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Prey Preference and Feeding Performance of the Predatory Mite Amblyseius largoensis Muma (Acari: Phytoseiidae) on Four Pest Mite Species under Laboratory Conditions

Duong Thi Nga, Ho Thi Quynh Trang, Dang Thi Ngoc Kiem, Nguyen Duc Tung, Ho Thi Thu Giang

Date Received: 15-11-2025 / Date Accepted: 22-12-2025 / Date Published: 23-01-2026
Amblyseius largoensis is a polyphagous predatory mite commonly found on citrus crops in northern Vietnam. This study evaluated its feeding capacity on the eggs, I mmature stages, and adult females of four prey mite species: Schizotetranychus hindustanicus, Tetranychus cinnabarinus, Panonychus citri, and Carpoglyphus lactis. Laboratory assays were conducted under two conditions: no-choice and choice tests. In the no-choice assays, A. largoensis consumed the highest number of C. lactis eggs, followed by T. cinnabarinus, whereas S. hindustanicus eggs were consumed the least. Conversely, the immature stages and adult females of S. hindustanicus were preyed upon in the greatest numbers. In the choice assays based on developmental stages of each prey species, A. largoensis preferentially consumed the eggs of P. citri, T. cinnabarinus, and C. lactis. For S. hindustanicus, the immature stage was the most heavily consumed. When prey species were offered simultaneously within the same developmental stage, C. lactis eggs showed the highest selection rate, while the immature and adult female stages of S. hindustanicus exhibited the highest selection rates among their respective categories. Overall, the results highlight the strong potential of A. largoensis as a biological control agent against pest mites on citrus. The findings also suggest that C. lactis could serve as an effective alternative prey for mass-rearing this predatory mite at a commercial scale.
DOI: https://doi.org/10.31817/tckhnnvn.2026.24.1.03
Identifying Consumer Preference for Milled Rice Quality in The Red River Delta

Nguyen Trong Khanh, Nguyen Van Hoan

Date Received: 29-09-2014 / Date Accepted: 20-11-2014 / Date Published: 06-08-2025
Over the last years, the demand for good quality of milled/white rice in the Red River Delta (RRD) of Vietnam has been increasing rapidly. To meet that demand, breeding new varieties with fine grain quality, suitable for cultivation conditions and climate of the RRD is of crucial significance and a prerequisite. Identifying criteria for breeding good quality rice can help rice breeders to keep breeding programs on track. From the results of investigating consumer preferences and the consumption of good quality rice in the market as well as evaluating agronomic characteristics and milled rice of quality varieties accepted by market, selection criteria for quality varieties for the RRD were established. The main criteria include early maturity, stable yield (5.5-7.0 tons/ha), low to moderate amylose content (17-23%) and fragrance. However, there were no strict requirements for grain length and grain shape and the breeders can select varieties that have long, medium or short grain.
DOI: https://doi.org/10.31817/tckhnnvn.2014.12.8.
Consumer Preference and Factors Affecting the Intention to Buy Fresh Cherry Tomatoes: Empirical Evidences from Thai Binh City, Vietnam

Ngo Minh Hai, Vu Quynh Hoa

Date Received: 16-04-2025 / Date Accepted: 24-12-2025 / Date Published: 23-01-2026
This study aimed to analyze consumer preferences and the factors influencing the purchase intention of fresh cherry tomatoes in Thai Binh city. Based on a survey of 100 consumers, logistic regression analysis was applied. The results indicate that knowledge about the health benefits of cherry tomatoes was still limited. Consumers preferred cherry tomatoes that are red in color (61.4%), round in shape (68.2%), and mildly sweet in taste (67.0%). Household income and expenditure on food were positively associated with purchase intention (β = 0.275; P <0.05 and β = 1.734; P <0.01). In addition, attention to freshness, safety, and traceability of origin also exerted a positive influence. Notably, general knowledge and knowledge about health benefits played a crucial role in promoting purchasing behavior (β = 1.345; P <0.1 and β = 0.685; P <0.05). Based on these findings, the study proposes policy recommendations on strengthening communication strategies, enhancing product quality, and expanding distribution channels that align with consumer preferences and behaviors.
DOI: https://doi.org/10.31817/tckhnnvn.2026.24.1.08
Evaluation for Growth, Development and Yield of Some Melon Varieties Introduced from China in Gialam, Hanoi

Vu Van Liet, Hoang Dang Dung

Date Received: 09-01-2011 / Date Accepted: 20-04-2012 / Date Published: 13-06-2025
Evaluation was carried out on growth, development and yield of three musk melon varieties introduced from China in Hanoi University of Agriculture, in 2011 Autumn - Winter season. The results show that all of varieties have morphological characteristics as diameter of fruit, weight of fruit, colour of fruit of skin meeting the consumers’ preference. These varieties show good growth potential, hight pest resistance, with marketable yield of 21.0 to 34.3 tons / ha.
DOI: https://doi.org/10.31817/tckhnnvn.2012.10.2.
Biological and Ecological Studies of the Ladybird Beetle Scymnus hoffmanniWeise (Coleoptera: Coccinellidae)

Ho Thi Thu Giang, Nguyen Hong Thanh

Date Received: 10-05-2012 / Date Accepted: 28-07-2012 / Date Published: 13-06-2025
The ladybird beetle, Scymnus hoffmanni, is a potential predator of aphids. The life cycle and adult fecundity were examined at laboratory. Life cycle of S. hoffmanni was 18.54 days for larvae reared on maize aphids, shorter than those reared on soybean aphids (19,92 days). Oviposition period lasted 19 days. Number of eggs deposited by female were 179.72 eggs. The number of maize aphids killed by S. hoffmanni 4th instar larvae and adult per day were 8.34 and 12.84, respectively. Maize aphids were preferred by S. hoffmanni in a prey preference test. Results obtained from this study provide basis for research on the utilization as predator in the biological control of aphids species.
DOI: https://doi.org/10.31817/tckhnnvn.2012.10.4.
PREDICTION MODELS FOR COLOUR CHANGES IN ORANGE FLESHED SWEET POTATO (Ipomoea batatas L. Lam.) DURING HOT AIR DRYING

Hoang Quoc Tuan, Le Canh Toan

Date Received: 27-06-2015 / Date Accepted: 11-03-2016 / Date Published: 12-06-2025
The main objective of this study was to investigate the effect of different temperatures of hot air drying on the quality attributes of orange fleshed sweet potato including colour parameters and colour sensory quality. The drying experiments were carried out at five air temperature of 40, 50, 60, 70 and 80oC. The colour parameters, L(whiteness/darkness), a(redness/greenness) and b(yellowness/blueness) for colour change of the materials were quantified by the Hunter Lab system. These values were also used for calculation of total change (E), hue angle, chroma and browning index. A consumer preference test was conducted with 80 consumers to assess the colour quality of five dried orange fleshed sweet potato samples. Relationship between colour sensory scores of consumer’s taste and quantification of three Hunter parameters using least square regression indicated that all colour values significantly affect colour quality ranking of dried orange fleshed sweet potato. The zero-order model appeared best suited to explain the colour change kinetics during hot drying orange fleshed sweet potato slices at 70oC.
DOI: https://doi.org/10.31817/tckhnnvn.2016.14.3.
Research Results on Breeding Fresh Wax Gourd VC21 Cultivar

Nguyen Dinh Thieu, Doan Xuan Canh, Ngo Thi Hanh, Tran Văn Quang

Date Received: 12-08-2022 / Date Accepted: 22-11-2022 / Date Published: 04-07-2025
The study aimed to evaluate agro-biological characteristics, yield, quality, and combining ability of self-inbreeding lines and to select F1 hybrid waxgourd combinations through survey and variety comparison experiments at Field Crops Research Institute, Hai Duong Province. Based on combining ability evaluation of 31 lines of fourth self-inbreeding generation,6 wax gourd lines were selected, namely BA6-3-7, BB3-4-5, BB5-6-4, BB7-3- 6, BF5-6-4 and BF9-3-2 with high general combining ability in terms of yield. At the same time, a combination of hybrid wax gourd designated D5/D2 (BF5-6-4/BB3-4-5; named VC21) was selected. The VC21 wax gourd grew well and had good resistance to downy mildew and powdery mildew in both spring-summer and autumn-winter cropping seasons. The VC21 variety had a growth period of 70-75 days from planting to the first harvest, about 105-110 days to the end of harvest and plant height of 370.9-405.2cm. The fruit weight was 1.45-1.51kg and yield of 50.04-57.76 tons/ha. The gourds showed dark green skin, light green flesh with dry matter content of 4.8%, fiber of 17.30%, total sugar of 2.45% and vitamin C content of 4.75mg. VC21 wax gourd variety had fruit shape, fruit weight and quality suitable to consumer preference (fruit length of 39.7-42.8cm, fruit diameter of 7.5-7.8cm, flesh thickness of 2.3-2.5cm).
DOI: https://doi.org/10.31817/tckhnnvn.2022.20.11.
Tourists’ Preferences toward Ecotourism Product and Biodiversity Conservation in Bavi National Park

Thai Thi Nhung

Date Received: 05-05-2021 / Date Accepted: 29-07-2021
This paper analyzed tourists’ preferences for ecotourism products associated with Biodiversity Conservation in Bavi National Park to support the decision-makers in ecotourism development process. Choice experiments were employed to examine the preferences of 180 tourists for the attributes of ecotourism products associated with Biodiversity Conservation and to estimate their willingness to pay for these ecotourism attributes. Using a Conditional Logit Model, the research results indicated that tourists had a preference for ecotourism products with all attributes except for visiting without exploiting traditional medicinal plants of the Dao ethnic minority.The tourist’s marginal willingness to donate to biodiversity conservation at VND5000 /time was VND100.7 thousand. The study also revealed that tourists were willing to donate for biodiversity conservation activities even higher than donation level suggested by the Park.
Biological and Ecological Characteristics of Cowpea Weevil Callosobruchus maculatusFabricius (Bruchidae: Coleoptera)

Ho Thi Thu Giang, Nguyen Bich Hoa

Date Received: 27-11-2020 / Date Accepted: 20-01-2021
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.
Learner Profile Model –A Whole Approach

Phan Thi Thu Hong, Nguyen Van Hoang

Date Received: 04-10-2013 / Date Accepted: 22-12-2013
An intelligent learning environment (ILE) can adapt the educational interaction to the specific needs of the individual learner according to learner profile. Learner profile is all information which the system holds about the learner. The learner profile also provides guidances and supports to teachers and the assessment systems. Therefore, learner profile has become an interesting field in e-learning researches. The main problems in learner profile researches are how to choose a good learner profile model (or what information should be stored?) and what is a good representation of learner profile for a specific user in a specific context? In this paper, we first review some e-learning systems and related papers to identify a good viewpoint which allow us to identify information which is needed in a learner profile. We then propose a learner profile model based on that view and how to present the information in the learner profile.

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