Vol. 19 No. 5 (2021)

Callosobruchus maculatusFabricius is one of the most economically important beetles  infesting  many grains during storage. Understanding of the life cycle of C. maculatusthat was necessary to use for pest management. A study on the biological and ecological characteristics of C. maculatuswas done in the laboratory at the Department of Entomology, Vietnam National University of Agriculture. The effect of temperature on bruchid development was also observed by the individual methodology. It was found that the life cycle of C. maculatuswas 29.07; 26.83 and 23.64 days at 25; 27.8 and 30C, respectively. The longevities of females and males were decreased as temperatures increased. The means number of eggs laid per female at 25; 28.2 and 30C were 48.93, 54.26 and 64.73 eggs/female, respectively. The highest mean number of egg laid was found within the first 3 days. C. maculatuspreferred to lay egg on white seed beans. The larval densities (1, 2, 3, 4 larvae/seed) significantly reduced the seed weight (the weight loss 3.97; 10.65; 15.35 and 19.36 mg respectively). The adult emergence percentage decreased inversely proportional to the density of larvae per bean seeds. Increasing larval density caused reducing the germination rate of bean seeds.

Hedychium(ginger-lily)genus, belongs to Zingiberaceae familyand is not only known as medicinal plants but also ornamental materials. Our study focused on evaluating the characteristics of growth, development, and flower quality of five ginger-lily accessions, collected in some Northern provinces of Vietnam and planted in Gia Lam, Hanoi for ornamental purposes. The experiment was arranged in blocks of non-repeating sequence, each accession being as one block. The results showed that five ginger-lily accessions grew all-year-round, lacked the withering stage, flowered from July to November, had the height of plants from 90.5 to 168.8 cm, with slight pest damage. The flowers of all accessions were fragrance with the milky white perianth, except the NT3 had bright yellow perianth. Five ginger-lily accessions hadlongevity of spike from 15 to 27 days, a big spike with 8.5 to 29.2cm in length and 1.9 to 8.5cm in diameter, number of bracts on a spike from 8 to 30, number of flowers on the bract from 2 to 7 flowers/bract, number of the spike on a clump from 1 to 4 spike/clump. In conclusion, all five accessions were well suited to develop decorative landscaping and cut flowers purpose.

Avian Metapneumovirus (aMPV) is one of the causative agents of respiratory disease complex in turkeys and chickens, which has been recently detected in Vietnam. Due to its novelty, a few published papers are available on preliminary results, describing the clinical disease, sero- and viral-positivity rates. This study aimed at providing more details about the molecular characterizations of the circulating virus by sequenced and then applied bioinformatics for data mining. Based on the sequence of partial attachment glycoprotein coding gene, 5/5 aMPV strains were classified as subgroup B. Though 5/5 strains belonged to the vaccine-derived lineage, all of them had differences at the nucleotide and amino acid levels compared to the attenuated strain of Nemovac vaccine available in Vietnam.

The study was conducted to compare and evaluate the cross-infection possibility of Edwardsiella ictaluricausing diseases in tilapia and Channel catfish. The strains ofE. ictaluriisolated from tilapia and Channel catfish were compared based on the biochemical characteristics, PCR confirmation, lethal doses and the possibility of cross-infection among other fish species. The results revealed that E. ictaluriisolated from tilapia and Channel catfish differed in 2/22 biochemical reactions (citrate utilization, Voges-proskauer) but they were identical in PCR assay. The virulence of E. ictaluristrains from tilapia was high when they were challenged to tilapia (LD50= 2.5 101CFU/fish) but remarkably decreased to Channel catfish (LD50= 2.0 106CFU/fish). Similarly, the isolates from Channel catfish exhibited a high virulence in this fish (LD50= 4.7 103CFU/fish) but reduced their pathogenicity to tilapia (LD50= 2.5 106CFU/fish). The primary result demonstrates that E. ictaluricausing diseases in Channel catfish and tilapia differed in several characteristics. However, they cause relatively high mortality of fish when cross-infection among fish species at high bacterial densities. Thus, biosafety is required to avoid the spreading of pathogens in the culture systems.

Feline Herpesvirus 1 (FHV-1), an enveloped double-stranded DNA virus, is one of the major pathogens of feline upper respiratory tract disease (URTD) and ocular disease. This study aimedto applyPCR techniques for diagnosis ofFHV-1. The study was conducted on 317 cats. The results showed that there were 62 out of 317 cats (19.56%)identified with the signs of FHV-1 infected cats by the clinical diagnosis method. Twenty-two out of 62 cats were positive with FHV-1 by PCR method accounting for 35.48%.Twenty-two out of 317 cats were positive with FHV-1 accounting for 6.94%compared with a total of the investigated cats. The Feline Herpesvirus -1 infection rate in cats < 12 months higher than adult cats and FHV-1 infection rate in unvaccinated cats higher than vaccinated cats. The disease was clinically manifested by severe depression, anorexia, ocular discharge, nasal discharge, sneezing, conjunctivitis, keratitis. In addition, some cats have had oral ulceration and fever.Almost all cats with FHV-1 have presented a slight increase of white blood cells (17.77 ± 0.89 103/µl).

Cold water aquaculture has been introduced to Vietnam in 2002, it was initially flourished in Sa Pa, but it has hitherto been cultured in 25 provinces, and typically grown in the Central Highland regions. The Highlandis known as a drought area and lacks waterin the dry season, but cold water aquaculture has been developed, hence it should be supported by the authorities. Through the survey of current status of cold water aquaculture conducted in 5 provinces in the Central Highlands in the two rainy and dry seasons from 2018 to 2020 on the basis of collecting primary and secondary information. The results showed that in the Central Highland region, the main cold-water aquaculture in Da Lat, Lam Dong provinces with aquatic farming of 2 species including sturgeon and salmon, in which the salmon species tends to be narrowed in cultivation area. The main limitations of cold water aquaculture in these regions are deficient source of cold and clean water in the dry season, and lack of capital for infrastructure investment as well as limitted the highly qualified human resources. The proposed solutions need to have the specific planning of aquatic farming areas in pratice and improve the scientific and technical level for managers, cold-water aquaculture farmers, promote each chain link in production and consumption of cold water fish.

This study was conducted from September to November of 2019 and 2020 to evaluate the heavy metal accumulation and health risks of the irrigated leafy vegetables Brassica juncea L,Basella alba L,Lactuca sativagrown from other sources along Cau Bay river, the section flowing through Da Ton commune, Gia Lam district, Hanoi. The contents of heavy metals (Cd, Pb, Cu, Zn) in water samples, soil samples and vegetable samples were determined with methods of atomic absorption spectroscopy (AAS). The analysis results showed that the productivity of leafy vegetables was increased when the water of Cau Bay river was used for irrigation together with increased accumulation of heavy metals in soil and vegetables compared to the vegetables irrigated with groundwater. Cd content in all 3 types of vegetables exceeded the allowable limit level, of which the accumulation of Cd and Pb in Brassica junceaL were higher than in Basella alba Land Lactuca sativa. However, the Cu, Zn contents were still at a safe level according to QCVN 8-2: 2011/ BYT and Decision 106/2007/QD-BNN. As the results showed the health risk index (HRI) and the target hazard quotient (THQ) when consuming 3 vegetables in this case are currently at the safe threshold.

Agricultural production is an area where land is the main means of production. Therefore, the comparison and selection of land use types (LUTs) suitable for land conditions is an objective requirement. The objective of this study was to evaluate the efficiency of agricultural production land uses in Krong Pa district to support farmers to select LUTs conformed to the region's natural conditions through the survey, interview households methods on economic, social and environmental aspects. Results showed that the land-use efficiency was at a medium level with rice, corn, cassava, tobacco, and a high level with cashew. In the future, farmers should focus on applying organic fertilizers, using drought-resistant cultivars to increase land-use efficiency and enhance the income of farmers in Krong Pa district.

This study presents the result of building the vertical oscillation model of the conjugate machine (sowing machine combined with fertilization for soybean (G4B2 machine) and tractor). The fluctuations of special points on the conjugate machine are described graphically through numerical methods by Matlab software when the parameters of the stimulus function change, in two cases: the continuous stimulating function and the single stimulating function cosine form. The tractor has a four-link hinge knuckle at the back, when working in the free state, the G4B2 machine oscillation affected by tractor oscillation is very small. The point near the wheel of the G4B2 machine has a smaller amplitude of oscillation than the remote point.It is necessary to decrease the feeding speed when combining the machine through the rough ground with large amplitude (h0 > 0.15m) and small steps (S0 < 1.0m).

The Bacillusspecies have become an increasingly important group of microorganisms with many applications such as environmental pollution treatment, traditional fermented products, pharmacy, etc. This study collected 66 strains of Bacillusfrom the wastewater samples of rice vermicelli production families at Phu Do to build up a collection of strains of this genus. The activities of extracellular enzymes of 66 isolates were investigated. The results showed that 26/66 strains secreted all three extracellular enzymes as protease, amylase, and cellulase with the largest substrate resolution ring diameters of 18.3, 20.8 and 20.9mm, respectively. Among them, four different strains NTB2.1, NTB2.3, NTB2.11, NTB5.7 were more active in biofilm formation than others based on the crystalline purple dye method. The data from measurement of absorbability at 570nm (OD570) wavelength showed greater than or equal to 3.17. In addition, these strains inhibit the growth of pathogenic microorganisms such as E. coli, Salmolellaand these strains were not antagonized to each other.

Spirulina (Arthrospira platensis)is a species of Cyanobacteriaand is widelycultivated for functional foods, cosmeticsand aquaculture feed due to its rich protein, pigments, vitamins, unsaturated fatty acids and trace elements. In Vietnam, Spirulinawasfirst studiedin the late 1970s, mainlyfocused oninvestigating environmentaland nutritive factors aswell asculture techniques. However, very few studies on isolation, identification and characterization of native strain have been done. With the aim of exploiting the indigenous genetic resources, a strain of Cyanobacteria distributed in Van Quan lake (Hanoi) was isolated, identified and culturedinthe medium ofHoagland, BBM, BG-11, ½ Chu-10 and Zarrouk. Bymorphological analysis using optical and electron scanning microscopy combined with 16S rRNA sequence analysis, theisolated strain was identified as Arthrospira platensis. As the results attained, except for Zarroukmedia, this speciescan grow well inin BG-11and BBMmedia. The study provided an initial scientific basis for exploiting indigenous genetic resources for functional foods, cosmeticsand aquaculture feeds.

NAC transcription factors have been regarded as one of the largest families of transcriptional regulators in plants. It has been demonstrated that NAC families played an important role in various biological processes in crops, particularly in abiotic stress response. This review summarizes the information of NAC families in numerous plant species. The functions of several NAC genes involving in the improvement of stress tolerance are discussed. Finally, some research orientations are proposed for further functional characterization of NAC gene for the crop breeding strategy adaptable to the climate change.

Use of insects as animal feed has been increasing significantly in the world and considered to be a potential development pathway in Vietnam to substitute protein-rich feed of animal and plant origin. The objectives of this paper is to review and evaluate the biological characteristics, nutritive value, and potential use of several edible insect species as animal feed. Black soldier fly larvae, mealworm, silkworm, locusts, and crickets are the most common species that have been used widely and the greatest potential in term of nutritive value of crude protein and fat contents with 42.1-63.3 and 8.5-36% respectiverly, rich in lysine and threonine. Partial or total supplement of fish meal or soybean meal with insect meal in the poultry and pig diets resulted in similar or even better production performance and meat quality. Some risks of food safety such as microbiological, toxic, and heavy metal contamination should be carefully eliminated during the rearing, harvesting, processing and preserving of insects. Further assessment of the potential and effects of insect replacement in different animal diets are requested to develop a noval and safe source of protein - rich feed material with acceptable production cost.

Vermiculture and earthworm use as animal feed have been globally developed; however, in Vietnam, vermiculture has been spontaneously developed and not yet become a commercial industry. The objective of this paper is to highlight and evaluate the biological characteristics, nutritive values, harvesting and processing methods of some earthworm species and their use in animal feed. Currently, three main earthworm species popularly cultured in Vietnam are Eisenia fetida, Eudrilus eugeniae, and Perionyx excavatus), of which Eudrilus eugeniae is the most important species in producing protein biomass. Earthworms are nutrient-rich feed (51.62-69.8 % crude protein, 5.8-12.0% crude fat in dry matter) with sufficient amino acid composition and vitamins. Among the various methods of earthworm processing, drying and hydrolysis are the most appropriate and popular. We should minimize the risks of heavy metal residue, microbial and parasitic contamination, and utilize at a proportion below the recommended doses (15% in chicken diet and 25-30% in fish diet). Further studies should focus on improving the processing methods to produce a safe and feasible source of animal feed with acceptable production costs.