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Study on Maturation Broodstock Culture and Artificial Reproduction of Yellowcheek (Elopichthys bambusaRichardson, 1844)

Nguyen Hai Son, Vo Van Binh, Dang Thi Lua

Received: 25-03-2021 / Accepted: 22-06-2021
The study on maturation broodstock culture and artificial reproduction of yellowcheek (Elopichthys bambusaRichardson, 1844) was conducted from 12/2019 - 8/2020 at the National Freshwater Broodstocks Center. The aim of this study was to identify suitable foods for culturing maturation broodstocks, optimum hormone dose and appropriate incubation equipment for producing yellowcheek seeds. The results indicated that the use of chopped silver carp as food for culturing yellowcheek broodstock in the pond provided the higher maturation rate of broodstocks than using a food formulation consisting of 50% silver carp + 50% pellet feed and using 100% mixed pellet fish with 40% protein. Hormone dose of 60µg LRH-A + 10mg DOM/kg female gave the highest ovulation rate with the effect of hormones from 5-6 hours at 27-31C. Using Weiss incubators (Cycle tank) for incubating eggs showed a higher hatching rate (84.4%) and survival rate after 13 days (56.7%) in comparison with trays (68.7% hatching rate, survival rate 45.7%).
Investigation of Different Fertilization Methods in Artificial Reproductionof Spotted Scat(Scatophagus argusLinnaeus, 1766)

Nguyen Van Huy, Nguyen Anh Tuan, Le Van Dan

Received: 23-10-2023 / Accepted: 07-03-2024
This study aimed to determine the optimal fertilization method in the process of artificial reproduction of Spotted scat. A total of 18 pairs of parent fish were selected to participate in spawning trails based on the levels of gonad maturation. Females were injected twice at 24h interval by the hormone LHRH-a (20 and 50 µg/kg), while male fish were induced once by the hormone HCG (200 IU/kg) at the same time as the second injection of the female. After hormone injection, fish were randomly selected and assigned into 3 groups including Group 1: 6 pairs used to investigate natural fertilization in composite tanks; Group 2: 6 pairs used to investigate natural fertilization in a 6m3fabric cage located at the broodstock breeding area and group 3: 6 pairs fertilized by stripping method. The results showed that the natural spawning rates of groups 1 and group 2 were 66.7% and 83.3%, respectively. However, the rate of fertilized eggs in these groups was 0%. For fish in group 3, the spawning rate of fish was 83.3%, and the rate of fertilized eggs was quite high as 86.2%. This indicates that the “dry method” by stripping eggs and sperms from brooders is the optimal method for the artificial reproduction of Spotted scat up to the present time.
Investigation of Different Fertilization Methods in Artificial Reproductionof Spotted Scat(Scatophagus argusLinnaeus, 1766)

Nguyen Van Huy, Nguyen Anh Tuan, Le Van Dan

Received: 23-10-2023 / Accepted: 07-03-2024
This study aimed to determine the optimal fertilization method in the process of artificial reproduction of Spotted scat. A total of 18 pairs of parent fish were selected to participate in spawning trails based on the levels of gonad maturation. Females were injected twice at 24h interval by the hormone LHRH-a (20 and 50 µg/kg), while male fish were induced once by the hormone HCG (200 IU/kg) at the same time as the second injection of the female. After hormone injection, fish were randomly selected and assigned into 3 groups including Group 1: 6 pairs used to investigate natural fertilization in composite tanks; Group 2: 6 pairs used to investigate natural fertilization in a 6m3fabric cage located at the broodstock breeding area and group 3: 6 pairs fertilized by stripping method. The results showed that the natural spawning rates of groups 1 and group 2 were 66.7% and 83.3%, respectively. However, the rate of fertilized eggs in these groups was 0%. For fish in group 3, the spawning rate of fish was 83.3%, and the rate of fertilized eggs was quite high as 86.2%. This indicates that the “dry method” by stripping eggs and sperms from brooders is the optimal method for the artificial reproduction of Spotted scat up to the present time.
Cow - calf Reproduction Systems and Effect of Concentrate Supplement at Pre- and Post-partum on Reproductive Performance of Cross-bred Brahman CowsRaised in Households in Binh Dinh Province

Nguyen Xuan Ba, Dinh Van Dung, Nguyen Thi Mui, Nguyen Huu Van, Hoang Thi Mai, TranThanh Hai, David Parsons, Rowan Smith, Jeff Corfield, Laurie Bonney

Received: 18-04-2017 / Accepted: 26-07-2017
The objective of this study was to evaluate(1) cow - calf reproduction system and (2) effects of concentrate supplement at pre - and post partrum on reproduction performance of Brahman cows. Total 66 cattle raising households (10%) in Tay Giang commune, Tay Son District, Binh Dinh province) were surveyed. In addition, 255 Cross-bredBrahman cows were evaluatedforreproductiveperformance, and 163 calves were weighted from birth to 6 months of age. On - farm experiment and demonstration of the effect of pre- and post-partum supplementary feeding on cow-calf performance were conducted from January 2014 to December 2016. The survey results showed that the cow - calf system in the communes has been moving from extensive to semi-intensiveone. Cows accounted for 50% of cattle surveyed, of which 90% were Zebu crossbred. Cow feeding systems were mostly grazing and stall feeding (97%). A long calving interval (15.9 months), lack of nutrition for cows at pre - and post - partum, and poor feeding management were identified. The experiment showed that improved supplementation for cows at pre - and post - partum could shorten calving to conception interval from 212 to 176 days (P < 0.05). The on - farm demonstration confirmed that post - partum supplementation can reduce calving interval and the techniques were well accepted by farmers in the region.
Technical Advances in Reproduction: Applications in Medicine and Agriculture

Nguyen Van Thuan

Received: 18-04-2017 / Accepted: 26-07-2017
In mammals, reproduction is the ability to generate next generation through the fertilization of a mature egg and a sperm. Nowadays, with the development of modern reproductive biotechnology, several advanced techniques have been applied and able to generate new generations from somatic cellsandstem cells or from immature eggs and sperms. In the present paper, the advances in reproduction over the past 20 yearsare sumarized and presented including: (1) intracytoplasmic sperm injection (ICSI) and application of this method to treat infertility and production of transgenic animals, (2) round spermatid injection (ROSI) and itsapplication on treatment of infertility without spermatozoa, (3) Somatic cell nuclear transfer (SCNT), also known as animal cloning, and (4) the method to generate new generation by pluripotent stem cells injected into tetraploid blastocysts.The application potential of the modern reproductive methods in medicine and agriculturewas discussed.
Effect of Salinity on Reproductive Performance of SelectedBrackish Water NileTilapia Strain (Oreochromis niloticus)

Le Minh Toan, Vu Van Sang, Trinh Dinh Khuyen

Received: 27-09-2012 / Accepted: 18-12-2012
The experiment was carried out to evaluate the effects of salinity on fertility of selected brackish water Nile tilapia (Oreochromis niloticus) strain in 53 days. The experiment fish was arranged breeding in brackish water corresponding to three different salinity levels such as: 4 - 5‰, 8 - 10‰ and 14 - 16‰, the ratio of male: female tilapia was 1:2, each formula was repeated 3 times in 3 different tanks, stocking density was 4 individuals/m3 for each tank. Results show that the reproductive rate of females corresponding to 4 - 5‰ salinity was 26.2 ± 4.64%; 8 - 10‰: 17.86 ± 11.21% and 14 - 16‰: 6.88 ± 6.57%. The number of eggs per formula obtained after 7 times was obtained in 3 corresponding levels salinity was 5,229a ± 1,280 eggs, 2,721b ± 1,559 eggs and 923c ± 706 results. Relative fecundity 3 levels of salinity 4 - 5‰, 8 - 10‰ and 14 - 16‰, respectively, 4.3a ± 0.63 eggs/g fish/time was 3.36b ± 0.67 eggs/g female/times and 1.7c ± 1.27 eggs/g fish/time. Absolute fecundity of tilapia in salinity 4 - 5% was 829 ± 122.9 eggs/time delivery, salinity 8 - 10‰ of 678a ± 135,7 and at a salinity of 14 - 16‰ was 403b ± 154.5 eggs/female/delivery time. Natural frequency of females at 4 - 5‰ salinity 22.3 ± 2.23 days; 8 - 10% was 24.9 ± 3.7 days and 14 - 16‰ salinity was 25.7 ± 2.59 days. Experimental results showed that the breeding of tilapia at salinity level of 4 - 5‰ obtained the best reproduction, next to the level of salinity 8 - 10‰. Experiments show that the breeding of Nile tilapia at salinity level below 8 - 10‰ was high practical significance.
Estimatingthe Basic Reproductive Number and Vaccine Coverage for African Swine Fever Prevention in Large-scale Fattening Farms

Mai Thi Ngan, Vu Thi Ngoc, Truong Ha Thai

Received: 23-12-2021 / Accepted: 05-07-2022
African swine fever (ASF) is a highly contagious disease with a mortality of up to 100%, resulting in high economic losses. In Vietnam, ASF was first reported in February 2019 and quickly spread to all provinces. This study aimed to estimate the basic reproduction number (R0) and developed a dynamic model to explain how ASF spreads in the pig herd during the first epidemic year to suggest vaccine coverage level required to prevent future outbreaks. The outbreak data were collected from 6 large-scale fattening farms within the first wave of ASF outbreaks. Two methods were used to estimate the R0including the Exponential Growth method (EG) and Maximum Likelihood method (ML). The average R0values were estimated at 2.97 (95%CI: 2.44-3.59) and 3.18 (95%CI: 2.52-3.96), respectively. Based on the worst-case scenario, all pigs in a herd would be infected and removed within 50 days. The vaccination rate ranges from 75-94% of pigs in each farm depending on the vaccine effectiveness.
Influence of Artificial Diets on the Biological Characteristics of the Oriental Fruit Fly Bactrocera dorsalisHendel (Diptera: Tephritidae)

Nguyen Duc Tung, NguyenThiThuHuong, TranThi HongThuy, HoThiThuGiang

Received: 22-12-2023 / Accepted: 26-01-2024
This study aims to determine the most suitable artificial diet for rearing the Oriental fruit fly Bactrocera dorsalis. The experiment was conducted by evaluating the growth and development parameters of the Oriental fruit fly when reared in the laboratory with four artificial diets with main ingredient: yeast (TA1), wheat bran (TA2), rice bran (TA3), and ground longan (TA4). The results showed that B. dorsalisfemales reared on TA2 had the shortest lifecycle (29.75 days), while there was no significant difference in lifecycle when reared on the three other diets, with 34.23 days (TA1), 34.28 days (TA3) and 34.27 days (TA4). The daily oviposition and total reproduction of the female adults reared on TA2 were the highest, with values of 13.11 eggs/day and 587.40 eggs/female, respectively, significantly higher than the other diets. The net reproductive rate (R0) and intrinsic rate of increase (rm) were also significantly higher than the other diets. R0decreased in the order of TA2 (320.73), TA3 (264.55), TA1 (262.63), TA4 (258.78), while rmdecreased in the order of TA2 (0.131), TA1 (0.120), TA3 (0.116), TA4 (0.115). In conclusion, the diet with wheat bran as the main ingredient (TA2) proved to be the most suitable for the development, reproduction, and mass rearing of the Oriental fruit fly.
ẢnhhưởngcủatếbàohìnhchéntrongviệcthảitrừgiunNippostrongylusbrasiliensisở vậtchủđồngnhiễmvớiEimeriavermiformis

Bui Khanh Linh, Hayashi T

Received: 20-06-2014 / Accepted: 02-03-2015
Tế bào hình chén đóng vai trò quan trọng trong việc thải trừ giun Nippostrongylus brasiliensis (N. brasiliensis) thông qua việc tăng số lượng tế bào và tăng tiết chất nhầy ở ruột. Trong khi đó, cầu trùng Eimeria vermiformis lại làm giảm số lượng tế bào hình chén ở ruột và hình thành miễn dịch tế bào Th1 ở ruột thì N. brasiliensis lại sản sinh đáp ứng miễn dịch Th2. Bài báo này sẽ thảo luận những ảnh hưởng gây ra do tế bào hình chén ở chuột đồng nhiễm trong việc thải trừ N. brasiliensis. Nippostrongylus brasiliensis và Eimeria vermiformis được gây nhiễm cho chuột ICR. Kết quả cho thấy, việc thải trừ giun bị giảm ở chuột đồng nhiễm so với chuột đơn nhiễm và có liên quan đến số lượng của tế bào hình chén. Kết quả này cho thấy, Eimeria vermiformis có ảnh hưởng đến việc thải trừ Nippostrongylus brasiliensis và có thể thông qua hệ đáp ứng miễn dịch ở chuột đồng nhiễm.
Biological and Ecological Studies of the Ladybird Beetle Scymnus hoffmanniWeise (Coleoptera: Coccinellidae)

Ho Thi Thu Giang, Nguyen Hong Thanh

Received: 10-05-2012 / Accepted: 28-07-2012
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.
Comparing Morphological and Reproductive Biology Characteristics of Two Fresh-Water Snail Species, Pila politaand Pila gracilisfrom Dong Thap Province

Ngo Thi Thu Thao, Le Van Binh

Received: 31-10-2017 / Accepted: 25-12-2017
This study compared several morphological characteristics and reproductive biology of two fresh-water snail species, Pila polita(Pp) and Pila gracilis(Pg). The colors of the snail shells change over the stages in their life. With shell height <25 mm, Pp and Pg show green-yellow and green-dark color, respectively; with shell hight larger than 25 mm, Pp shell is green-dark and Pg is brown-yellow. Pila politaand Pila gracilisshow a close correlation between morphological characteristics such as shell height with shell width, shell height with total weight or shell height with meat weight. Results of broodstock conditioning and observations of some reproductive biology characteristics of two species showed that the weight and diameter of snail eggs, shell height and weight of newly hatched snails from Pila politawere higher than those from Pila gracilis(p<0.05).
Preliminary Results on Applications of Reproductive Technology for Developing Industrial Rabbit Breeding

Nguyen Thi Hong, Phan Ngoc Minh, Nguyen Thi Uoc, Duong Dinh Long, Nguyen Khac Tich, Nguyen Thi Hiep, Nguyen Thi Nhung, Nguyen Viet Linh, Bui Xuan Nguyen

Received: 18-04-2017 / Accepted: 26-07-2017
Rabbits are suitable for livestock development for poverty reduction and sustainable agricultural development. At present, the development of rabbit breeding in the mode of industrial reproduction is of concern ofmany farms. In this report, we introduce some preliminaryresults on oestrus synchronization, preservationofsperms, combination of oestrus synchronizationwithartificial insemination (AI) for controllingreproduction of New Zealand rabbit in Vietnam. PMSG treatment has significantly improved receptivity of the doesandtreatment with 40 IU and 60 IU were more effective than with 20 IU in oestrus synchronization. TCG was more effective than EX1 in protection of rabbit sperms at 4oC. Both pregnant rate and litter size using AI after oestrus synchronization were higher than natural mating after normal eostrus.
Effect of Different Dietary Protein Levels on Growth and Reproductive Characteristics of Artemia franciscana Vinh Chau

Duong Thi My Han, Nguyen Van Hoa, Nguyen Thi Ngoc Anh

Received: 20-08-2015 / Accepted: 22-01-2016
This study was conducted to evaluate the effect of dietary protein levels in formulated feeds on survival, growth and reproductive characteristics of Artemia franciscanaVinh Chau in laboratory conditions. Experiment consisted of 7 feeding treatments including of commercial shrimp feed No. 0 (control feed) and 6 formulated feeds containing 20, 25, 30, 35, 40 and 45% protein. The experimental process was divided into two phases (1) Communal culture,from day 0 until Artemiareachessexual maturity to determine survival and growth. (2) Individual culture,Artemiacouples were reared in 50-ml Falcon tubes to record their reproductive characteristics and life span. After 14 days of culture, survival of Artemiawas not affected by the feeding treatments, varying in the range of 87.2-95.4%; and the total length of Artemiaattainedbetween 7.00 and 8.04mm, of which the treatments from 25% to 35% protein had significantly higher values (P> 0.05) compared to other feeding treatments. The lifespan of Artemia females wassimilar among feeding treatments (44.6-48.6 days). The reproductive period, total brood number and total offspring per Artemiafemale in the 30 and 35% protein treatments were significantly higher (P> 0.05) than the control, 20% and 45% protein treatments. These results indicated that formulated feed containing 30 to35% protein could be suitable feed for growth and reproductive performance of Artemia franciscana.
Effects of Feeds Containing Different Protein Contents on Conditioning of Black Apple Snail (Pila polita) Broodstock

Le Van Binh, Ngo Thi Thu Thao, Vo Thi Kieu Diem

Received: 01-03-2018 / Accepted: 16-05-2018
The objective of the present study was to determine the effects of different protein contents in feedon the maturationand reproductive efficiency of black apple snail (Pila polita). Snail broodstocks were fed with 5 protein levels with triplicates for each as follow:15% (P15); 20% (P20); 25% (P25); 30% (P30) and 35% (P35). The broodstockswith shell height of 36.2 - 44.8 mm were reared in the tarpaulin tanks (1 × 1 × 1 m) atthe density of 60 individuals/tank and male: female ratio was 1: 1. After 90 days of culture, mean GSI of snails in P25 (13.90% in female; 5.10% in male) was higher than that of P20 (12.66%; 4.14%) and significantlydifferent(P < 0.05) with P15 (8.27%; 3.59%). Spawning frequency of broodstocks in P25 (1.06 clutch/week/m2), P20 (0.78 clutch/week/m2) wassignificantlydifferent(P < 0.05) compared to those in P15 (0.44 clutch/week/m2), P30 (0.61 clutch/week/m2) or P35 (0.47 clutch/week/m2). Snails in P25 also had the highest reproduction efficiency (206 eggs/clutch), P30 (189 eggs/clutch) and significantlydifferent(P < 0.05) from P15 (124 eggs/clutch), P20 (175 eggs/clutch) and P35 (154 eggs/clutch). The results showedthat processed foods with a protein content of 25% yieldedhigher maturity rate and reproductionefficiencyof black apple snail compared to other protein contentsin feed.
Effects of Chemicals and Induced Methods on Reproduction Efficiency of Mud Clam (Geloina sp.)from U Minh Thuong, Kien Giang

Ngo Thi Thu Thao, Danh Nhiet, Tran Ngoc Hai, Nguyen Xuan Niem

Received: 27-02-2018 / Accepted: 16-05-2018
Clam broodstocksGeloinasp were collected at U Minh Thuong areas, Kien Giang province to investigatethe effects of different spawning methods on efficiencyin the hatchery. The study consisted of3 experiments: 1) Using chemicals, 2) Changing temperature and 3) combining chemicals and temperature changes. Several indicators such as number of reproductive individuals, reproductive rate, survival, effective time and the numbers of eggs were significantly differentamong treatments (P < 0.05). Results showed that lowering temperature combined withflow through water system was most suitable for clam spawning withr 50%efficiency, high eggs/individual (1.203.000 ± 199.983)andshorter spawning time..
Conformationaland Performance Characteristics of Hon Chu Chicken

Saykham Souksanith, Dang Vu Binh

Received: 29-11-2018 / Accepted: 06-03-2019
The study was conducted to evaluate the conformationalcharacteristics and production performance of Hon Chu chicken, a major local chicken of Lao PDR. The assessment surveys were conducted in some households in the 3 neighboring villages of Luang Prabang. The experiments to evaluate conformation, performances of reproduction and production were conducted at Northern Luang Prabang Agriculture and Forestry College, Lao PDR. Results showed that Hon Chu chickens had small stature and variable body color patterns. Under free range conditions at households, the male and female body weight at 20 weeks of age was 780 and 670 g, respectively. The first laying age was over 7 months of age and egg production was 62 eggs/layer/year. Underconfinement conditions and mixed feeding, at 24 weeks of age, cock and hen weight was 2,171 and 1,858 g, respectively. At 30 weeks of age, the meat proportion was 71%, the ratio of the thigh meat was higher than the breast. The first laying age was 23rdweek with egg yield of 25 eggs in 13 laying weeks but small eggs (44 g), and thick eggshell.
Reproductive Biological Characteristic ofPuntioplites proctozystronin Bung Binh Thien, An Giang Province

Nguyen Hoang Huy, Au Van Hoa, Pham Thanh Liem

Received: 13-12-2021 / Accepted: 15-08-2022
To evaluate the reproductive biology of Puntioplites proctozystron at Bung Binh Thien, An Giang, females and males were captured to provide the detailed information on their reproductive biology in their natural habitat. The study was collected monthly by different fishing gear, starting from July 2018 to June 2019. At each sampling time, 60 samples were randomly selected with a length between 6.0-23.7cm to provide a continuous view of gonad development. The results showed that Puntioplites proctozystron can differentiate between male and female during spawning season. Fulton’s and Clark’s indices ranged from 2.00 to 3.97%, and from 1.77 to 3.60%, respectively. The highest indices were found in May and the lowest in January. Condition factor of the female was from 0.009 to 0.023, whereas those for the male ranged from 0.006 to 0.055. Female GSI ranged from 0.24 to 1.91%, that was highest in June 2019 and lowest in February 2019. Similarly, male GSI ranged from 0.19 to 0.51%, that was highest in June 2019 and lowest in March 2019. The average length of early-maturing fish was Lm50= 13.5cm. The absolute fecundity of Puntioplites proctozystron was 32,104 ± 17,501 eggs/female and its relative fecundity was 298,456 ± 140,909 eggs per kg of female with an average diameter of egg at stage IV of 0.97 ± 0.04 mm. The fish spawn annually, but reach maximum levels in June.
Study on Spawning Stimulation of Black Apple Snails (Pila polita)

Le Van Binh

Received: 25-06-2019 / Accepted: 13-08-2019
This study was carried out to examine the effects of different stimulation methods on spawning of the black apple snails, Pila polita. The experiments were arranged in 1 m3 tanks (1×1×1 m) at density of 15 pairs of broodstock snail/tankwhere water column at the beginning was 40 cm high. Experiment 1was done with 4 different water exchanging regimes: 1) Discard 25% water (D25); 2) Discard 50% water (D50); 3) Discard 75% water (D75) and 4) Discard 100% water (D100). Results showed that the highest spawning rate occurred at D75 (60.6%), following by the D50 (58.3%) and these were significantly different from D25 or D100 (P <0.05). The broodstock snails at D75 released highest egg clutches and reproductive efficiency (9.08 clutch/m2; 3.03 clutch/day/m2) and statistically significant different from D25 and D100 (P<0.05). Experiment 2 was implemented in the same condition as the early one (started with 40 cm of water level in the experiemental tanks) but with 4 different spawning stimulation methods: 1) Adding 25% water (A25); 2) Adding 50% water (A50); 3) Adding 75% water (A75) and 4) Addiing 100% water (A100). The spawning rate in A50 (82.2%) was significantly higher (P <0.05) than that inA25 (66.7%) and A100 (64.4%). The numbers of released egg clutches and reproductive efficiency of the snails in A50 (12.3 clutch/m2; 4.11 clutch/day/m2) were significantly higher than those (P<0.05) from A25 (10.1 clutch/ m2; 3.33 clutch/day/m2) or A100 (9.7 clutch/m2; 3.22 clutch/day/m2). The research results show that the spawning stimulation by renewing 75% of water or adding 50% of water volume gave the higher reproductive efficiency than other methods.
Genetic Structures of Estrogen Receptor (ESR) and Prolactin Receptor (PRLR) Genes in Landrace and Yorkshire Populations at DABACO Nucleus Pig Breeding Company

Nguyen Chi Thanh, Tran Xuan Manh, Nguyen Van Hung, Luu Thi Trang, Phan Xuan Hao, Vu Dinh Ton

Received: 02-05-2019 / Accepted: 30-09-2019
Litter size of pigs is an important economic trait, but its heritability is relatively low,at approximately 0.1. In addition, litter size trait can only be measured on female pigs at mature age. Therefore, genetic improvement by phenotypic selection is less effective, and at slow rate. In previous literature, it is found that ESR and PRLR genes are two QTLswith large effects on litter size in pigs. Of the two alleles A and B at ESR locus, allele B shows a positive effect on the litter size trait,while of the two alleles A and B at PRLR locus, allele A is benefical to the trait. Landrace and Yorkshire, which are imported, are two major breeds in Vietnam. The current study aimed to evaluate genetic structures of ESR and PRLR genes in two pig populations of Landrace and Yorkshire reared at the Dabaco nuclear breeding pig company, and thus examine the effects of ESR and PRLR genes on reproduction traits of the two pig populations. It was found that all three genotypes,AA, AB and BB at ESR and PRLR loci,were present in both the populations of Landrace and Yorkshire pigs. At ESR locus, allele frequency of B in the Landrace population (0.184) was lower than in the Yorkshire population (0.413). The frequency of homozygous genotype BB was 0.041 for the Landrace population and 0.655 for the Yorkshire population. At PRLR locus, allele frequencies of A and B were quite similar for the two populations. Allele frequency of A was 0.483 for Landrance and 0.516 for Yorkshire. Allele frequency of B was 0.517 for Landrance and 0.484 for Yorkshire.
Influencesof Host Plants on the Biology of Two-Spotted Spider Mite Tetranychus urticaeKoch (Acari: Tetranychidae)

Tran Ngoc Cam, Nguyen Duc Tung

Received: 29-11-2019 / Accepted: 31-01-2020
Tetranychus urticaeKoch (Acari:Tetranychidae) is a dangerous peston manycropsin Vietnam and worldwide. The objective of this study wasto find outthe biological and ecological characteristics of this harmful two-spotted spider miteas a basis to launch the effective pest managing strategies in the future. In this study, the development time, reproduction and population growth of two-spotted spider mite reared on the green bean variety TN38 and cucumber F1 (VA.103) were investigated at 23.5C. Results showed that the total immatures of male T. urticaewere not significantly different when reared onthebean and cucumberfor11.93 days and 11.73 days, respectively. However, the life cycle of female T. urticaereared on bean (13.69 days)wassignificantly shorter than its rearingon the cucumber (15.65 days). The oviposition rate and total number of eggs laid by the females fed on the bean (6.00 eggs/female/day and 62.69 eggs/female, respectively) were significantly higher than that of the female fed on cucumbers (3.13 eggs/ female/day and 29.35 eggs/female, respectively). The generation time (T) of the two spotted spider mite reared on bean (17.72 days)was significantly shorter than that on cucumbers (19.98 days). The net reproductive rate (R0) of the female fed on bean (45.02 females/female) was much higher than that of females reared on cucumbers (21.97 females/female). The intrinsic rate of natural increase of T. urticaeon bean was 0.210 which showed asignificantly higher than in cucumber (0.150).

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