there was a significant difference in termite survival and wood weight loss on raw and heated tung oil-treated wood.When tung oil-treatment concentrations increased to 5%,wood weight loss was less than 10%.There was no significant difference in termite survival and wood weight loss between raw and heated tung oil-treated wood.Survival of termites in both tung oil wood treatments was significantly lower than that in the starvation control after 4 weeks.Raw and heated tung oil significantly improved the resistance of pine wood to termites,and have the potential for the development of natural wood preservatives.

八种乳白蚁兵蚁的形态学研究

为了明确乳白蚁(Coptotermes spp.)形态分类中一些特征的分类价值,采用显微测量、显微观察及电镜扫描技术,对国内采集和口岸截获的8种乳白蚁兵蚁的形态进行了研究.结果显示,乳白蚁兵蚁囟孔侧毛数、头区刚毛数、头型、触角节数、上颚弯曲度、前胸背板刚毛数和前胸背板侧缘形状等7个特征可作为区分乳白蚁兵蚁的有效特征,并根据这些特征列出了8种乳白蚁的形态分类检索表.

Subterranean termites （Isoptera： Rhinotermitidae）： Exploitation of equivalent food resources with different forms of placement

Coptotermes gestroi and Heterotermes tenuis have been described as important urban pests in Brazil. The establishment of control technologies using baits that consider the social behavior of termites requires a better knowledge of their foraging behavior. Thus, this study analyzed the feeding behavior of these species with three different forms of food placement： food on the surface of a substrate and food either partially or completely buried in the substrate. Experimental arenas were composed of a central chamber connected to three food chambers. Each central chamber contained 550 foragers of C. gestroi or 517 foragers of 11. tenuis. Blocks of Pinus elliottii were placed in the different food chambers. After 28 days, the consumption of each wood block and the percentage of foraging individuals recruited for food chambers were verified in relation to the total survival rate obtained for each one of the 20 replicates. Results showed that completely buried food was most consumed for H. tenuis and presented a higher recruitment rate of workers and soldiers for both species. Although the consumption had non-significant differences for C. gestroi, these termites exhibited a tendency to prefer completely buried food. In these conditions, it can be concluded that the forms of food placement used in the present research influenced the recruitment of individuals for both species. Data also suggests that when the foraging subterranean termites find food resources in the tunneling substrate, they tend to concentrate their efforts on it, a behavior regime that reduces exposure to external environment.