Strategies to reduce disease incidence in mud crab culture
Share
Abstract
Mud crab hatchery suffers from low survival due to susceptibility to bacterial infection in the early larval stages among many causes. Despite food safety issues, antibiotics continue to be used in the absence of effective alternatives. In this study, screening of plant extracts was conducted to determine their suitability as antimicrobial agents against pathogens causing low survival in the hatchery. In addition, potential probionts were isolated from the gastrointestinal tract of mud crab, and water and sediments of mud crab grow-out ponds.Crude ethanolic extracts from various terrestrial and mangrove trees were tested for in vitro antimicrobial activity and toxicity to mud crab zoea and megalopa. In addition, the in vivo antimicrobial efficacies of the selected extracts were tested by oral administration followed by experimental challenge with Vibrio harveryi. On the other hand, the putative probionts, were tested for pathogenicity against mud crab zoea and megalopa and quorum sensing inhibition activity against V. harveyi. Finally the extracts and probionts were tested for their efficacy in simulated hatchery and grow-out trials.Results showed that extracts of Terminalia cattapa and the potential probiont Bacillus subtilis G100R11 showed antimicrobial and probiotic activity in in vitro and in vivo tests. In simulated hatchery trials, T. cattapa administration successfully produced crab instar with a survival of 1.3-1.8% in trials 1 and 2 comparable to antibiotic control. B. subtilis produced crab instar with survival of 0.8-1.0% in trials 1 and 2, better than the commercial probiotic with 0-0.13% survival. Using T. cattapa and B. subtilis, survival was above 30% until zoea 5 but suddenly dropped below 5% during metamorphosis to megalopa where high incidence of incomplete molting was observed. If difficulty affecting the molting process is addressed, high survival from zoea to megalopa and crab instar will be achievable.
Description
Abstract only.
Suggested Citation
Amar, E. C., Somera, M. D., Madero, S. B., Tendencia, E. A., & Faisan Jr., J. P. (2017). Strategies to reduce disease incidence in mud crab culture. In E. T. Quinitio, F. D. Parado-Estepa, & R. M. Coloso (Eds.), Philippines : In the forefront of the mud crab industry development : proceedings of the 1st National Mud Crab Congress, 16-18 November 2015, Iloilo City, Philippines (p. 154). Tigbauan, Iloilo, Philippines: Aquaculture Department, Southeast Asian Fisheries Development Center.
Type
Conference paperISBN
9789719931072Collections
Related items
Showing items related by title, author, creator and subject.
-
Country status of aquatic emergency preparedness and response systems for effective management of aquatic animal disease outbreaks in Myanmar
(Aquaculture Department, Southeast Asian Fisheries Development Center, 2019)Myanmar is one of the OIE members and the Department of Fisheries (DoF) is highly concerned with transboundary aquatic animal pathogens. Therefore, the Aquatic Animal Health & Disease Control Section has already been formed not only for field diagnostic surveys but also for border control especially at international airport and border trade areas by checking and counter checking export and import of aquatic animals and products. At the moment, the DoF is stressing an issue of some transboundary diseases for finfish such as Gyrodactylus sp., Dactylogyrus sp., Argulus sp., Trichodena sp., Streptococcus sp., Aeromonas sp., and for crustacean are MrNV/XSV and WSSV. In addition, the DoF is facing challenges with parasitic disease and bacterial disease problems due to poor water quality management at culturing fish ponds. For the prevention and control of fish diseases within the country, the DoF is issuing Health Certificates by physical and microbiological examination of fishes and fisheries products. At the same time, Quarterly report on fish disease has being regularly submitted to NACA, OIE since 1998 until now. Although the DoF has no specific law and legislation on the control of quarantine pest and disease of aquatic animal, a good aquaculture practice has been implemented and code of conduct responsible for aquaculture is being followed in the country. The aquatic health management is a challenging issue in aquaculture development. Myanmar is still needing technical assistance to improve quarantine system especially for importation and exportation of live aquatic animals. Moreover, monitoring and surveillance programs with harmonized aquatic emergency preparedness and response system are required to boost up not only for Myanmar but also for effective management of transboundary disease outbreaks in Southeast Asia. -
Transboundary aquatic animal diseases: History and impacts in ASEAN aquaculture
(Aquaculture Department, Southeast Asian Fisheries Development Center, 2019)Aquaculture is one of the important sectors in the economy of most Asia-Pacific countries. However, majority of aquaculture farms are small-scale and most often lack the necessary facilities to comply with or are not well informed of the product standards imposed by concerned authorities, especially for international trade. Most countries in the region have a high reliance on aquatic animals as the major source of protein for their populations. In the past 20 years, farming of shrimp and fish for export has become a major employer and revenue earner for many countries in the region. Aquaculture is a major employer, contributes significantly to national economies, assists in poverty reduction, and is an important element in food security and other national development priorities. Aquaculture has developed rapidly in the region and is now a significant component in the national economies of many countries. However, recent disease events in fish and shrimp farming have indicated that preparedness and response measures are lacking, contributing to spread of disease across large areas of the countries involved. The growth of aquaculture in recent decades has been dependent on the international movement of aquatic animals and, in particular, the introduction of non-native species. The movement of live aquatic animals and their products has the potential to spread pathogens from one country or region to another, which may result to disease outbreaks. In shrimps as example, most major disease outbreaks were associated with the movement of live animals (broodstock, nauplii and postlarvae) when the patterns of disease spread were analyzed. Many aquatic animal diseases, once established, are often difficult to treat or to eliminate. Over the past 30 years, the Asia-Pacific region has been swept by a number of devastating diseases of aquatic animals which have caused massive economic and social losses. These include spread and outbreaks of infection with Aphanomyces invadans (EUS) in freshwater fish, viral nervous necrosis (VNN) in marine fish, viral hemorrhagic septicaemia (VHS) in marine and freshwater fish, and several viral diseases in shrimps such as white spot disease (WSD), white tail disease (WTD), yellow head disease (YHD) and infectious myonecrosis (IMN) among others. This demonstrates the vulnerability of the aquaculture industry as well as the wild populations to disease emergence in the region. The impacts of these diseases have been aggravated by the lack of effective preparedness and response whenever diseases emerge. Although some national, regional and international actions towards disease emergencies have paved way to disease spread prevention in recent years (e.g. Acute hepatopancreatic necrosis diseases; AHPND), there are still several emerging diseases that need to be considered by aquaculture-producing countries, especially in the ASEAN, through a harmonized and effective emergency preparedness and disease response. -
Infectious diseases of warmwater fish in fresh water
(CABI Publishing, 2014)This chapter presents the viral, bacterial, pseudofungal and parasitic diseases in cultured warm freshwater fish. Focus is given on the distribution, causative agent, pathology, diagnosis, prevention and control of these diseases.
