From an evolutionary perspective, it is speculated that termites have evolved to construct tunnels in a manner that optimizes search and transport efficiency. While numerous studies have focused on search efficiency, there has been limited research on transport efficiency due to the challenges associated with direct field observations. To address this challenge, we developed an individual-based model to simulate the transport process. Using the model, we examine the effects of several key variables on transport efficiency, Based on our results, we discuss potential strategies that termites might employ to optimize transport efficiency. In addition, we briefly discuss ways to improve the realism of the model.

최근 국내에서 외래 곤충인 (가칭)마른나무흰개미(Cryptotermes domesticus)가 서울에 위치한 주택에서 발견되었다. 이 종은 국내에 정착할 경우 잠재적으로 목재나 목조건물에 피해를 줄 수 있어 시급한 국내 발생 조사가 필요하다. 본 연구에서는 종 분포 모델 기법을 활용하여 마른나 무흰개미의 정착 가능성과 관련된 기후적합성을 추정하는 것을 목표로 하였다. 문헌 자료를 바탕으로 전세계 분포 정보를 수집하고, 생물기후변 수를 활용하여 4개의 모델링 알고리즘으로 기후적합성 예측 모델을 구동하였다. 개발한 모델들의 결과를 종합하여 최종적으로 마른나무흰개미 의 평균 발생 확률로 표현되는 앙상블 모델을 개발하였다. 그 결과 마른나무흰개미는 열대 지방에서에서 해양성 기후를 보이는 연안이나 도서지 역에서 기후적합성이 높을 것으로 예상되었다. 국내에서는 기후적합성이 전반적으로 낮을 것으로 추정되었다. 하지만, 마른나무흰개미의 정착 및 확산 가능성을 염두해두고, 최근 발생이 보고된 지점을 중심으로 정밀 역학 조사가 필요할 것으로 보인다.

In this study we present a new approach to estimating termite populations size. So far, termite researchers have been using the mark-capture-recapture method. This method has a disadvantage that measurement time is long and error range is large. To this end, we built an agent-based model to simulate termite tunneling behavior. Using this model, we made simulated tunnel patterns that are determined by three variables: the number of simulated termites (N), the passing probability of two encountering termites (P), and the distance that termites move soil parcels (D). To explore whether the N value can be estimated with a partial termite tunnel pattern, we generated four groups of tunnel patterns that are partially obscured in complete tunnel pattern image: (1) A pattern group in which the outer area of the tunnel pattern is obscured (I-pattern), (2) a pattern group in which half of the tunnel pattern is obscured (H-pattern), (3) a pattern group in which the inner region of the tunnel pattern is obscured (O-pattern), and (4) a pattern group combining I- and O-pattern (IO-pattern). For each group, 80% of the tunnel patterns were learned through a convolution neural network (CNN) and the remaining 20% of the patterns were used for estimating N value. The estimation results showed that the N estimates for the IO-pattern are the most accurate and are in the order I-, H-, and O-patterns. This means that the termite population size can be estimated based on tunnel information near the center of the colony.

We have determined the mitochondrial genome of Reticulitermes speratus kyushuensis Morimoto, 1968. The total length of the R. speratus kyushuensis is 15,898 bp with 65.3% A + T content. It consists of 13 protein–coding, 22 tRNA, 2 rRNA genes and an A+T–rich control region. All the protein–coding genes used ATN as start codon. But the stop codons were TAA, TAG, and an incomplete termination codon (T) abutting an adjacent tRNA gene. The A+T–rich control region was 1,105 bp in length with 67.8% A + T content

Swarming alates of termite Macrotermes sp. has been accepted as food among people of Benishangul Gumuz zone in west Ethiopia bordering with Sudan. The preference seems to be for the reproductive caste. We assessed the nutritional composition of nymph and alate of Macrotermes sp. of Ethiopia. The adult contained higher amino acids (31%) compared to nymph (21%). However, the distribution of amino acids in the protein was similar (ap. 4:6 essential to non-essential amino acids). Both stages tend to have high fat contents (50%). Fat supplement could be a possible reason behind the human consumption of termites. Beside the bio-prospection of termite as food or oil source, termite foraging would have important evolutionary biology due to their significant amount of energy-yielding nutrients which could presumably be critical resource for development of larger brained hominines.

The aim of this study is to analyze the functional activity of an endo-β-1, 4-glucanase from the wood dwelling lower termite Coptotermes gestroi. Full length cDNA sequences of the endo-β-1,4-glucanase were obtained by primer walking in conjunction with Rapid Amplification cDNA Ends. With the obtained full length sequences, primers for amplifying open reading frame (ORF) excluding the signal peptide and glycophosphatidylinositol anchor were designed. Amplified endo-β-1,4-glucanase fragment was cloned and expressed using pET30(+) expression vector in BL21 E.coli strain. Expression of endo-β-1,4-glucanase was confirmed by Western blotting and the result revealed that only full ORF was expressed. The cellulase activity of protein preparations from the induced and non-induced cells was analyzed with Congo Red assay with the cellulase from Aspergillus niger (Sigma Aldrich) as a positive control. The activity of C. gestroi endo-β-1,4-glucanase was significantly higher than those observed in the positive control and the enzyme preparation from non-induced cells. Therefore, this study confirmed that C. gestroi endo-β-1,4-glucanase had a function of cellulose hydrolysis.

The Japanese termite, Reticulitermes speratus Kolbe, is distributed in Korea widely. Although, termites are not currently a great problem in Korea, it might be increased commercial losses from imported timber. Phosphine (PH3) is very effective fumigant and is widely used to control pests. Oxygen treatment was found to enhance phosphine toxicity and reduce fumigation time against various life stage of insects. In this study, we determined efficacy of oxygenated phosphine fumigation for controlling R. speratus. Fumigation to adults of R. speratus was carried in a desiccator system at 20.9% (normal), 50% and 80% of oxygen concentration for 24 h. Fumigations under higher oxygen levels greatly increased phosphine toxicity to R. speratus. Mortality of termite was increased 15.0% and 16.2% in the 50.0% and 80.0% oxygen concentration with 0.25 mg L-1 phosphine at 5℃, respectively. 100% mortality was determined in 80.0% oxygen concentration with 0.5 mg L-1 phosphine at 5℃. Oxygenated phosphine fumigations have marked potential to improve insecticidal efficacy against R. speratus. These results merit further study as potential fumigant for control of wood destroying pests.

To search for a variety of cellulase genes from termites with different habitats consuming different foods, we collected three species (Neotermes spp., Odontotermes spp., Macrotermes spp.) from the wood and one species (Nasutitermes spp.) from the cow dung. Total RNA was isolated both from alimentary track tissues containing paunch and from other tissues, and used for the suppression subtractive hybridization (SSH). The resulting EST libraries were sequenced and searched by BLAST to identify cellulase genes. A total of 16 cellulase genes were found from the wood-dwelling termites whereas 4 cellulase genes from the cow dung-dwelling termites. Endo-beta-1,4-glucanase and beta-glucosidase were identified as the most abundant cellulase from the wood-dwelling termites and cow dung-dwelling termites, respectively. This finding suggests that cellulase profiles are significantly different depending on the termite’s habitat and food. In addition, we analyzed phylogenetic relationships among the cellulase genes along with other cellulase genes reported to date. All cellulase genes appeared to be originated from endosymbioants without any hint of horizontal gene transfer. Functional expression of endo-beta-1,4-glucanase using a baculovirus expression system is in progress to characterize its enzymatic properties.

Termites are a major problem for home and business owners around the world. Termites gnaw through wood and burrow under the foundations of buildings causing a great deal of damage to the structure of the building. Phosphine (PH3) is very effective fumigant and is widely used to control pests. PH3 rapidly penetrate through treated material, so it replaced many conventional fumigants for treatment of durable materials. In this study, we have investigated the effectiveness of PH3 fumigation on wood pests, Reticulitermes speratus kyushuensis. We evaluated two bioassay methods; wooden cube (10×10×10 cm) and insect breeding dish in comparison with effectiveness of PH3 penetrations into the timber block. Fumigation to adults of R. speratus was carried in a desiccator system for 24 h at 5 and 15℃. As a result, LC99 of PH3 to R. speratus in wooden cubes and insect breeding dish at 5℃ was 0.183 and 0.177 mg L-1, respectively. LC99 of PH3 in wooden cubes and insect breeding dish at 15℃ was 0.077 and 0.078 mg L-1, respectively. There were no significant differences between the two bioassay methods. Thess results indicate that PH3 described herein merit further study as potential fumigants for termite control.

Plant essential oils from 26 plant species were tested for their insecticidal activities against the Japanese termite, Reticulitermes speratus Kolbe, using a fumigation bioassay. Responses varied with source, exposure time, and concentration. Among the essential oils tested, strong insecticidal activity was observed with the essential oils of ajowan (Trachyspermum ammi), allspice (Pimenta dioica), caraway (Carum carvi), dill (Anethum graveolens), geranium (Pelargonium graveolens), and litsea (Litsea cubeba). The composition of six essential oils was identified by using gas chromatography-mass spectrometry. The compounds thus identified were tested individually for their insecticidal activities against Japanese termites. Responses varied in a dose-dependent manner for each compound. Phenol compounds exhibited the strongest insecticidal activity among the test compounds further, alcohol and aldehyde groups were more toxic than hydrocarbons. The essential oils and compounds described herein merit further study as potential fumigants for termite control.

Subterranean termiteslive in the soil and wood that is in contact with soil. They have to discover food by constructing underground tunnel networks. Once the food is discovered and connected to the galleries, one important aspect of the foraging behavior is the food transfer by individual termites moving within the existing tunnels that lead to multiple existing food sources. In order to reveal how much the tunnel network is reliable to the food transfer efficiency, we used a lattice model suggested by Lee et al. (2006), which is capable of simulating the tunnel networks of Coptotermes formosanus and Riparius flavipes. After constructing the simulated tunnel networks, we randomly distributed food particles on the tunnel networks and then computed path entropy for the networksby selecting and evaluating the shortest paths from encountered food particles to the nest. The path entropy measured the degree of reliability of the networks for the food transfer entropy. Simulation results showed that path entropy between the simulated networks of C. formosanus and R. flavipes was significantly different due to the combinational effects of the network components such as the number of primary tunnels and the branching probability. We discussed the meaning of the results in relation to termite foraging efficiency.

Subterranean termites excavate tunnels for searching and transporting food below the ground, which in turn causes complicated tunnel networks. In the present study, we explored the connectedness of the networks by using spectral graph theory. In the theory, tunnel network pattern can be constitutively expressed by the Laplacian matrix, and among the set of all eigenvalues of the matrix, the second eigenvalue directly reflects the degree of the connectedness. We constructed the simulated tunnel networks for Coptotermes formosanus and Riparius flavipes by the use of a lattice model suggested by Lee et al., (2006) and computed their connectedness. The results showed that the values of the connectedness between the two species were statistically-significantly different. We briefly discussed the results in relation to foraging efficiency.