Void Content Analysis of a Polymer Composite Manufactured via Resin Infusion Process

Void formation in composite has a strong influence on mechanical properties. In vacuum infusion process, void may form due to the variations in permeability on a filament and filament bundle scale, outgassing of dissolved gas in the resin, evaporation of volatile components in the resin, shrinkage of the resin and leakage in connections and mould. Voids can be reduced by controlling manufacturing parameters such as vacuum pressure, cure temperature, autoclave pressure, and resin viscosity. The inclusion of voids in the final part will have a detrimental impact on the mechanical properties of the composites even at a very low volume fraction

Metarhizium anisopliae of Peninsular Malaysia origin poses high pathogenicity toward Coptotermes curvignathus, a major wood and tree pest

The termite Coptotermes curvignathus has been reported in Malaysia and is responsible for the destruction of various timber-based products and orchard trees. Controlling this pest population using the biopesticide agent, Metarhizium anisopliae, is highly desirable when compared to chemical pesticides because the latter often leads to many environmental concerns. In this study, we isolated M. anisopliae from four different locations in Peninsular Malaysia and tested their pathogenicity on C. curvignathus. Another six isolates from a previous work were also included. Conidia in the form of suspension at 1x107 conidia/mL were applied on workers termites and observed for mortality within a 12-day observation period. In addition, fungal progression rate was calculated based on the number of days it took for the mycelia to emerge and the conidia to form on infected termites. Among the ten fungal isolates tested, PR1 yielded the highest mortality (97%) and the shortest median lethal time (LT50= 1.5 days). While TFFH3 and PKLG isolates had the highest rate in mycelia formation (88%) and conidia sporulation (80%), respectively, they both recorded mortality at 93% and LT50 above 2 days. PR1’s performance in infecting C. curvignathus appeared to augment its potential use as a biopesticide agent

Differentially expressed wound-response-related proteins from a major agarwood-producing tree, Aquilaria malaccensis Lam. identified via 2-D electrophoresis

The urban transit routing problem (UTRP) deals with public transport systems in determining a set of efficient transit routes on existing road networks to meet transit demands. The UTRP is a complex combinatorial optimization problem characterized with a large search space, multi-constraint, and multiobjective nature where the likelihood of generating infeasible route sets is high. In this paper, an improved sub-route reversal repair mechanism is proposed to deal with the infeasibility. A population-based metaheuristic, namely, Differential Evolution (DE) algorithm is then proposed to handle the multiobjective UTRP with the aim of devising an efficient transit route network that optimizes both passengers' and operators' costs. Computational experiments are performed on well-known benchmark instances to evaluate the effectiveness of the proposed repair mechanism and the DE algorithm. The computational results are reported to have better parameter values in most cases when compared to other approaches in the literature

Damaging insect pests and diseases and their threats to agarwood tree plantations

The cultivation of agarwood tree species such as Aquilaria has grown dramatically during the last ten years. This development is driven by the desire to produce sustainable agarwood to meet the high market demand. In the past, the main source of agarwood had been from natural forests, which resources are now declining. Although there are various examples of pests and diseases affecting early plantations, these damages were often overlooked. Recently, the emergence of new pests and diseases in large-scale Aquilaria tree plantations has raised concerns among planters and researchers, as the damage level to the trees may vary from unsubstantial to tree mortality. Lack of information on the types of pests and diseases in Aquilaria plantations makes it difficult to properly manage these threats, leading to economic losses. This review summarizes the insect pests and diseases known to damage cultivated agarwood trees in various countries including China, India, Indonesia, and Malaysia. As we learn from the cultivation practices of other monoculture crops, these insect pests and pathogens are a major challenge to the healthy growth of agarwood trees. The implementation of an integrated pest and disease management at an early stage of plantation establishment may hold the key to help control and contain these threats from turning into major outbreaks

First record of basal stem rot of foxtail palm Wodyetia bifurcata caused by Ganoderma boninense in Malaysia

Wodyetia bifurcata Irvine, commonly known as the foxtail palm, is a graceful palm species that has caught the interest of horticulturists and landscape architects due to the uniqueness of its foliage, fast growth, and lack of significant plant pests. In January 2016, a disease inspection carried out at the Royal Selangor Golf Club, Kuala Lumpur, found four foxtail palm trees infected by basal stem rot (BSR). In the field, the trees were observed to show pale green, wilted leaflets and collapsed fronds with only a single spear leaf remaining. At the base of infected trees, the presence of white fungal primorida, depression in outer bark, and necrotic symptoms were visible on basal stem bark. Dead tissues underneath the outer bark were obvious; the tissues were brown, rotten, and moist with the presence of white mottling mycelia. However, healthy tissues were found to be firm and cream in color. Rotten stem of the affected palm emitted a mushroom-like odor, brownish, dry, and friable, especially at the center. Diseased stems of a foxtail palm were cut and brought to Forest Research Institute Malaysia (FRIM) for isolation and identification of associated fungus. The fungus recovered from the diseased palm was identified as Ganoderma boninense. Macroscopic and microscopic observations revealed that pure culture of the fungus was white, dense, and felty to floccose. The generative hyphae were hyaline, septate, and thin-walled with clamps, whereas the binding hyphae were branched, thick-walled, without septation, and hyaline. Cuticular cells were spherical to irregular in shape, thick-walled, encrusted, and golden brown in color. Fruiting bodies of the fungus were tough and dimidiate form with light to dark brown, undulating, and laccate upper surface. Spores were ellipsoid measuring 11.84 to 13.82 × 7.72 to 9.72 µm, truncated, golden brown, and thick-walled with a rough surface. The identified fungus was allocated with reference number FRIM690. A pathogenicity test was carried out on seven healthy and uniform 2-year-old foxtail palm saplings obtained from a local nursery at Sg. Buluh, Selangor, according to the technique described in a previous study (Mohd Farid et al. 2005). Of these, two saplings were used for control. Prior to inoculation, the blocks were inoculated with G. boninense agar plugs. Control blocks were inoculated with sterilized PDA plugs. The test revealed that early symptoms of the disease infection were often yellowing, wilt, and drying of pinnae. It was then followed by collapse of fronds after all the pinnae had dried up. Finally, there was only a single shrunken spear left. In general, all the symptoms were visible between 16 and 40 weeks after inoculation. At the end of the experiment, all harvested symptomatic saplings brought to the laboratory successfully recovered G. boninense. For molecular identification, PCR amplification was carried out for the ribosomal DNA internal transcribed spacer (ITS) region with primers ITS1 and ITS4 (White et al. 1990). The amplicon was cloned, sequenced, and deposited in GenBank (accession no. KY352306). BLAST search showed 99% identity to G. boninense (KX092000; KF164430; AB985729). In conclusion, both morphological and molecular characteristics supported the identification as G. boninense Pat. To our knowledge, this is the first record of G. boninense causing BSR on foxtail palm trees. This disease threatens tree survival, and may potentially negatively affect landscape in urban areas

Interaction between an entomopathogenic fungus Metarhizium anisopliae and its host subterranean termites Coptotermes curvignathus during infection process

The subterranean termites, Coptotermes curvignathus is a destructive pest of tree plantation in Malaysia. Controlling termite population by chemical is not a good option since it may increase the resistance of pest towards the pesticide and cause several implications towards biodiversity and environment. Metarhizium anisopliae, an entomopathogenic fungus is a good option by controlling the termite biologically. In this study, ten M. anisopliae isolates were screened for their pathogenic effect on termites. The best isolate, PR1 which originated from Pantai Remis, Selangor is the most prudently isolates by yielded the highest mortality (96.97%) and the shortest median lethal time (LT50= 1.47 days). This isolate was utilized in downstream study by conducting the histopathology and protein expression study; for each stages of pathogenesis up to 144 h of post-inoculation. Results demonstrated that it requires two days to kill infected host starting by germ tube penetration through the termite cuticle observed at 6 h postinoculation. Injury caused by M. anisopliae’s appressorium in a way to penetrate the first layer of host defense mechanism, the cuticle, one of the factors that weakening the infected host. Dissemination and of fungal and hyphal bodies observed on cellular level is a proof that M. anisopliae invaded the host starting from the cellular level. Then, inoculated termites were mummified and the sporulation of M. anisopliae on host’s carcasses observed at 96 h and 144 h of post-inoculation, respectively. Meanwhile in protein expression study, four and five significance expressed proteins have been identified from C. curvignathus and M. anisopliae, respectively. Expressed proteins in termite shows evidence that being involve in cell regulation and immune response towards infection by this entomopathogenic fungus. Meanwhile, the expressed proteins extracted from M. anisopliae were discovered to be involved in the protein transportation and also related with fungus virulencity during infection process. By knowing the interaction between this host-pathogen relationship, the achieved knowledge could be utilized in future development of biopesticide by using this fungus to control termite population effectively

Mining and analysis of chloroplast simple sequence repeats SSRs from eight species of Aquilaria

Aquilaria is a tropical forest tree, producer of the famed and expensive agarwood. Aggressive collection of agarwood put strain on the natural stands of Aquilaria species, sparking efforts to domesticate the tree and cultivate agarwood in plantations. However, tree domestication progress is hampered by the scarcity of genomic resources that is crucial for breeding programs. In this study, the complete chloroplast (cp) genome sequences from eight Aquilaria species were analyzed in silico. For identification of the simple sequence repeats (SSRs), MISA PERL script which had a repeat length of 12 for mononucleotides (mono-), 6 for dinucleotides (di-), 4 for trinucleotides (tri-), 3 for tetranucleotides (tetra-), pentanucleotides (penta-), and hexanucleotides (hexa-), respectively, along with frequency were utilized. From a total of 312 SSRs that were discovered, merely 50 (16%) were found localized within the coding region while the majority (84%) were within the intergenic regions, with an average of one SSR per 4.5 kb. The mean length of the SSRs were 11.63 bp. Mono- repeats were the predominant motifs (29.2%), followed by tetra- (28.8%), di- (20.5%), tri- (19.9%), and penta- (1.6%). Whereas the most recurring motifs were A/T (97.8%) for mono-, AT/AT (87.5%) for di-, AAT/ATT (48.4%) for tri-, and AAAT/ATTT (45.6%) for tetra-. GO analysis using the REVIGO software identified four molecular functions, six biological processes and three cellular components. In conclusion, findings of this study offer a scientific foundation for future phylogenetics, evolutionary genetics, diversity studies and breeding programs on Aquilaria species

Soil-borne entomopathogenic bacteria and fungi

Being rich in microorganisms, the soil is an ideal environment and important reservoir for harvesting various types of beneficial microorganisms. Soil-borne entomopathogenic bacteria and fungi have been regularly isolated around the world to support crop producer in the never-ending arms race of pest management. Among these microorganisms, entomopathogenic bacteria and their toxins are the most successful microbial insecticides also from the commercial point of view. They grouped into spore- and non-spore-forming entomopathogens, in which the infection process starts upon ingestion by the susceptible insect hosts. Fungi, on the other hand, remain relatively underutilized as natural enemies despite their many advantages over other biological and chemical products. They mainly classified under the class of Entomophthoromycetes and Sordariomycetes in the larger Ascomycota division, which consists around 65,000 described species. In comparison to bacteria, fungi have a wider host range and are especially suitable for controlling pests with piercing and sucking mouthparts. Entomopathogenic bacteria and fungi can be released through inundative application methods and therefore play a critical role in integrated pest management (IPM) against several pests. This chapter provides a selective review on the different types of soil-borne entomopathogenic bacteria and fungi, including their distribution, infection mechanisms and host ranges

Evaluation of the virulence of entomopathogenic fungus, Isaria fumosorosea isolates against subterranean termites Coptotermes spp. (Isoptera: Rhinotermitidae)

The entomopathogenic fungus Isaria fumosorosea Wize, formerly known as Paecilomyces fumosoroseus is reported as a promising biocontrol agent for controlling subterranean termites, particularly those belonging to the family Rhinotermitidae. In Malaysia, the family Rhinotermitidae includes two species of subterranean termites with extremely high economic importance; namely Coptotermes curvignathus Holmgren, and the Asian Subterranean Termite (Coptotermes gestroi Wasmann). To comprehend the potential control of this soil-dwelling fungus against these subterranean termites in Malaysia, an investigation was carried out by testing the pathogenecity of 11 isolates against these termite species. All isolates showed pathogenic potential against the termite (Mortality rate of C. curvignathus: 84.4%; C. gestroi: 67.3%). Isolate PF49 was the most effective against both species of termites and was further tested for its virulence and mycosis. The LC50 values of PF49 against C. curvignathus and C. gestroi were 7.55 × 103 and 1.09 × 102 conidia/ml, respectively. The average number of days required to complete the mycosis process in C. curvignathus and C. gestroi were 4.7 and 8 days, respectively. These fungi are believed useful for protecting living trees, plants, wood, wood structures, and other cellulosic materials susceptible to termite infestation and damage

Survey, identification, and pathogenicity of Ceratocystis fimbriata complex associated with wilt disease on Acacia mangium in Malaysia

Ceratocystis wilt disease surveys were conducted in three selected Malaysian Acacia mangium plantations. These completed surveys revealed the occurrence of the wilt disease, with the incidence of infection ranging from 7.5% to 13.6%. Signs of wood-boring insects, bark peeling due to squirrel activity, and pruning wounds were often associated with this disease. The fungus most frequently isolated from the diseased trees was the Ceratocystis fungus. The analysis on the morphological characteristics has identified the fungus as Ceratocystis fimbriata complex. Phylogenetic analysis based on the sequences of the ITS, and concatenated sequences of EF1α-βT regions grouped the isolates within the C. fimbriata sensu stricto, in comparison to other C. fimbriata isolates. Pathogenicity tests were conducted on six to nine-month-old healthy A. mangium seedlings by inoculating these seedlings with eight out of the 16 isolates. The results demonstrated that all the isolates were pathogenic, with mortality beginning as early as two weeks after inoculation. However, an ANOVA test indicated a significant difference between the pathogenicity levels among the fungal isolates. The results also showed that pathogen aggressiveness was not correlated with geographical origin. A host range test was also conducted by using C. fimbriata SSB3 and FRIM1162 isolates against several forest plantation species. The findings suggested that only A. mangium was susceptible to C. fimbriata. The other species remained healthy with no symptoms of infection even after seven weeks of treatment, as compared to the A. mangium species, where between 38 to 60% of the inoculated plants had died. This study provides new information on the status of Ceratocystis wilt disease, especially on the occurrence and effects on A. mangium plantation, by giving insights on how to control and manage this ferocious plant pathogen in the future