Penaeus Monodon Larvae Research Articles

Automatic Penaeus Monodon Larvae Counting via Equal Keypoint Regression with Smartphones.

Today, large-scale Penaeus monodon farms no longer incubate eggs but instead purchase larvae from large-scale hatcheries for rearing. The accurate counting of tens of thousands of larvae in these transactions is a challenging task due to the small size of the larvae and the highly congested scenes. To address this issue, we present the Penaeus Larvae Counting Strategy (PLCS), a simple and efficient method for counting Penaeus monodon larvae that only requires a smartphone to capture images without the need for any additional equipment. Our approach treats two different types of keypoints as equip keypoints based on keypoint regression to determine the number of shrimp larvae in the image. We constructed a high-resolution image dataset named Penaeus_1k using images captured by five smartphones. This dataset contains 1420 images of Penaeus monodon larvae and includes general annotations for three keypoints, making it suitable for density map counting, keypoint regression, and other methods. The effectiveness of the proposed method was evaluated on a real Penaeus monodon larvae dataset. The average accuracy of 720 images with seven different density groups in the test dataset was 93.79%, outperforming the classical density map algorithm and demonstrating the efficacy of the PLCS.

Growth and Lipidomic Analyses of Penaeus monodon Larvae Supplemented With Aurantiochytrium limacinum BCC52274

Long-chain polyunsaturated fatty acids (LC-PUFAs) are essential for growth and health of larval marine animals. Marine animals have a limited capability for LC-PUFA synthesis, and the larvae must obtain LC-PUFAs from diet. The protist Aurantiochytrium limacinum (AL) is abundant in 22:6 n-3 (docosahexaenoic acid, DHA), 22:5 n-3 (docosapentaenoic acid, DPA) and 16:0 fatty acids, which qualifies it as an LC-PUFA source for feed application. Therefore, in this study, a common feed containing lower amounts of total LC-PUFAs, Thalasiosira weissflogii, was replaced with AL at graded proportions and supplied to Penaeus monodon larvae from mysis (M) 1 to post-larval (PL) 2 stages to supplement LC-PUFAs in the diet. After that, all shrimp from PL2 to PL12 were continuously reared and subjected to the same diet regime, which was a combination of Artemia and commercial dried feed. The AL-supplemented PL2 shrimp demonstrated marked accumulation of the key fatty acids present in AL—16:0, DPA and DHA. The supplemented larvae showed no difference in growth during the supplementation period from M1 to PL2; however, average body weight and biomass were increased in PL12 shrimp that were fed earlier with AL. Lipidomic analysis revealed that profiles of fatty acids but not lipid classes/subclasses in PL shrimp reflected the supplied diet. The main saturated fatty acid (SFA, 16:0) predominantly accumulated in acylglycerols, which are energy-reserve lipids, in PL2 shrimp. Both LC-PUFAs (DHA and DPA) were preferentially deposited in phospholipids or structural lipids. Furthermore, while the amounts of both LC-PUFAs increased along with the amount of supplied AL, that of the SFA did not. This suggests that LC-PUFAs were prioritized to be stored over SFA when both types of fatty acids were present in high amounts. This analysis substantiates the importance of LC-PUFAs and provides an insight into how different types of the dietary fatty acids were differentially accumulated in lipid classes and subclasses for their biological functions.

A preliminary experiment on production of dsRNA by in-vivo and its application to tiger shrimp Penaeus monodon larvae for survival enhancement

RNA interference (RNAi) is one of the most recent tools against shrimp viral infection by gene constructs of dsRNA induction. This study aimed to produce dsRNA by in-vivo method and to analyse the effect of its application to tiger shrimp larvae. The dsRNA production was conducted by cloning of genes encoding VP15 and VP24 of WSSV into L4440 vector containing T7 promoter, then transformed to Escherichia coli and grew in LB media for mass production. The bacteria were in-activated using heat-killed bacteria method by immersion at 80°C for 5, 10, and 15 min. Before WSSV-challenge test, tiger shrimp PL-12 were vaccinated by immersion using in-activated bacteria in concentration of 1.3×108 cell/mL for 30 min as a treatment and without vaccination was as a control. The results showed the successful production of VP-dsRNA by in-vivo. In-activated bacteria was effective at 5 min, since dsRNA did not damage. Survival of larvae at 5 days post challenge (dpc) in VP15-dsRNA was relatively higher (28.3%) compared to control (24.4%), and application of VP24-dsRNA also showed higher survival (86.9%) compared to control (83.1%) at 10 dpc. The result implied that the application of dsRNA exhibited a sign of potential way to produce resistant larvae.

Effects of live microalgae and algae powder on microbial community, survival, metamorphosis and digestive enzyme activity of Penaeus monodon larvae at different growth stages

Most hatcheries use live microalgae and algae powder for artificial rearing; however, the effects of these different diets on the rearing process and bacterial communities is not clear. In order to investigate the effects of live algae and algal powder on the larval culture of Penaeus monodon. Two kinds of live algae (Chaetoceros muelleri, Thalassiosira weissflogii) and Spirulina powder were used to feed larvae in this study, and the effects on the environmental parameters of water, the digestive enzymes activity of larvae and the bacterial community from the zoea stage to the post larval (PL) stage were explored. The results revealed that feeding larvae with C. muelleri significantly improved the enzymatic activity of amylase and the survival rate of the larvae, and significantly reduce the concentrations of NH4-N, NO2-N and the quantity of Vibrio in the water (P < 0.05). Feeding with T. weissflogii significantly improved the enzymatic activity of lipase and pepsin, and the percentage of metamorphosis (P < 0.05). It suggested that adding live microalgae was beneficial in increasing the diversity of the bacterial community in larvae. Cyanobacteria and Patescibacteria were dominant bacteria in the algal solutions of C. muelleri and T. weissflogii. The entire rearing environment was dominated by two phyla: Bacteroidetes and Proteobacteria. Virgulinella fragilis, the bacteria present in the liquid of C. muelleri and T. weissflogii, accounts for a high proportion of bacteria in the rearing water at the zoea stage. The bacterial community in the zoea stage showed significant negative correlations with NH4-N and NO2-N (P < .05), whereas the bacterial community in the PL stage showed significant positive correlations with NH4-N and NO2-N (P < .05). Saprospiraceae and Microbacteriaceae in the water were significantly positively correlated with NH4-N and NO2-N (P < .05). Feeding larvae with C. muelleri and T. weissflogii and Spirulina powder could increased the abundance of Microbacteriaceae, Devosiaceae and Saprospiraceae at the family level, and increased the abundance of Pseudoalteromonas, Roseovarius and Nautella at genus level. In conclusion, feeding larvae with live microalgae could improve the percentage of metamorphosis and survival rates of larvae by improving the external water environment, enhancing digestion, and regulating bacterial community.

EKSTRAK BUAH MANGROVE (Sonneratia alba) PADA Artemia salina DALAM MENGHAMBAT INFEKSI Vibrio harveyi TERHADAP SINTASAN BENUR UDANG WINDU (Penaeus monodon) SECARA INVIVO

Vibriosis disease Vibrio harveyi often drops Penaeus monodon production on the traditional coastal ponds of North Kalimantan. The purpose of this study was to find out the active compound extract of Sonneratia alba fruit inhibiting the infection of Vibrio harveyi, which was tested on the larvae of Penaeus monodon in post larvae 12 through the bioerichment of natural feed Artemia salina. This study used an experimental method performed with a Completely Randomized Design (CRD) of 4 treatments and 3 replications. The results showed mangrove fruit extracts containing alkaloids, phenol hydroquinone, flavonoids, saponins, steroids and tannins. Artemia salina bioenrichment succeeded in increasing the survival of Penaeus monodon larvae 78.33% in treatment III (20 ppm). The results of water quality measurements indicate the range at the normal limit for the life of the Penaeus monodon larvae. Keywords : Penaeus monodon, Artemia salina, Vibrio harveyi, Extract Sonneratia alba

Black tiger shrimp larvae (Penaeus monodon) that received eggshell powder in diet exhibit decreasing of growth and survival rate

The objective of the present study was to investigate the effect of eggshell powder supplementation in diet on the growth and survival rate of black tiger shrimp, Penaeus monodon larvae. A total of 600 shrimp larvae (PL 12) was used with five treatment levels and four replications. The shrimp fed with 42% of crude protein, feeding frequency three times a day at 08.00; 14.00; 18.00 pm and 5% feeding rate. The dietary treatments were A (0%), B (3%), C (6%), D (9%) and E (12%) fed for thirty days. Results showed that the supplementation of eggshell powder in diet had a significant effect on weight gain, length gain, specific growth rate, and survival of black tiger shrimp larvae. Duncan's advanced test showed that the optimum dose of eggshell powder was found in treatment A (0% eggshell powder) with weight gain, length gain, specific growth rate, and survival rate at 0.0301±0,0013 g, 12.41±0,56 mm, 12.82±0,16 %/day, and 94.17±1,66%, respectively. Hence, it can be concluded that the supplementation of eggshell powder may decrease the growth and survival rate of black tiger shrimp larvae.

Neuroendocrine and immunotoxicity of polyaromatic hydrocarbon, chrysene in crustacean post larvae

Polyaromatic hydrocarbons are a group of chemical pollutants which cause a significant threat to the living organisms in estuaries and marine ecosystems. We report the effect of chrysene, a major PAH pollutant found in Cochin Estuary along the southwest coast of India, on the neuroendocrine and immune gene expression of the post larvae (PL-25) of Penaeus monodon. The PL- 25 of P. monodon were administered with feed coated with increasing concentrations of chrysene (1, 2 and 3 µg/g) for 10 days and the gene expression was studied on 7th, 11th and 15th day. The PL exposed to chrysene showed moulting stress and changes in the levels of moult-inhibiting hormone I (MIH I) indicated by irregular moulting in the experimental tanks. At the molecular level, the higher concentration of chrysene induced two-fold upregulation of neuroendocrine (MIH I) and downregulation of immune (ProPO and crustin) gene on the 7th day of exposure. The expression of MIH I gene reduced on withdrawing the experimental feed (on 11th day), while continued downregulation of ProPO and crustin were observed on the 11th day. The results of the present study indicate that the microgram levels of PAH can impinge the neuroendocrine and immune system of the P. monodon, which may induce morbidity and mortality to the larvae in polluted coastal ecosystems. Therefore, more attention may be given to avoid PAH pollution in the estuaries to maintain a healthy ecosystem and to protect the animals from extinction.

Effect of Chromolaena odorata as bioactive compound in artificial diet on survival rate of tiger prawn Penaeus monodon

The leaves of Chromolaena odorata can be used as alternative bioactive compounds to address high mortality in shrimp due to outbreaks of Vibrio sp. during both larval rearing and grow-out. The study aimed to determine the effect of Chromolaena odorata leaves on the survival and growth performance of tiger prawn Penaeus monodon larvae. Four different formulated diets with different concentrations of Chromolaena odorata leaves (1250 mg/kg, 1500 mg/kg, 1750 mg/kg) and a control (0 mg/kg) were fed to tiger prawns infected with Vibrio harveyi. Data were collected on total hemocyte count (THC), phenoloxidase (PO) and survival rate. One way ANOVA was applied for statistical analysis. The results show that Chromolaena odorata leaves were able to increase the immune response of tiger prawns infected with Vibrio harveyi. This was indicated by the increase in total haemocyte count (THC), phenoloxidase (PO) and survival rate with the values of 0.05 × 106 cells / mL, 0.05 and 84 %, respectively, for the formulated diet treatment with 1500 mg/kg feed. The increase in tiger prawn immune response led to increased resilience against Vibrio harveyi. As a result, survival rates of treated tiger prawns were higher than the control.

Water Pretreatment Affects the Bacteria Communities in Penaeus monodon Larvae Culture

Water Pretreatment Affects the Bacteria Communities in Penaeus monodon Larvae Culture

Critical better management practices and critical bio-security measures for prevention of entry and spread of white spot virus and pathogenic Vibrio in grow-out farms of cultured Penaeus monodon in Sri Lanka

Since the first record of white spot disease (WSD) in 1996, PCR tested, white spot virus (WSV) free post larvae of Penaeus monodon (Fabricius 1798) are stocked in grow-out farms as the major bio-security measure. However, significantly high mortality in young shrimp and total rejection of harvest have been recorded in North Western Province, Sri Lanka due to WSD and/or vibriosis. Present study was planned to identify critical better management practices (CBMPs) and critical bio-security measures (CBSMs) that should be strictly adopted to prevent the entry and spread of WSV and pathogenic Vibrio in grow-out farms of P. monodon. A questionnaire survey, carried out at randomly selected 100 grow-out farms located in the North Western Province, revealed that there was a relationship between the occurrence of WSD and /or vibriosis and levels of practicing better management practices (BMPs) and/or bio-security measures (BSMs). Proper pre-stocking pond preparation, adoption of zero water exchange, monitoring and controlling water quality parameters including pathogenic Vibrio in culture water and use of a suitable bioaugmenter and a probiotic were identified as the CBMPs while proper disinfection of culture water, stocking of WSV and MBV free post larvae and prevention of WSV contamination through other routes over the rearing period were the identified CBSMs. Entry and spread of WSV and pathogenic Vibrio in P. monodon grow-out farms in the North Western Province, Sri Lanka could be prevented by strict adoption of CBMPs and CBSMs identified during the present study.

Effect of probiotic encapsulated Artemia Nauplii on the digestive enzyme activity in post larvae of Penaeus Monodon

Effect of probiotic encapsulated Artemia Nauplii on the digestive enzyme activity in post larvae of Penaeus Monodon

Response of post larvae ofPenaeus monodon (Fabricius, 1798) to varying temperatures

Response of post larvae ofPenaeus monodon (Fabricius, 1798) to varying temperatures

Efficacy of potential phage cocktails against Vibrio harveyi and closely related Vibrio species isolated from shrimp aquaculture environment in the south east coast of India

A diverse set of novel phages infecting the marine pathogenic Vibrio harveyi was isolated from shrimp aquaculture environments in the south east coast of India. Based on initial screening, three phages with a broad host range revealed that the growth inhibition of phage is relatively specific to V. harveyi. They were also able to infect V. alginolyticus and V. parahemolyticus that belonged to the Harveyi clade species from shrimp pond and sea coast environment samples. However, the impact of these phages on their host bacterium are well understood; a one-step growth curve experiment and transmission electron microscope (TEM) revealed three phages grouped under the Myoviridae (VHM1 and VHM2); Siphoviridae (VHS1) family. These phages were further molecular characterized with respect to phage genomic DNA isolates. The randomly amplified polymorphic DNA (RAPD), restriction fragment length polymorphism (RFLP) digestion with HindIII, and major structural proteins were distinguished by sodium-dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE) clearly indicated that all the phage isolates were different, even when they came from the same source, giving an insight into the diversity of phages. Evaluation of microcosm studies of Penaeus monodon larvae infected with V. harveyi (105 CFU mL−1) showed that larvae survival after 96 h in the presence of phage treatment at 109 PFU mL−1 was enhanced when compared with the control. The resolution in over survival highly recommended that this study provides the phage-based therapy which could be an innovative and eco-friendly solution against Vibrio disease in shrimp aquaculture and in the natural environment.

Transferable chloramphenicol resistance determinant in luminous Vibrio harveyi from penaeid shrimp Penaeus monodon larvae

Antibiotic-resistant luminous Vibrio harveyi strains isolated from Penaeus monodon larvae were screened for the possession of transferable resistance determinants. All the strains were resistant to chloramphenicol and the determinant coding for chloramphenicol resistance was transferred to Escherichia coli at frequencies of 9.50x10-4 to 4.20x10-4. The results probably suggest the excessive use of chloramphenicol in shrimp hatcheries to combat luminous vibriosis.

Transferable chloramphenicol resistance determinant in luminous Vibrio harveyi from penaeid shrimp Penaeus monodon larvae

Antibiotic-resistant luminous Vibrio harveyi strains isolated from Penaeus monodon larvae were screened for the possession of transferable resistance determinants. All the strains were resistant to chloramphenicol and the determinant coding for chloramphenicol resistance was transferred to Escherichia coli at frequencies of 9.50x10-4 to 4.20x10-4. The results probably suggest the excessive use of chloramphenicol in shrimp hatcheries to combat luminous vibriosis.

In vitro and in vivo inhibition of Ca2+-Mg2+-ATPase activity by cadmium in post larvae of Penaeus monodon

Ca2+-Mg2+-ATPase is a membrane-bound enzyme and is responsible for regulating cytosolic free calcium. In vitro and in vivo effects of cadmium were studied on Ca2+-Mg2+-ATPase activity in plasma membrane/mitochondrial fraction of Penaeus monodon post larvae. In vitro studies revealed a concentration-dependent decrease in enzyme activity with an IC50 value of 11.02 µM. In vivo experiments were conducted by exposing the post larvae to 1/10th (0.12 ppm) and 1/5th (0.24 ppm) of LC50 values of cadmium for 30 days. Both ATPase activity and metal accumulation were estimated in post larvae exposed to 0.12 and 0.24 ppm of cadmium at different intervals of 24 h, 48 h, 96 h, 10 days and 30 days. ATPase activity showed a gradual decrease in post larvae on exposure to both the sub-lethal concentrations with respect to their controls and the decrease was significant (p < .05) from 96 h onwards in post larvae exposed to 0.24 ppm and 10 days onwards on exposure to 0.12 ppm of cadmium. However, the effect of cadmium was higher in 1/5th than 1/10th sub-lethal concentration and also time-dependent. These enzyme studies were found to correlate with metal accumulation in post larvae at both the exposure concentrations. Disruption of calcium homeostasis might be one of the possible mechanisms of cadmium toxicity in these organisms.

Screening of probiotics bacteria from coral reef using co-culture method for controlling vibriosis in tiger shrimp (Penaeus monodon) larvae

&lt;p&gt;ABSTRACT&lt;/p&gt;&lt;p&gt;&lt;br /&gt;This study was carried out to obtain bacteria isolates from coral reef using co-culture method which potentially inhibit Vibrio harveyi growth. A total of 110 isolates were isolated from Acropora sp., Merulina sp., Hystrix sp., Poecillophora sp., Porites sp., and Haliophora sp., and were screened for their antagonistic activity against V. harveyi in in vitro and in vivo test. Five candidate probiotics (5H1 candidate probiotics isolated from Acropora sp., 11I and 11G isolates isolated from Hystrix sp. and 13B and 13G1 isolates isolated from Poecillophora sp., was able to inhibit growth of V. harveyi MR5339 RFR up to 101‒102 cfu/mL. Two isolates (13B and 13G1) were not pathogenic at concentration 106 cfu/mL bacteria and could increase of survival rate of tiger shrimp (Penaeus monodon) larvae in in vivo test. Survival rate of tiger shrimp larvae that treatment with 13B and 13G1 were 86,67% and 88,33%, and have a significant different with positive control (61,67%). Partial sequencing of 16S-rRNA showed that 13G1 isolate was similar to V. alginolyticus.&lt;br /&gt;Keywords: vibriosis, Vibrio harveyi, tiger shrimp, probiotic, coral reef&lt;/p&gt;&lt;p&gt;&lt;br /&gt;ABSTRAK&lt;/p&gt;&lt;p&gt;&lt;br /&gt;Penelitian ini bertujuan untuk mendapatkan bakteri probiotik asal terumbu karang dengan metode kultur bersama untuk pengendalian penyakit vibriosis pada larva udang windu (Penaeus monodon). Sebanyak 110 isolat berhasil diisolasi dari Acropora sp., Merulina sp., Hystrix sp., Poecillophora sp., Porites sp., dan Heliophora sp. dan dilakukan penapisan untuk melihat aktivitas kemampuannya melawan Vibrio harveyi MR 5339 RfR dalam uji in vitro dan in vivo. Sebanyak 56 isolat menghasilkan daya hambat terhadap V. harveyi MR5339 RfR pada metode kultur bersama. Lima isolat kandidat probiotik (isolate 5H1 diisolasi dari Acropora sp., isolat 11I dan 11G diisolasi dari Hystrix sp., serta isolat 13B dan 13G1 yang diisolasi dari Poecillophora sp.), mampu menekan pertumbuhan V. harveyi MR5339 RfR hingga 101–102 cfu/mL. Kedua isolat (13B dan 13G1) terbukti tidak bersifat patogen pada konsentrasi 106 cfu/mL dan mampu meningkatkan sintasan larva udang windu pada uji in vivo. Nilai sintasan larva pada perlakuan yang diberi kandidat probiotik 13B dan 13G1 berturut-turut adalah 86,67% dan 88,33%, namun berbeda nyata dengan kontrol positif (61,67%). Hasil analisis sekuen sebagian gen 16S-rRNA menunjukkan bahwa isolat 13G1 termasuk spesies V. algynoliticus.&lt;br /&gt;&lt;br /&gt;Kata kunci: vibriosis, Vibrio harveyi, udang windu, probiotik, terumbu karang&lt;/p&gt;

In vitro and in vivo study of acyl homoserine lactone degrading Bacillus against Vibrio harveyi

Vibriosis caused by Vibrio harveyi is still a bottleneck for the development of shrimp culture industry. As quorum sensing (QS) regulates the virulence of V. harveyi, interference of QS might offer opportunity for controling V. harveyi in shrimp culture. The aim of this study was to evaluate the ability of AHL-degrading Bacillus to interfere with the AHL production and the growth of V. harveyi in vitro and in vivo on Penaeus monodon larvae. Based on biochemical and molecular study, the AHL-degrading Bacillus was confirmed as B. subtilis STC. The results showed that AHL-degrading Bacillus affected (P 0.05) in all treatments. Yet, there was a trend that the higher of B. subtilis STC given, the smaller number of AHL available in the system. The survival rates of P. monodon larvae were significantly different (P<0.05) among treatments. The use of AHL-degrading bacteria, B. subtilis STC, at the concentration of 1x106 CFU.ml-1 improved the survival rate of P. monodon larvae up to 65.56% when infected by V. harveyi. Therefore, this AHL-degrading bacteria could be used as biocontrol agent against vibriosis in P. monodon larvae culture.

Carotenoid as a sensitive indicator of sub lethal cadmium toxicity in Penaeus monodon post larvae.

The objective of the present study is to evaluate a sensitive indicator of cadmium by measuring oxygen consumption and carotenoid concentration in post larvae of Penaeus monodon. The post larvae of P. monodon were exposed to 0.12 and 0.24mg/L of cadmium in the laboratory for a period of 30days. These concentrations represent 1/10th and 1/5th of 96h LC50 value for the post larvae. Oxygen consumption and carotenoid concentration were measured at 24, 48, 96h, 10 and 30days of cadmium exposure. The results indicated an inhibition of routine oxygen consumption in post larvae at different intervals of exposure from 24h to 30days but the effect was statistically significant (P<05) at 30days of exposure at both sub lethal concentrations, where the inhibition was 38.5% at 0.24mg/L and 21.6% at 0.12mg/L. On the other hand, carotenoid concentrations increased gradually with increasing period of exposure as well as concentration, and this increase was statistically significant (P<0.05) from 96h onwards on exposure to 0.12mg/L and from 48h onwards on exposure to 0.24mg/L of cadmium, with an overall highest increase of 135%. As carotenoid content is an indicator of tissue oxygen, inhibition of routine oxygen consumption might have resulted in enhancing the levels of carotenoid. From the present data, it is evident that carotenoid concentration can be considered as a sensitive indicator of cadmium toxicity than routine oxygen consumption in the post larvae of P. monodon. The present investigation is also relevant for environmental monitoring of cadmium in coastal waters before it is used for aquaculture.

English

There has been augmented curiosity in the application of herbal products against diseases causing marine pathogenic bacteria&nbsp;in aquaculture system. This paper describes antagonism of different types of garlic extract on the growth&nbsp;of Vibrio harveyithat produces luciferase, virulence and bio-luminescence.&nbsp;Aqueous filtered garlic extract (AFGE) showed zone of inhibition (12.33 &plusmn; 0.50 mm) against&nbsp;V. harveyi.&nbsp;But aqueous unfiltered garlic extract (AUGE) showed less zone of inhibition.&nbsp;V. harveyi&nbsp;treated with AFGE showed reduced growth varying from 0.32 to 0.26 OD as compared to the control. UV treated AFGE showed 9.0 &plusmn; 0.50 mm zone of inhibition against&nbsp;V. harveyi.&nbsp;But during heat treatment at 100 and 121&deg;C, the extracts lost their activity. Most of the virulence factors exhibited by&nbsp;V. harveyi&nbsp;were found to be reduced by AFGE treatment. Crude bacteriocin values changed from 0.10 to 0.24 OD as compared to the control (1.60 OD) for the 5 days. The cellular luciferase level was reduced to 86, 98, 79 and 94 counts per second (CPS, that is, photons/second) and the different CPS values are 23, 06, 12, 12 compared to the control. AFGE treatment also reduced bio-luminescence counts (30, 29, 35 and 30 CPS) with the differences being 14, 07, 09, 06. Challenge experiment proved that AFGE used in treating post larvae of&nbsp;Penaeus monodon&nbsp;showed less cumulative percentage mortality. In the control, maximum mortality of 2 - 42% occurred for 30 days. But in the AFGE treatment, mortality varied from 0.5 to 5.5%. Therefore, garlic extract may be a source of herbal product for controlling bacterial diseases in aquaculture. &nbsp; Key words:&nbsp;Garlic extracts,&nbsp;Vibrio harveyi, virulence factors, bio-luminescence, luciferase,&nbsp;P. monodon&nbsp;larviculture.