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1.
Lett JM Granier M Hippolyte I Grondin M Royer M Blanc S Reynaud B Peterschmitt M 《Phytopathology》2002,92(1):65-74
ABSTRACT Spatial and temporal distribution of Maize streak virus (MSV, family Geminiviridae, genus Mastrevirus) was monitored in the vector species Cicadulina mbila and the nonvector species C. china? using conventional and real-time quantitative polymerase chain reaction. Sustained feeding on MSV-infected plants showed that virus accumulation reaches a maximum in C. china?, but not in C. mbila. After a 3-day acquisition access feeding period (AAP), MSV was detected in the gut, the hemolymph, and the head of C. mbila, but only in the gut of C. china?. Similarly, Digitaria streak virus (genus Mastrevirus), which is not transmitted by either of the two species, was only detected in the gut. MSV was detected in the hemolymph of C. mbila 3 h after the beginning of the AAP. Although viral DNA progressively decreases in the vector and nonvector species after a 3-day AAP, MSV DNA remained stable in the salivary glands of C. mbila. 相似文献
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Molia S Frebling M Vachiéry N Pinarello V Petitclerc M Rousteau A Martinez D Lefrançois T 《Veterinary parasitology》2008,153(3-4):338-346
We report Marie Galante as one of the Caribbean islands most heavily infested by the tropical bont tick (TBT) Amblyomma variegatum which is associated with two major diseases of ruminants: heartwater and dermatophilosis. In 2005, a survey was undertaken to assess the prevalence of TBT infestation in cattle, the prevalence of Ehrlichia ruminantium infection in TBTs, and the tick control measures implemented by livestock owners. A random sample of 195 cattle herds out of 1885 recorded on the island was investigated by thoroughly counting adult ticks on each animal and filling a questionnaire. A randomly collected sample of 136 TBTs was tested for infection by E. ruminantium by pCS20 nested PCR. Cattle herd prevalence (hp) was 73.8% for infestation by at least one TBT, 17.9% for infestation by at least one engorged female TBT, and 8.2% for clinical dermatophilosis. Cattle individual prevalence was 42.3% for infestation by at least one TBT, 6.6% for infestation by at least one engorged female TBT, and 2.2% for clinical dermatophilosis. The minimum, maximum and average numbers of TBTs per infested animal were, respectively 1, 108 and 11.5. Prevalence of TBT infection by E. ruminantium was 19.1%. No significant difference in herd prevalence was found among parishes or among ecological zones. For cattle owners treating against ticks (97.9% of all owners), all used aspersion of amitraz and herd prevalence was significantly different among those treating every 1-2-week (hp=69.6%, n=148), and less often than every 2-week (hp=88.6%, n=35) (P=0.031). Of the 42 herd subunits treated less than 4 days before the survey, 27 (64%) were infested with at least one TBT, and 6 (14%) with at least one engorged female TBT. These results indicate a high level of TBT infestation in Marie Galante, the inefficacy of tick treatments currently performed, and the need for an improved tick control strategy. Persisting high levels of infestation in Marie Galante threaten the success of on-going TBT eradication programs in the Caribbean because TBT can spread through migrating birds and trade of animals or of animal hides to other islands and potentially the American continent. 相似文献
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Serge‐Eric Monentcham Jean Kouam Didier Chuba Bernard Wathelet Victor Pouomogne Patrick Kestemont 《Aquaculture Research》2010,41(10):e385-e392
A feeding trial was conducted to examine the suitability of soybean meal (SBM) and cottonseed meal (CSM) as a partial substitute for the dietary protein supplied by fish meal for H. niloticus fingerlings. Fish were fed with four isonitrogenous (350 g kg?1 crude protein) and isoenergetic (18.8 kJ g?1 GE) diets in which fish meal protein was gradually replaced by plant protein from a mixture of SBM and CSM (0%, 25%, 50% and 75% in diets 1, 2, 3 and 4 respectively). Triplicate groups of fingerlings H. niloticus (mean weight of 5 g) were handfed twice daily to apparent satiation for 60 days inside net hapas. Growth performances (SGR varied from 3.09% to 3.16% day?1) of fingerlings fed diets containing 0%, 25% and 50% plant protein were not significantly different (P>0.05). At 75% fish meal substitution, growth and feed utilization efficiency indicators were significantly reduced (P<0.05). The carcass composition were also significantly (P<0.05) affected by the replacement level of fish meal, except dry matter and ash. Results suggest that the dietary fish meal protein could efficiently be substituted by a mixture of soybean and cottonseed meals up to 50%, without adverse effects on maximal growth in practical diets for H. niloticus fingerlings. 相似文献
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Christopher J. Fulton Charlotte Berkstrm Shaun K. Wilson Rene A. Abesamis Michael Bradley Carolina kerlund Luke T. Barrett Abner A. Bucol Dinorah H. Chacin Karen M. Chong‐Seng Darren J. Coker Martial Depczynski Linda Eggertsen Maria Eggertsen David Ellis Richard D. Evans Nicholas A. J. Graham Andrew S. Hoey Thomas H. Holmes Michel Kulbicki Priscilla T. Y. Leung Paul K. S. Lam Joshua van Lier Paloma A. Matis Mae M. Noble Alejandro Prez‐Matus Camilla Piggott Ben T. Radford Stina Tano Paul Tinkler 《Fish and Fisheries》2020,21(4):700-717
Canopy‐forming macroalgae can construct extensive meadow habitats in tropical seascapes occupied by fishes that span a diversity of taxa, life‐history stages and ecological roles. Our synthesis assessed whether these tropical macroalgal habitats have unique fish assemblages, provide fish nurseries and support local fisheries. We also applied a meta‐analysis of independent surveys across 23 tropical reef locations in 11 countries to examine how macroalgal canopy condition is related to the abundance of macroalgal‐associated fishes. Over 627 fish species were documented in tropical macroalgal meadows, with 218 of these taxa exhibiting higher local abundance within this habitat (cf. nearby coral reef) during at least one life‐history stage. Major overlap (40%–43%) in local fish species richness among macroalgal and seagrass or coral reef habitats suggest macroalgal meadows may provide an important habitat refuge. Moreover, the prominence of juvenile fishes suggests macroalgal meadows facilitate the triphasic life cycle of many fishes occupying diverse tropical seascapes. Correlations between macroalgal canopy structure and juvenile abundance suggests macroalgal habitat condition can influence levels of replenishment in tropical fish populations, including the majority of macroalgal‐associated fishes that are targeted by commercial, subsistence or recreational fisheries. While many macroalgal‐associated fishery species are of minor commercial value, their local importance for food and livelihood security can be substantial (e.g. up to 60% of landings in Kenyan reef fisheries). Given that macroalgal canopy condition can vary substantially with sea temperature, there is a high likelihood that climate change will impact macroalgal‐associated fish and fisheries. 相似文献
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Stephen Adu-Bredu Alphonse Foua Tape Bi Jean-Pierre Bouillet Martial Kouamé Mé Samuel Yamoah Kyei Laurent Saint-André 《Forest Ecology and Management》2008
Studies on stem profile of teak (Tectona grandis) hardly exist. This can be possibly attributed to the occurrence of forks that is prevalent on teak trees. Stem profile model was therefore developed for teak in West Africa, which took into account the occurrence of forks. Trees were destructively sampled from Moist Evergreen Forest (MEF), Moist Semi-deciduous Forest (MSDF), Dry Semi-deciduous Forest (DSDF) and Savannah ecological zones in both Ghana and Côte d’Ivoire for the study. A single set of parameters could be used explicitly to predict stem profile of any teak tree, irrespective of country, eco-climatic zone, edaphic variables, site index, tree age, stand density and tree competition. The model efficiency and root mean square error (in relative diameter) were calculated to be 0.97 and 0.053, respectively. The relative position of the forks along the stem bole, with respect to total tree height, was highly variable and did not follow any particular trend, except higher value for the first fork in the Moist Evergreen Forest zone. However, average tree height to the first fork decreased along the ecological gradient from MEF, MSDF and DSDF to Savannah. The extent of diameter reduction due to the forks could be predicted. Relative tree form for zero-forked, one-forked and two-forked trees was calculated to be 0.39, 0.36 and 0.33, respectively. Relative loss of stem volume due to one fork and two forks was estimated to be 6.5 and 13.9%, respectively. The measured stem volume when related to the corresponding predicted value yielded coefficient and intercept not significantly different from unity and zero, respectively, with an r2 value of 0.97. 相似文献
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Marc K. Kouam Manjeli Jacouba Inouss N. Nsangou Alexis Teguia 《Tropical animal health and production》2018,50(7):1529-1538
The recent outbreak of avian influenza in the poultry sector of Cameroon has raised a concern about the level of implementation of biosecurity measures (BM) on poultry farms. Therefore, a study using a questionnaire on 102 randomly selected poultry farms was undertaken. Some measures with high adoption levels (>?90%) included “protection of airing openings of poultry barns by a wire mesh,” “no external animal allowed to enter the farm,” “respect of all-in all-out principle,” “functional footbath,” “rodent control,” and “feedstuff protection from access to rodents.” The least implemented measures (less than 20%) were “wearing of dedicated clothing (clean coveralls and boots) by workers,” “disinfection of visitors,” and “presence of storage room for dead animals.” Only for “isolation” component of biosecurity, compliance with biosecurity measures was good, with more than 50% of farms having an adoption rate greater than 75%. The mean biosecurity score for the assessed farms was 19.29?±?1.89 for a maximum score of 38 points. The score was significantly and positively correlated (p?<?0.05) with the number of chicken and the geographic location of farms. The other results showed that the mean number of broiler per cycle was 550.82?±?76 for a stocking density of 27.20?±?6.64 birds per m2. In conclusion, broiler production in the Western highland is dominated by small-scale units with low level of biosecurity practices positively and significantly (p?<?0.05) influenced by some production characteristics. To improve biosecurity practices in the area, efforts must focus on measures concerning “sanitation” and “traffic control” components of biosecurity. 相似文献
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The African rice Oryza glaberrima, traditionally cultivated since more than 3.500 years, is of poor agronomic performance but resistant/tolerant to various
stresses and diseases. The introduction of these characters into O. sativa cultivars is difficult since crossing barriers cause spikelet sterility in F1. Backcrossing can restore fertility and recently
facilitated the development of fertile O. glaberrima × O. sativa ssp. japonica hybrid progenies for rain fed systems. With the objective to gain access to African rice germplasm for improvement of irrigated
rice, crosses were performed with eighteen O. glaberrima and twenty O. sativa ssp. indica accessions. In total about one hundred F1-hybrid grains were obtained. The F1 plants were all completely sterile and backcrossing
(BC) to O. sativa was performed in order to restore spikelet fertility. Monitoring of Tog5681 × IR64 hybrid progenies under field conditions
revealed a broad genetic diversity within the BC1 and BC2 populations. Some BC1 and BC2 progeny plants outperformed the O. sativa parent, indicating that the heterozygocity level and complementary gene action after two backcrosses are still sufficient
to positively influence plant vigor. Spikelet fertility of progenies was highly variable, but almost complete fertility was
already observed within the BC1F2 population. High spikelet fertility was preserved in one out of two analyzed BC1F3 families and inmost of the BC2F3 families. The ability to restore spikelet fertility within few generations and the potential of the genetic diversity present
in interspecific progenies facilitates the development of plant types specifically designed for the African irrigated and
lowland environment.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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A. Ngoran N. Zakra K. Ballo C. Kouamé F. Zapata G. Hofman O. Van Cleemput 《Biology and Fertility of Soils》2006,43(1):102-106
Litter decomposition of Acacia auriculiformis and Acacia mangium on sandy soil under coconut trees was studied in a field trial using the litterbag technique. The study was conducted during 2001 and 2002 in Ivory Coast. Litterbags containing 450 g of dried leaves and 450 g of dried small stems were set up in two coconut plantations of different ages, 3 and 20 years old. Dry matter weight and concentrations of total nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), and C/N ratio were determined at 90, 180, 270, and 360 days. The decomposition rate constant (k) and the half-life time decomposition of dry matter (T
1/2) were calculated. The study showed that A. auriculiformis and A. mangium have the same rate of decomposition on each coconut plantation. The k value varied from −1.592 day−1 to −1.492 day−1. The half-life time decomposition value of dry matter (T
1/2) ranged from 283 to 301 days. Nitrogen was released between 0 and 180 days with an N concentration for A. auriculiformis and A. mangium varying from 2.03 to 1.80% and 1.97 to 1.79%, respectively. After 180 days, the litters immobilized N. Phosphorus and Mg were released faster from A. mangium than from A. auriculiformis. A positive correlation was found between the N concentration of each Acacia species and the litter dry weight at 90 and 180 days. Likewise, C/N ratio was positively correlated with litter dry weight at 90 days. 相似文献
10.
Adje Olivier Ahimin Steven Johnson François N’Guessan Kouamé Kagoyire Kamanzi 《Journal of Sustainable Forestry》2019,38(1):46-53
Sustainable forest management is the process of managing forest to achieve one or more clearly specified objectives without diminishing the forest’s ability to continue providing goods and services in perpetuity. In this paper, we show how the African Timber Organization/International Tropical Timber Organization principles, criteria and indicators for the sustainable management of African forests can help timber companies assess their progress towards this goal in Gabon. Through a partnership between International Tropical Timber Organization project PD 124/01 Rev. 2(M), the World Wildlife Fund, and the ministry responsible for forests in Gabon, audits were conducted between 2012 and 2014 to evaluate the implementation of sustainable forest management in 14 forest concessions in Gabon. In general, results show that Principle 4, linked to the well-being of workers and local populations, proved the most difficult principle to implement, while Principle 3, dealing with maintaining ecological functions, was the least problematic. A number of companies were found to be experiencing significant difficulties in implementing management plans. It is also clear that independent forest certification has become a key element for ensuring the successful implementation of sustainable forest management. 相似文献