Regional response on AHPND and other emerging shrimp diseases in the Asia-Pacific

Transboundary aquatic animal diseases are among the major concerns for establishing biosecurity measures and strengthening of aquatic animal health (AAH) management capacity (including emergency preparedness) in the region. In aquaculture, biosecurity and AAH management entails protection of fish or shellfish from infectious agents (viral, bacterial, fungal or parasitic) as well as prevention of disease spread from one area to another. Several transboundary aquatic animal diseases have swept the region over the past 25 years causing massive economic and social losses. These include spread and outbreaks of epizootic ulcerative syndrome (EUS) in freshwater fish, viral nervous necrosis (VNN) in marine fish, viral haemorrhagic septicaemia (VHS) in marine and freshwater fish, and several viral diseases in shrimps (e.g. white spot disease [WSD], infectious haematopoietic necrosis [IHHN]). The spread of these transboundary diseases clearly demonstrates the vulnerability of the aquaculture industry to disease emergence where impacts have been aggravated by the lack of effective preparedness and response when diseases emerge. Recently, outbreaks of acute hepatopancreatic necrosis disease (AHPND), popularly known as early mortality syndrome (EMS), among cultured shrimps were reported in China and Viet Nam (2010), Malaysia (2011), Thailand (2012), Mexico (2013) and the Philippines (2014). There have been reports of its spread in South American countries but limited report is available in this regard. This disease caused significant losses in the production of Penaeus monodon and P. vannamei in the affected countries. NACA s regional response to this disease during its initial outbreak in Viet Nam, Thailand and Malaysia signified that improved control on transboundary diseases and emergency preparedness are still needed in the region. In collaboration with international organizations (OIE, FAO), NACA has implemented awareness programs, efficient information dissemination, and emergency regional expert consultation to address this disease problem. OIE and FAO also deployed experts to assess the disease and identify the pathogen involved. All of these efforts, together with subsequent studies on prevention and disease management, have paved the way in preventing further spread of this disease to other shrimp-producing countries so far. However, the risk is still very high that this disease will spread, as transboundary movement of live shrimps within and outside the region is inevitable. In addition, other emerging diseases are now affecting production of major cultured shrimps in the region. These include hepatopancreatic microsporidiosis (HPM) caused by Enterocytozoon hepatopenaei (EHP) with confirmed reports from China, Viet Nam, Thailand, Malaysia and Indonesia (unconfirmed reports from India), and viral covert mortality disease (VCMD) which was reported to be affecting cultured shrimps in China. By and large, outbreaks of damaging aquatic animal diseases are likely to continue and the potential consequences are likely to increase with the expansion (intensification) of aquaculture systems and introduction of new species for culture. Consequently, the risks associated with emerging and transboundary diseases are shared - shared water bodies and epidemiological links through trade (especially live movement) - thus, a collaborative approach in dealing with these diseases is therefore warranted and necessary

Fast demographic traits promote high diversification rates of Amazonian trees

The Amazon rain forest sustains the world's highest tree diversity, but it remains unclear why some clades of trees are hyperdiverse, whereas others are not. Using dated phylogenies, estimates of current species richness and trait and demographic data from a large network of forest plots, we show that fast demographic traits - short turnover times - are associated with high diversification rates across 51 clades of canopy trees. This relationship is robust to assuming that diversification rates are either constant or decline over time, and occurs in a wide range of Neotropical tree lineages. This finding reveals the crucial role of intrinsic, ecological variation among clades for understanding the origin of the remarkable diversity of Amazonian trees and forests

Fungal diseases

Over the past 20 years, aquatic animal mycopathogens have become the focus of considerable research. The many known occurrences of fungal diseases in wild populations and the documented devastating disease outbreaks indicate that fungal and fungal-like pathogens are important in nature. Fungal diseases can act as major limitations on natural and cultured populations of aquatic animals. However, knowledge on fungal diseases is rudimentary consisting primarily of the identification and pathology of etiological agents. Detection of fungal infections relies only on the observation of gross pathology, histological examinations, and standard mycological isolation and identification procedures. As a result, there are some cases where the implicated fungal pathogen cannot be demonstrated as the primary cause of a particular disease. In such cases, the fungal pathogen is usually regarded as secondary invader. Continued research in basic mycology is still an essential resource for fish pathologists in diagnosing diseases caused by fungi. Although fungi reportedly affect very few species, fungal diseases, if not properly controlled or prevented, can still pose a threat to the aquaculture industry

Haliphthoros spp. from spawned eggs of captive mud crab, Scylla serrata, broodstocks

Monitoring of the fungal flora of spawned eggs of captive mud crab, Scylla serrata, was conducted in several hatchery runs at the Aquaculture Department of Southeast Asian Fisheries Development Center in Iloilo, Philippines. Quantification of the egg mycoflora revealed the dominance of oomycetes, particularly Haliphthoros spp. among spawners which aborted their eggs prior to hatching. Two species of Haliphthoros (H. philippinensis and H. milfordensis) were identified from the 24 isolates collected. Haliphthoros milfordensis was the dominant species. Physiological studies on vegetative growth and sporulation of the two species show that H. philippinensis have wider optimal range for salinity and temperature requirements than H. milfordensis, especially in sporulation. The pathogenicity study showed that only H. milfordensis was pathogenic to spawned eggs of S. serrata, while H. philippinensis was not. Infection of S. serrata eggs by H. milfordensis was observed starting at two days after inoculation of zoospores with 2-5% infection rate, reaching up to 10% at five days post-inoculation.Materials and culture media used in this study were obtained from SEAFDEC AQD funded study (study code Nr-05-F99T). The author thanks E. Borlongan for providing the mud crab egg samples used in this study, S.A. Pedrajas for technical assistance, and E. Quinitio for some information on the larval rearing of mud crabs

Transboundary aquatic animal diseases: History and impacts in ASEAN aquaculture

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

Ecology of straminipiles from mangrove habitats

Straminipiles are common inhabitants of marine, estuarine and freshwater aquatic environments. In mangrove habitats, halophytophthorans and thraustochytrids are abundant, both in tropical and sub-tropical areas. Their abundance is attributed to their wide tolerance to environmental parameters such as salinity and temperature, and their ability to produce abundant zoospores. Fallen mangrove leaves supply the bulk of organic material in any mangrove habitat. Straminipiles are one of the initial colonizers of fallen mangrove leaves. The ability of their zoospores to respond chemotactically to nutrients released by the leaves, and to attach firmly on the substrata surface by the release of adhesive materials, make them highly competitive in the colonization process. Thus, they are reported to play significant role in the microbial degradation of fallen mangrove leaves. Moreover, these organisms, especially thraustochytrids, are producers of high amounts polyunsaturated fatty acids (PUFAs). Therefore in the degradation process, they consequently enrich the nutrient content of the leaves for the benefit of other organisms at higher trophic levels, making mangroves an excellent nursery grounds for many fish and crustacean species. Some species of thraustochytrids are also used in the commercial production of PUFAs, for use in aquaculture specifically in larval rearing of marine fish and crustaceans

Fungal diseases

Over the past 20 years, aquatic animal mycopathogens have become the focus of considerable research. The many known occurrences of fungal diseases in wild populations and the documented devastating disease outbreaks indicate that fungal and fungal-like pathogens are important in nature. Fungal diseases can act as major limitations on natural and cultured populations of aquatic animals. However, knowledge on fungal diseases is rudimentary consisting primarily of the identification and pathology of etiological agents. Detection of fungal infections relies only on the observation of gross pathology, histological examinations, and standard mycological isolation and identification procedures. As a result, there are some cases where the implicated fungal pathogen cannot be demonstrated as the primary cause of a particular disease. In such cases, the fungal pathogen is usually regarded as secondary invader. Continued research in basic mycology is still an essential resource for fish pathologists in diagnosing diseases caused by fungi. Although fungi reportedly affect very few species, fungal diseases, if not properly controlled or prevented, can still pose a threat to the aquaculture industry

Straminipilous organisms from fallen mangrove leaves from Panay Island, Philippines

Fallen senescent mangrove leaves from three marine mangrove sites in Panay island, Philippines were collected for observation and isolation of straminipilous organisms. A total of 11 mangrove species were sampled. Halophytophthora species were observed on 7 out of 11 mangrove species sampled, with H. vesicula as the most abundant species observed. Halphytophthora epistomium also occurred abudantly on fallen leaves of Rhizophora apiculata and Sonneratia sp. Thraustochytrids, on the other hand, were observed on all mangrove leaf samples except Aegiceras corniculatum. Schizochytrium mangrovei was the most abundant species observed. Their association and ecological role on the degradation of fallen mangrove leaves is discussed.This study was funded by SEAFDEC/AQD under study code Nr-05-F99T

Toxicity of four botanical insecticides to fingerlings of Nile tilapia and common carp

Static bioassay test was done to determine the toxicity of four botanical insecticides (BI) - Blumea balsamifera leaves, Vitex negundo leaces, Azadirachta indica seeds, Tinospora rumphii stems to fingerlings (0.8 - 1.5g) nile tilapia (Oreochromis niloticus) and common carp (Cyprinus carpio). Median lethal concentration (g/1) obtained at 96 - hour of exposure for O. niloticus and C. carpio, respectively, were 1.54 and 137 (B. balsamifera), 4.95 and 3.53 (V. negundo), 1.59 and 0.55 (A.indica), and, 0.77 and 2.13 (T. rumphii). Analysis on the levels of toxicity of each BI showed that A. indica was the most toxic to O. niloticus to C. carpio, at 24 - h of exposure. At 96 - h, however, B. balsamifera and T. rumphii appeared to be the most toxic to O. niloticus while T. rumphii to C. carpio. V. negundo was the least toxic to both test species. Results of this study could be used as basis for field application rates of the test botanicals as piscicide in ponds and as insecticide in pest management rice-fish farming

Important diseases of Penaeid shrimps

In tropical Asia, the two main species of penaeid shrimps that are widely cultured are the black tiger shrimp (Penaeus monodon) and the Pacific white shrimp (Penaeus (Litopenaeus) vannamei). The former species is indigenous in most Asian countries while the latter is indigenous in the Americas and was introduced to Asian countries in the late 1990s. In this chapter, only details of the economically-important microbial infections in Asia in these two penaeid shrimps are presented and arbitrarily grouped as viral, bacterial, fungal and parasitic diseases. Viral infections are divided further into two groups: DNA viruses; and, RNA viruses. The infections attributed to DNA viruses are: White Spot Disease (WSD) Disease, Penaeus stylirostris densovirus (PstDNV) previously known as Infectious Hypodermal and Hematopoietic Necrosis Virus (IHHNV) Disease, Penaeus monodon densovirus (PmDNV) formerly known as Hepatopancreatic Parvo-like Virus (HPV) Disease and Penaeus monodon nucleopoly-hedrovirus (PemoNPV) previously known as Monodon Baculovirus (MBV) Disease. The shrimp infections caused by RNA viruses are: Yellow Head Virus (YHV) Disease, Taura Syndrome Virus (TSV) Disease, and Infectious Myonecrosis Virus (IMNV) Disease. For bacterial diseases, the list includes Luminous Bacterial Disease, Non-luminous Vibrio Infections, and Acute Hepatopancreatic Necrosis Disease (AHPND). Fungal disease includes Larval mycosis, while parasitic disease includes the current emerging threat to the shrimp industry, the Hepatopancreatic Microsporidiosis caused by Enterocytozoon hepatopenaei (EHP)