Dwarf shrub litter as a food source for macro-decomposers in alpine pastureland     

Julia Seeber  Reinhard Langel  Erwin Meyer  Michael Traugott 《Applied soil ecology》2009,41(2):178-184

Dwarf shrub litter is thought to be of poor quality and palatability for macro-decomposers. In laboratory feeding experiments, however, it was found that this litter type represents a potential food source for earthworms and millipedes. Here we tested whether this is true under natural conditions by conducting a 1 year field experiment on an abandoned alpine pasture in Tyrol (Austria). As the natural isotopic signatures of plant litter do not allow discriminating between different plant species, dwarf shrub litter, artificially enriched in ¹⁵N, was offered in experimental plots to the macro-decomposer community. Both the earthworm Lumbricus rubellus and the millipede Cylindrojulus fulviceps fed on dwarf shrub litter as indicated by their increased δ¹⁵N signatures, but IsoError analysis indicated a clear preference for grass litter for all macro-decomposer species investigated.Soil δ¹⁵N signatures were only marginally affected by the experimental provision of ¹⁵N-enriched dwarf shrub litter, whereas litter from other, unlabelled, plants became enriched by the isotopic tracer to some extent. Except for one grass species, plants harvested at the end of the experiment were not enriched in ¹⁵N, suggesting that the N-uptake from decomposing litter material by plants on abandoned alpine pastureland is slow.  相似文献   

Invasive black spiny‐tailed iguanas (Ctenosaura similis) on Gasparilla Island,Florida, USA     

Michael L. AVERY  Eric A. TILLMAN  Conny SPURFELD  Richard M. ENGEMAN  Kelin P. MACIEJEWSKI  Jessica D. BROWN  Emily A. FETZER 《Integrative zoology》2014,9(5):590-597

The native range of Ctenosaura similis extends from southern Mexico through Panama. From an initial introduction of 3 animals in 1979, the species now numbers in the thousands on Gasparilla Island in southwest Florida. In response to complaints of property damage from residents and threats to native species, local officials and the US Department of Agriculture Wildlife Services began a removal program in 2008. Through 2011, trappers removed 9467 ctenosaurs. The number removed declined from 32 iguanas/day in 2008 to 1.9 iguanas/day in 2011 despite no easing of the control effort. We necropsied 2757 ctenosaurs to document aspects of their natural history. Females outnumbered males overall, although the largest size class (>300 mm snout–vent length) included 32 males and just 2 females. Reproduction was seasonal. We found oviducal eggs in females from early Apr to early Jun, approximately 2 months later than C. similis in its native range. We trapped hatchlings from late Jul to early Oct coincident with the summer rainy season. Clutch size increased with female body size, with 62 being the largest clutch size recorded. In general, the biology of the invasive population on Gasparilla Island resembles native C. similis populations in Central America, except for the lack of large individuals. We suggest that shorter day length and colder temperatures create environmental conditions that are suboptimal for individual growth compared to those in the native range.  相似文献   

Light distribution in multispan gutter-connected greenhouses: Effects of gutters and roof openings     

Meir Teitel  Michael Deriugin  Vitaly Haslavsky  Josef Tanny 《Biosystems Engineering》2012,113(2):120-128

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美国大豆工业海洋网箱水产养殖技术近海海水鱼类养殖网箱工程技术手册(三十二)     

Michael C. Cremer  H.  R.  Schmittou Hsiang  Pin Lan  Jesse Chappell 《中国水产》2012,(4):81-82

(上接2012年第3期) (3)减阻设计方案3评估 第三种设计方案将减阻物放在相邻的两个侧面上.它的响应和设计方案1相同并且当网箱一开始运行时就沉入水中.当水速达到32厘米/秒时停止测试,因为此时可以观察到网箱沉至离水面7.3米一下(满标度),而且速度再增大时将撞击测试槽底部了(图28).  相似文献   

The pyrethrins and related compounds. Part XXXIV. Optimisation of insecticidal activity in non-esters     

Ahmet E. Baydar  Michael Elliott  Andrew W. Farnham  Norman F. Janes  Bhupinder P. S. Khambay 《Pest management science》1988,23(3):247-257

Optimisation of activity within the structural constraints defined by the preceding work, by varying the substituents on phenyl in the acid fragment (10 variations), the nature of the group fulfilling the dimethyl function (three variations), the central linking group (four variations) and the presence or absence of a 4-fluoro substituent in the alcohol fragment, has led to achiral compounds as active as bioresmethrin against houseflies and mustard beetles. Statistical analysis of the effects has shown that particular combinations, for instance the cyclopropyl form of dimethyl with a central E-alkene group (but not a central ether group), lead to higher activity than expected. 4-Fluoro substitution enhances activity more strongly against mustard beetles. Difluorocyclopropyl compounds are on average slightly more active than cyclopropyl analogues.  相似文献   

Synthesis and fungicidal activity of phenanthridinotriazines: A structure–activity relationship study     

Michael J. Coghlan  Wendell R. Arnold  Blake A. Caley 《Pest management science》1990,29(1):67-73

A series of analogous tetracyclic 1, 12b-dihydro-4H-1,2,4-triazino[4,3-f] phenanthridines and 4H,12bH-1,2,5-oxadiazino[5,6-f]phenanthridines was prepared and tested for control of Erysiphe graminis f. sp. tritici (the causal agent of powdery mildew in wheat). Several analogs showed exceptional activity at doses as low as 6.25 mg litre^?1 with substituted analogs VII, X , and XIV being the most potent. Singly substituted tetrahydrotriazinyl or oxadiazenyl rings with lipophilic aromatic components appeared to be the key requirements for optimal powdery mildew control. Substitution of the heterocyclic ring with multiple groups attenuated activity.  相似文献   

The pyrethrins and related compounds. Part XXVIII: Alkenyl- and alkynyl-substituted benzyl esters     

Michael Elliott  Richard L. Elliott  Norman F. Janes  Bhupinder P. S. Khambay  David A. Pulman 《Pest management science》1986,17(6):691-700

Over 100 benzyl esters of pyrethroidal acids were synthesised and tested for insecticidal activity to establish detailed structure–activity relationships in compounds with side-chains similar to those in the natural pyrethrins. Alkenyl, and corresponding alkynyl, side-chains were effective, both at the 3- and 4-positions, as were side-chains with extended substitution in either E or Z forms. A cyano group at the α-position increases activity if the side-chain is at C-3, but lowers it drastically if the substituent is at C-4. Similarly, methyl groups at C-2 and/or C-6 may increase activity whether the unsaturated side-chain is at C-3 or C-4, but only in the absence of an α-cyano group.  相似文献   

Influence of application methods on the degradation of permethrin in laboratory,soil aerobic metabolism studies     

Michael W. Skidmore  David Kirkpatrick  David Shaw 《Pest management science》1994,42(2):101-107

The effects of application rate, volume, solvent and soil moisture content on the kinetics of mineralization and degradation, of [¹⁴C] permethrin have been studied in a sandy loam soil under standard laboratory conditions. During the incubation period, up to 32 days, the temperature and moisture level of the soil were controlled. Apart from the effects of application rate, which have been widely reported, application volume had the most significant effect on mineralization rate and T_1/2. [¹⁴C]Permethrin, at a level of a 1 mg kg^?1 in the soil, applied in 100 μl of methanol, resulted in the evolution of 14% of the applied radiochemical as [¹⁴C] carbon dioxide over 30 days. The same level applied in 1000 μl mineralized at a faster rate, with 30% [¹⁴C]carbon dioxide evolved over 30 days. The test chemical applied to soil in methanol mineralized at a significantly faster rate than a similar concentration applied in ethanol. There was no significant difference when comparing applications made using acetonitrile with those using methanol or ethanol. The addition of formulation ingredients resulted in little or no variation in mineralisation rate compared to an equivalent application volume of methanol/water.  相似文献   

Oral administration of β-alanine modifies carnosine concentrations in the muscles and brains of chickens     

Shozo TOMONAGA  Yuji KAJI  Tetsuya TACHIBANA  D. Michael DENBOW  Mitsuhiro FURUSE 《Animal Science Journal》2005,76(3):249-254

Carnosine, and its derivative anserine, are known to function as anti‐oxidants and putative neurotransmitters. They are especially rich in the breast muscle (Musculus pectoralis superficialis, MPS) of chickens. To clarify whether the concentrations of carnosine and anserine are altered by dietary management, the effect of oral administration of their constituent, β‐alanine (β‐Ala), was determined in the MPS and brains of chickens. Birds were orally administered β‐Ala (22 mmol/kg) twice a day for five consecutive days (from 2 to 6 days old). In the MPS, carnosine was increased by β‐Ala, whereas anserine and taurine were decreased. The concentrations of other free amino acids in the MPS were also modified by β‐Ala. In the brain, the oral administration of β‐Ala increased anserine and carnosine and decreased taurine, but caused no changes to other free amino acid concentrations. These results suggest that orally administered β‐Ala increases carnosine concentrations in both the MPS and brains of chickens. However, the effects of β‐Ala on other concentrations differ depending on the tissues.  相似文献   

In vitro antimicrobial inhibition profiles of Mycoplasma bovis isolates recovered from various regions of the United States from 2002 to 2003.     

Ricardo F Rosenbusch  Joann M Kinyon  Michael Apley  Nathan D Funk  Sean Smith  Lorraine J Hoffman 《Journal of veterinary diagnostic investigation》2005,17(5):436-441

Antimicrobial therapy continues to be important in reducing losses due to pneumonic forms of Mycoplasma bovis disease in beef and dairy calves. Although M. bovis diseases have been documented as frequent and economically important in the United States, there are no published reports on the antimicrobial activity of approved compounds against US strains. In this study, the authors report on the activity of 9 different antimicrobials against 223 recently recovered isolates of M. bovis. These isolates represent accessions from 5 geographic regions of the United States and were grouped by 4 tissues of origin (milk, respiratory, joint, or ear and eye). A broth microdilution test was used to determine minimum inhibitory concentration (MIC) values by reading redox changes detected in broth with alamarBlue (resazurin) indicator. For each antimicrobial, the median, MIC50, MIC90, mode, and range were calculated, and the values used for comparisons. In the absence of accepted breakpoint values, published MIC cutoff values for animal mycoplasmas as well as Clinical Laboratory Standards Institute interpretive criteria were used as a reference to define in vitro activity. The MIC values from active antimicrobials were found to distribute independently of region of origin of the isolates or of tissue of origin. Enrofloxacin, florfenicol, and spectinomycin were found to be active compounds in vitro. Oxytetracycline and chlortetracycline were active against more than half of the isolates. Very few isolates were inhibited by tilmicosin and none by erythromycin, ampicillin, or ceftiofur. The antimicrobial profiles determined for these US strains were remarkably similar to those reported for European isolates. However, unlike in Europe, there appears to be no diversity of profiles when US isolates are grouped by region or tissue of origin.  相似文献