Browsing by Author "de la Peña, Leobert D."
Book chapterEV Alapide-Tendencia & LD de la Peña - In GD Lio-Po, CR Lavilla & ER Cruz-Lacierda (Eds.), Health Management in Aquaculture, 2001 - Aquaculture Department, Southeast Asian Fisheries Development CenterFish and crustaceans that are not weakened by poor environmental conditions, or by other causes, such as parasitic infestation, nutritional deficiency, handling stress, or chemical intoxication, are more resistant to bacterial infections. This is due to the presence of a large amount of bactericidal substances in the blood, which helps overcome infections. So, the best precaution against the occurrence of bacterial infections is to provide the fish with optimum environmental conditions, adequate amounts of the right kinds of food and avoidance of stress, including overcrowding. Vaccination/ immunization and genetic manipulation (i.e., the development of specific pathogen resistant fry) are also some ways of preventing bacterial diseases. The use of antibiotics should always be an option of the last resort.
Development of farming schemes following disease occurrences in monodon shrimp farming using intensive method in three Southeast Asian countries T Matsuura, LD de la Peña, CP Ean, R Siow & AH Alias - In T Matsuura (Ed.), Comparative Analysis of Aquaculture Management in Brackish Mangrove Areas in Three Southeast Asian Countries, 2007 - Japan International Research Center for Agricultural Sciences
Series: JIRCAS Working Report; No. 56All three countries experienced major progress in intensive shrimp farming at different ties. Intensive farming of monodon shrimp (Penaeus monodon, an indigenous species) was first launched by the Philippines, followed by Thailand, then by Peninsular Malaysia. The survey was conducted from 2000-2005. The disease-causing bacterial that seiously damaged monodon culture were luminous bacteria in the Philippines and white spot virus in Thailand and Malaysia. Production decreased because of these diseases in the mid-1990s in the Philippines and after 2000 in Thailand and Malaysia. In 1998, the Green Water System (hereinafter referred to as GWS) was developed, and a proportion of culture ponds introduced it and resumed monodon culture using the intensive method. In Thailand, the vannamei shrimp (Penaeus vannamei, an exotic species from South America) has now replaced monodon previously raised using the extensive method. In Malaysia, monodon is cultured using only the intensive method, and some culture pond enterprises started to culture vannamei instead of monodon in 2004. In the Philippines, companies engaging in monodon culture have many ponds and lower stocking density because they culture large-size shrimp, but are exposed to high running costs such as fuels and probiotics. On the other hand, in Thailand, individuals engaging in monodon culture have few ponds and higher stocking density since they culture small-scale shrimp. Labor costs are low because most of the work is done by family member.
Studies on the chemical control of luminous bacteria Vibrio harveyi and V. splendidus isolated from diseased Penaeus monodon larvae and rearing water MCL Baticados, CR Lavilla-Pitogo, ER Cruz-Lacierda, LD de la Peña & NA Suñaz -
Diseases of Aquatic Organisms, 1990 - Inter ResearchThe minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of 24 drugs for luminous bacteria Vibrio harveyi and V. splendidus were determined. Only chloramphenicol, sodium nifurstyrenate and the nitrofurans (furazolidone, nitrofurazone, nitrofurantoin and Prefuran) showed relatively low MICs and MBCs (<25 µg/ml-1). The bacteria showed varied responses to chloramphenicol and Prefuran and low sensitivity to oxytetracycline. Chloramphenicol, oxytetracycline and Prefuran are commonly used in shrimp hatcheries. Shrimp larvae showed high survival rates and active swimming movement after 24 h exposure to in vivo bactericidal doses of chloramphenicol, Furacin, nitrofurantoin (protozoa only), oxytetracycline (nauplius only), Prefuran (mysis only) and sodium nifurstyrenate, but the drugs caused deformities in the carapace, rostrum, and setae. Chemical control of luminous vibriosis among shrimp larvae appears limited, based on the efficacy of existing and readily available drugs, because of the possible development of resistant strains of bacteria and the limited tolerance of the shrimp larvae to the drugs.
Book chapterGD Lio-Po & LD de la Peña - In K Nagasawa & ER Cruz-Lacierda (Eds.), Diseases of cultured groupers, 2004 - Aquaculture Department, Southeast Asian Fisheries Development CenterSome viral infections are serious diseases of groupers causing heavy mortalities. In most cases, larval stages are the most susceptible stage. With the carnivorous nature of groupers, they can readily ingest viral pathogens from live fish food or trash fish that carry the viral pathogens. Moreover, viruses are able to effect vertical transmission from broodstocks that are likely carriers of the virus. Survivors of viral epizootics can be carriers of viral pathogens. This chapter focuses on current information on the major viral infections of groupers, i.e., viral nervous necrosis (VNN) and viral infections attributed to the family Iridoviridae.
Book chapter | Article
Viral nervous necrosis (VNN) as a critical infectious disease of orange-spotted grouper, Epinephelus coioides, in the Philippines I Kiryu, LD de la Peña, Y Yoshiura, M Ototake & Y Maeno - In K Nakamura (Ed.), Sustainable Production Systems of Aquatic Animals in Brackish Mangrove Areas, 2007 - Japan International Research Center for Agricultural SciencesOrange-spotted grouper, Epinephelus coioides, is a valuable commodity in the Philippines. In 2001, mass mortality occurred in the grouper larvae at Aquaculture Department, Southeast Asian Fisheries Development Center (SEAFDEC/AQD) and the disease was identified as viral nervous necrosis (VNN). Since then, the disease has been observed every year and the grouper hatcheries have been devastated. In this paper, recent studies of VNN which were conducted at the SEAFDEC/AQD from 2001 to 2006 are reviewed. 1) Susceptibility to the VNN virus was tested among fish species that were cultured in mangrove brackish are. Five representative cultured fish species including orange-spotted grouper, Asian sea bass (Lates calcarifer), mangrove red snapper (Lutjanus argentimaculatus), milkfish (Chanos chanos) and rabbitfish (Siganus guttatus) were used in the test where the virus was intraperitoneally injected into the juveniles. Although low or no mortality occurred in the challenge test, histopathological changes were observed in the brain and retina where the virus was re-isolated. The results were the same among the species except for rabbitfish which had no evidence for the infection. It was verified that the virus has a wide host range. 2) To estimate the possible risk of viral spread by vertical transmission, virus distribution was determined in asymptomatic groupers including 7 broodstock and 17 juveniles with body weights ranging from 4 to 12 kg and 2 to 9 respectively. The virus was detected by PCR method. The highest detection rate was in the brain, and the virus was also detectable in other organs such as the gills, heart, spleen, kidney, blood, esophagus, stomach, intestine, liver, gonad, swim bladder and/or skin. 3) As a possible VNN vaccine, a DNA p;asmid encoding the capsid protein of the virus was evaluated. After the challenge, the mortalities between the native and DNA-injected fish appeared significantly different (P<0.05).