Effects of Bacillus subtilis metabolites on larval Aedes aegypti L     

Kannan Revathi  Rajamanickam Chandrasekaran  Annamalai Thanigaivel  Suyambulingam Arunachalam KirubakaranSubbiah Sathish-Narayanan  Sengottayan Senthil-Nathan 《Pesticide biochemistry and physiology》2013

The culture supernatant of a strain of Bacillus subtilis isolated from soil samples killed larvae of the mosquito Aedes aegypti. The metabolites produced by B. subtilis were characterized using high performance liquid chromatography (HPLC). Mortality rate was dose-dependent for all larval instars of A. aegypti. Log probit analysis (95% confidence level) revealed an LC₅₀ of 1.73 and an LC₉₀ 3.71 μg/ml. Molecular weights/masses of B. subtilis metabolites were confirmed using SDS–PAGE analysis. B. subtilis metabolites were confirmed using HPLC analysis. We demonstrate that secondary metabolites from B. subtilis have larvicidal activity against A. aegypti and may be suitable for the control of this and other mosquito vectors of human disease. The larvae to the metabolites, significant reduction in the activities of acetylcholinesterse, α-carboxylesterase, and acid phosphatases were recorded.  相似文献   

Morbidity,Mortality, and Risk of General Anesthesia in Horses     

Jonathan Mark Senior 《Veterinary Clinics of North America: Equine Practice》2013

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Effects of Farrowing Conditions on Behaviour in Multi-suckling Pens for Pigs     

L. Dybjær  A. N. W. Olsen  F. Møller  K. H. Jensen 《Acta Agriculturae Scandinavica, Section A - Animal Sciences》2013,63(2):134-141

This study investigated the effects of housing farrowing sows in either crates (C-sows) or a get-away system (G-sows) until day 11 after farrowing on the subsequent behaviour in multi-suckling pens. Emphases were placed on nursing behaviour patterns of relevance for the piglets' growth and survival in the multi-suckling pens. Ten groups of six sows were used. Behaviour was recorded for 24 h on days 1, 8 and 15 after the introduction to the multi-suckling pen. When the sows had farrowed in the get-away system significantly more nursings were initiated in the multi-suckling pen. Furthermore, the G-sows terminated a significantly smaller percentage of the nursings in the multi-suckling pens and there was significantly less cross-suckling compared with pens with C-sows. G-sows also tended (P = 0.08) to lose fewer piglets in the multi-suckling pens than C-sows. In conclusion, the results suggest that nursing behaviour in multi-suckling pens may be improved when the sows farrow in get-away systems as compared with crates.  相似文献   

Changes in the stand structure of a pine forest after rapid growth of Quercus serrata Thunb.     

M. Fujihara  Y. Hada  G. Toyohara 《Forest Ecology and Management》2002,170(1-3):55-65

We studied the species composition and stand structure of secondary pine forests affected by pine wilt disease, caused by epidemic attacks of the nematode Bursaphelenchus xylophilus, in western Japan. Based on the species composition, the vegetation was divided into four types: (1) Cladonia rangiferina, (2) Wikstroemia sikokiana, (3) Quercus glauca, and (4) Gleichenia japonica. The sequence of types from (1) to (3) represents a successional series in accordance with topographical position. The relative basal areas of Rhododendron reticulatum and Juniperus rigida in the C. rangiferina and W. sikokiana types were larger than in the Q. glauca type. The relative basal areas of Q. serrata, Clethra barbinervis, and Eurya japonica in the C. rangiferina and W. sikokiana types were less than in the Q. glauca type. The mortality of light-demanding trees was higher in the Q. glauca type than in the C. rangiferina and W. sikokiana types. In stands that were severely affected by pine wilt disease, light was reduced and soil became moist after rapid growth of Q. serrata and other species which are not affected by the disease. The numbers of species and components of evergreen broad-leaved natural forests were decreased, because pine forests in the study area had been cut frequently and the land had degraded. Pine wilt disease has shifted the dominance of pine forests from Pinus densiflora to deciduous oaks such as Q. serrata and physical conditions seemed to provide a safe site for shade-tolerant plant species, which are components of evergreen broad-leaved forests. Moreover, the seed dispersal of evergreen oaks appears to be an important factor in the succession to evergreen broad-leaved forest in degraded areas.  相似文献   

Effects of haying and agricultural practices on a declining species: The North American wood turtle, Glyptemys insculpta     

Raymond A. Saumure  Thomas B. Herman 《Biological conservation》2007,135(4):565-575

In North America, the spatio-temporal scale of deforestation has resulted in a 94% decrease in temperate forests within 360 years. Despite the enormous scale of this disturbance, agriculture is so pervasive in modern society that its impacts are highly underappreciated. We investigated the impact of current agricultural practices on a disturbance-dependent species in southern Québec, Canada. Of 30 wood turtles (Glyptemys insculpta) followed via radio-telemetry, 20% died as a result of agricultural activities. Anthropogenic mortality estimates for adults and juveniles in 1998 were 0.10 and 0.18, respectively. For 1999, these values were 0.13 and 0.17, respectively. Of those turtles that survived, many had injuries inflicted by agricultural machinery. Sub-lethal mutilation rates for adults were 90 ± 3% in both years, whereas the maximum frequency for juveniles was 57%. A Carapace Mutilation Index was derived to quantify the distribution and severity of injuries observed. Only male and juvenile Carapace Mutilation Index values differed significantly. Adults had significantly more carapace injuries and limb amputations on their right sides. This bilateral asymmetry of injuries resulted from of a combination of turtle flight behavior and traditional harvesting practices. We reiterate the recommendations of forage researchers: setting the cutting height of disc mowers to 100 mm increases harvest yields, reduces wear on machinery, and decreases soil erosion. A by-product of such a change in cutting height is that turtle mortality and injury rates should be reduced, as wood turtle carapace height is <87 mm. Without changes in agricultural practices, this population will be extirpated.  相似文献   

Baobab (Adansonia digitata L.) density,size-class distribution and population trends between four land-use types in northern Venda,South Africa     

Sarah M. Venter  E.T.F. Witkowski 《Forest Ecology and Management》2010

Baobabs are important to people's livelihoods as a source of food, fibre and medicine. Baobab products are increasingly being commercialised and exported around the world, and pressure on the resource is growing (Sidibe and Williams, 2002). This paper examines baobab population structure and trends in northern Venda, South Africa.  相似文献   

Effects of management, environmental and temporal factors on mortality and feed consumption in integrated swine fattening farms     

J. Oliveira  E. Yus  F.J. Guitin 《Livestock Science》2009,123(2-3):221-229

The purpose of this study was to assess the effects of management, environmental and temporal factors of farms and batches on mortality and feed consumed per market hog. Information of management, environmental and temporal factors from 158 all-in all-out finishing batches completed in 27 integrated fattening farms in Galicia (Spain) were collected from 1999 to 2002. Multilevel random effects models were used to determine the factors associated with the mortality and the average amount of feed provided per marketed hog. The level 1 unit was the finishing batch (batch level). At the level 2 the fattening farm where the batch of pigs was developed was introduced as random effects.A bad level of care provided by the farmer to the pigs increased the risk of mortality (P = 0.03). The mortality of the fattening batch was associated with the supplier sow farm (P < 0.01). The level of mortality of the batches of piglets entered the fattening farms both between January and April and October and December was higher than for batches incorporated from May to August (P < 0.01). The year when the piglets entered the farm was significantly associated with mortality (P < 0.01). The introduction of such variables in the multilevel model for mortality reduced the total unexplained variation by 41.06%. The proportion of the variation of the mortality attributable to the fattening farms was small (3.65%). The variability of mortality was higher when the placement of piglets was from September to December (P = 0.01).Higher consumption of feed was recorded when the feed was provided in a non-pellet form (P < 0.01). The introduction of piglets between September and December was associated with a higher consumption of feed (P < 0.01). The average final weight of the hogs was positively associated with the feed consumed per hog of the fattening batch (P < 0.01). The amount of feed provided per hog was statistically different among the years and these effects were modified by the level of mortality recorded in the batch and by the average weight of the marketed hogs. After introducing all the fixed effects in the multilevel model for feed provided per hog the unexplained variation at the farm and batch level was reduced by 47.72% and 85.35%, respectively. A considerable amount of variation of feed provided per hog resided at the fattening farm (32.50%). When the piglets were placed on September–December the variability of feed consumed was higher than in the other two periods of the year (P = 0.02). In conclusion, our study shows that specific factors of the batches are the main contributors to explain mortality. On the other hand, by improving permanent farm characteristics a substantial profit is expected in the long run as a result of lower feed costs.  相似文献   

Infectious agents associated with diarrhoea of calves in the canton of Tilarán, Costa Rica     

E. P  rez  A. Kummeling  M. M. H. Janssen  C. Jim  nez  R. Alvarado  M. Caballero  P. Donado  R. H. Dwinger 《Preventive veterinary medicine》1998,33(1-4):195-205

A case-control study of calves under 3 months of age was carried out by weekly visits to 15 farms in the canton of Tilarán, Costa Rica. Most farms were dedicated to beef or dual-purpose (DP) production. Faecal samples were collected over a 6-month period from a total of 194 calves with clinical signs and from 186 animals without clinical signs of diarrhoea as assessed by a scoring system. The samples were investigated for the presence of viruses, bacteria and parasites. Torovirus was detected for the first time in Costa Rica and was present in 14% of calves with diarrhoea and in 6% of the controls. Coronavirus and Rotavirus were less frequently encountered in either one of the groups (in 9 and 7% of scouring calves and in 1 and 2% of controls, respectively). Escherichia coli was detected in 94% of all the faecal samples, but isolates from only three samples from calves with diarrhoea contained the K99 antigen. Similarly, Salmonella was found only in scouring calves. Cryptosporidium oocysts were detected in animals with signs of diarrhoea, while other coccidia oocysts, Strongylida and Strongyloides eggs were frequently found in animals both with and without diarrhoea. A conditional logistic regression (CLR) analysis to compare healthy and scouring calves showed a significant difference with regard to the presence of Torovirus, Rotavirus and Coronavirus.  相似文献   

Simulation of tree and stand development under different environmental conditions with a physiologically based model     

R. Grote  M. Erhard 《Forest Ecology and Management》1999,120(1-3):59-76

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Population dynamics of the Bwindi mountain gorillas     

Martha M Robbins  Maryke Gray  Andrew M Robbins 《Biological conservation》2009,142(12):2886-2895

Mountain gorillas are critically endangered, with just a few hundred animals remaining in each of two populations: in Bwindi Impenetrable National Park in south-western Uganda and the nearby Virunga Volcanoes on the borders of Uganda, Rwanda and the Democratic Republic of Congo. While the life-history and population dynamics of the Virunga gorillas have been studied extensively, comparable information from Bwindi has not been reported. Such studies are difficult to conduct because gorillas are long-lived, have delayed reproduction, and monitoring known individuals requires habituation of social groups. Bwindi has experienced lower levels of human disturbance than the Virungas, yet its gorilla population has shown little or no growth over the past 20 years, while a subpopulation of study groups in the Virungas have grown by 3-4% per year. Here we show that the lower growth rate at Bwindi may arise mainly from lower fertility than the Virunga study groups, rather than higher mortality. This difference may indicate that the more frugivorous Bwindi gorillas have a slower life-history, or that they are closer to the carrying capacity of their habitat. The study groups at Bwindi had a higher growth rate than the broader population, possibly because they receive veterinary care and better protection from poachers, but further analysis is necessary to understand the complex interactions among human disturbance, ecology, and the gorillas’ population dynamics. Meanwhile, efforts to increase the Bwindi population should place emphasis on reducing human disturbances, improving our understanding of the impact of habitat quality, and ensuring that the gorillas can expand their home ranges into under-utilized areas of the park.  相似文献