Parasites and diseases of fish cultured in the tropics , Parasites and diseases of fish cultured in the tropics , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Parasites and diseases of fish cultured in the tropics / Z. Kabata

The search for sustainable alternatives to synthetic herbicides for weed control, has led the scientific community to an increased interest for plant allelopathic mechanisms. The utilisation of plant extracts as possible bioherbicides represents an important solution. In the present study, laboratory experiments were carried out to investigate, for the first time, the differences in the allelopathic activity of the three Cynara cardunculus L. botanical varieties (globe artichoke, cultivated and wild cardoon) leaf aqueous extracts on the seedling growth of Amaranthus retroflexus L. and Portulaca oleracea L. In addition, the autoallelopathic effect on wild cardoon growth and the qualitative profile of the aqueous extract through high-performance liquid chromatograpy (HPLC) analysis were evaluated. Overall, the allelopathic effects were both genotype- and weed species-dependent. Wild cardoon showed the highest allelopathic potential (–23.4%), followed by cultivated cardoon and globe artichoke, and P. oleracea was the most sensitive target species (–32%). Besides, root system length was the most affected parameter (–32.6%). The autoallelopathic effect of wild cardoon extract was also demonstrated on root system length, hypocotyl and epicotyl length and total dry weight. C. cardunculus leaf aqueous extract was characterised by 5 sesquiterpene lactones, 2 caffeoylquinic acids, 6 flavones and 1 lignan. From the HPLC analysis we found that apigenin and luteolin 7-Oglucoronide were detected only in wild cardoon, apigenin 7-Oglucoside was typic of globe artichoke, and 11,13-dihydro-deacylcynaropicrin and 11,13-dihydroxi-8-deoxygrosheimin were characteristics of cultivated cardoon.

Allelopathic potential of leaf aqueous extracts from Cynara cardunculus L. on the seedling growth of two cosmopolitan weed species

National reviews for aquaculture development in Africa. 3: Sierra Leone

Background:  Many alien plant species, such as  Tithonia diversifolia, T. rotundifolia  and  T. tubaeformis , have been introduced to areas outside of their natural distribution range to provide benefits, but have subsequently become invasive, threatening biodiversity and agricultural productivity. Objectives:  The aim of this study was to determine the current distribution and dates of introduction of invasive  Tithonia  species in eastern and southern Africa and to document the effects of  T. diversifolia  on rural livelihoods in Zambia. Method:  Roadside surveys, and other sources of information, were used to determine the distribution of invasive  Tithonia  species in eastern and southern Africa. Household interviews were conducted to gauge perceptions and understand the impacts of  T. diversifolia  on local livelihoods in Zambia’s Copperbelt province. Results: Tithonia diversifolia  is widespread in Uganda, Kenya, Tanzania, South Africa, Malawi and parts of Zambia but less so in Zimbabwe.  Tithonia rotundifolia  was comparatively uncommon in eastern Africa but common in some southern African countries, while  T. tubaeformis  was invasive in Swaziland, South Africa, Zambia and possibly also Zimbabwe. According to the majority of respondents in Zambia,  T. diversifolia  has negative impacts on native vegetation, mobility or access, water availability, crop yields and animal health. Conclusion:  Invasive  Tithonia  species are widespread and spreading throughout much of Africa. Livelihood and biodiversity costs have not been considered by those actively promoting the use and further dissemination of  T. diversifolia . We therefore recommend that detailed cost–benefit studies should be undertaken to support informed decisions on the future management of these species.

/pdf/distribution-of-invasive-alien-tithonia-asteraceae-species-3l46x8swun.pdf

Distribution of invasive alien Tithonia (Asteraceae) species in eastern and southern Africa and the socio-ecological impacts of T. diversifolia in Zambia

Background: Antibiotics may be used in fish farms to prevent or treat bacterial infections especially in hatcheries. This affects a wide range of bacteria and has potential impact on receiving water bodies and fish pathogens and has been reported to contribute to antibiotic resistance in other parts of the world but there is no available report from Ghana. Aim: This study was carried out to assess some fish farming practices among catfish and tilapia farmers which may contribute to antibiotic resistance. Method: Validated questionnaires were administered to 63 fish farmers and 9 fishery officers in six zones of the Ministry of Fisheries, Ashanti Region of Ghana. Results/Findings: Seventy three percent of farmers claimed not to use antibiotics on their farms. Three farmers (4.8%) used tetracycline on the fish farms whilst two hatchery farmers add antibiotics (tetracycline or chloramphenicol) to fish feed. 93.6% of respondents who use manure on fish farms use poultry manure from commercial poultry farms and use it mainly to fertilize fish ponds. Conclusion: Most of the fish farmers interviewed do not use antibiotics on fish farms, practices such as manure use and untreated waste disposal may contribute to antibiotic resistance on fish farms in Ghana.

/pdf/antibiotic-use-and-practices-in-selected-fish-farms-in-the-4wpkgy0xn1.pdf

Antibiotic Use And Practices In Selected Fish Farms In The Ashanti Region Of Ghana

Allelopathic activities of some weeds in the Asteraceae family.

Effect of Chromolaena odorata on the Growth and Biomass Accumulation of Celosia argentea

Bacteria flora of Clarias gariepinus collected from two natural habitats namely Owena River (freshwater) and Igbokoda lagoon (brackish water) were examined using standard microbiological procedures. Thirteen bacterial species were identified. The result indicated that from the identified bacteria isolated, Vibrio sp, Proteus sp. Shigella sp. and E. coli were present in both habitats (fresh and brackish waters). Others were habitatselective such as Salmonella sp., Pseudomonas sp, Enterococcus sp, Staphylococcus sp. that were found only in freshwater habitat. While Branhamella sp, Streptococcus sp. and Micrococcus sp. were found in brackish water habitat. Bacteria load from Owena river (freshwater) was found to be the highest load recorded at 6.21 x 10cfu. T-test analysis also revealed that there was a marked significant difference between bacterial load in guts of sampled Clarias from fresh water and brackish water habitats. Keywords—Bacteria flora, gut, Clarias gariepinus, Owena river.

Bacteria Flora in the Gut and Respiratory Organs of Clarias gariepinus in Fresh and Brackish Water Habitats of Ondo State, South/West Nigeria

Introduction: Tilapias (Family Cichlidae) are among the freshwater fish species suitable for aquaculture and widely cultivated globally because of their fast growth rate, efficient use of natural aquatic foods, propensity to consume a variety of supplementary feeds, omnivorous feeding habits, resistance to disease and handling, ease of reproduction in captivity, and tolerance to wide ranges of environmental conditions Aims: Experiment was conducted to evaluate the growth performance of Oreochromis niloticus fed varying levels of Basella alba leave based diets. Materials and Methods: O. niloticus fingerlings (1.95±0.01g) were randomly selected and distributed into 15 glass tanks at the rate of 15 fish per tank representing five treatments and three replicates. Five diets were formulated to containing (0, 1.0, 1.5, 2.0 and 2.5 g/100kg diets) of B. alba were prepared and fed to the fish for 70 days. Results: The results revealed that weight gain, specific growth rate, feed intake and feed conversion ratio improved progressively up to the inclusion level of 2.0 g/100g of B. alba leave meal and then declined indicating 2.0g/100g B. alba leave meal as the optimum level that can promote the growth performance of the fish. However, 4th degree polynomial regression analysis indicated the optimum level as about 2.1 g/100g diet. It was observed that there was no significant difference in the survival (p > 0.05) of the fish fed diets with different B. alba leave meal. Conclusion: Based on the results obtained from this present study, it could be concluded that 2.0-2.1 g/100kg of B. alba leave can be included in the diets of O. niloticus fingerlings for optimum growth performance.

/pdf/effect-of-basella-alba-on-growth-performance-of-nile-tilapia-3ijk39yx0d.pdf

EFFECT OF BASELLA ALBA ON GROWTH PERFORMANCE OF NILE TILAPIA (Oreochromis niloticus) FINGERLINGS.

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Allelopathic activities of some weeds in the Asteraceae family.

Effect of Chromolaena odorata on the Growth and Biomass Accumulation of Celosia argentea

Bacteria Flora in the Gut and Respiratory Organs of Clarias gariepinus in Fresh and Brackish Water Habitats of Ondo State, South/West Nigeria

EFFECT OF BASELLA ALBA ON GROWTH PERFORMANCE OF NILE TILAPIA (Oreochromis niloticus) FINGERLINGS.