Controlling pests of tropical legumes; current recommendations and future strategies     

Brian M. Gerard 《Pest management science》1978,9(5):465-477

Legumes have evolved effective defences against many pests by accumulating high levels of poisonous or indigestible compounds, pubescence and vigorous growth. These defences are greatly reduced in many cultivars of cowpea and common bean, which are susceptible to a succession of pest complexes. Stem pests and defoliators may kill seedlings but well-established plants tolerate heavy insect damage to leaves, flowers and green pods before pod or grain yields are reduced; virus vectors and root-knot nematode may be of greater importance. Generally, pod-borers, pod-sucking bugs and seed beetles are the main key pests. Control programmes are based on post-flowering treatments with broad spectrum insecticides. Battery-powered, controlled-droplet application machines are ousting knapsack sprayers in small-scale farming and competing with tractors and aircraft in larger units; subsistence cropping is still predominant and most legume crops remain unsprayed. Consequently, current emphasis is placed on developing cultivars with high yield potential and multiple pest and disease resistance. Insect infestations are lower in most other major legume crops largely due to pubescence (e.g. soybean, blackgram, greengram), fruiting in the dry season (e.g. pigeonpea, chickpea) or geocarpy (e.g. groundnut). Future entomological research will presumably concentrate on assessing the status of pests on resistant cultivars and introducing integrated control methods for the key pests.  相似文献   

Book reviews     

Dennis Michael Warren  Gerard McKiernan  Vassiliki Betty Smocovitis  Lori Ann Thrupp 《Agriculture and Human Values》1991,8(1-2):179-184

  相似文献   

Experimental data for structure papers     

Jones TA  Kleywegt GJ 《Science (New York, N.Y.)》2007,317(5835):194-195

  相似文献   

Metabolic regulation of brain Abeta by neprilysin     

Iwata N  Tsubuki S  Takaki Y  Shirotani K  Lu B  Gerard NP  Gerard C  Hama E  Lee HJ  Saido TC 《Science (New York, N.Y.)》2001,292(5521):1550-1552

Amyloid beta peptide (Abeta), the pathogenic agent of Alzheimer's disease (AD), is a physiological metabolite in the brain. We examined the role of neprilysin, a candidate Abeta-degrading peptidase, in the metabolism using neprilysin gene-disrupted mice. Neprilysin deficiency resulted in defects both in the degradation of exogenously administered Abeta and in the metabolic suppression of the endogenous Abeta levels in a gene dose-dependent manner. The regional levels of Abeta in the neprilysin-deficient mouse brain were in the distinct order of hippocampus, cortex, thalamus/striatum, and cerebellum, where hippocampus has the highest level and cerebellum the lowest, correlating with the vulnerability to Abeta deposition in brains of humans with AD. Our observations suggest that even partial down-regulation of neprilysin activity, which could be caused by aging, can contribute to AD development by promoting Abeta accumulation.  相似文献   

Cyclic variation and solar forcing of Holocene climate in the Alaskan subarctic   总被引：2，自引：0，他引：2  

Hu FS  Kaufman D  Yoneji S  Nelson D  Shemesh A  Huang Y  Tian J  Bond G  Clegg B  Brown T 《Science (New York, N.Y.)》2003,301(5641):1890-1893

High-resolution analyses of lake sediment from southwestern Alaska reveal cyclic variations in climate and ecosystems during the Holocene. These variations occurred with periodicities similar to those of solar activity and appear to be coherent with time series of the cosmogenic nuclides 14C and 10Be as well as North Atlantic drift ice. Our results imply that small variations in solar irradiance induced pronounced cyclic changes in northern high-latitude environments. They also provide evidence that centennial-scale shifts in the Holocene climate were similar between the subpolar regions of the North Atlantic and North Pacific, possibly because of Sun-ocean-climate linkages.  相似文献   

An alternative flavin-dependent mechanism for thymidylate synthesis     

Myllykallio H  Lipowski G  Leduc D  Filee J  Forterre P  Liebl U 《Science (New York, N.Y.)》2002,297(5578):105-107

Although deoxythymidylate cannot be provided directly by ribonucleotide reductase, the gene encoding thymidylate synthase ThyA is absent from the genomes of a large number of nonsymbiotic microbes. We show that ThyX (Thy1) proteins of previously unknown function form a large and distinct class of thymidylate synthases. ThyX has a wide but sporadic phylogenetic distribution, almost exclusively limited to microbial genomes lacking thyA. ThyX and ThyA use different reductive mechanisms, because ThyX activity is dependent on reduced flavin nucleotides. Our findings reveal complexity in the evolution of thymidine in present-day DNA. Because ThyX proteins are found in many pathogenic microbes, they present a previously uncharacterized target for antimicrobial compounds.  相似文献   

SYNCHRONY IN FLOCK WHEELING     

Gerard RW 《Science (New York, N.Y.)》1943,97(2511):160-161

  相似文献   

Deep-Sea Drilling by JOIDES     

Gerard R 《Science (New York, N.Y.)》1969,163(3864):232-233

  相似文献   

Potential freshwater reservoir in the New York area     

R D Gerard 《Science (New York, N.Y.)》1966,153(738):870-871

Estimates of the water budget of Long Island Sound suggest that it could become the largest reservoir in the United States, with a freshwater surplus equal to 12 times the present needs of New York City. The engineering aspects of this undertaking are within the scope of present technology. The dam structures required to isolate this area from the sea could serve as important highway links in place of highway-bridge projects presently under study.  相似文献   

Potential of SPME-GC and chemometrics to detect adulteration of soft fruit purées     

Reid LM  O'Donnell CP  Downey G 《Journal of agricultural and food chemistry》2004,52(3):421-427

The potential of combining solid-phase microextraction (SPME) with gas chromatography and chemometric data analysis to differentiate between pure strawberry samples (Fragraria ananassa) and strawberry samples adulterated with 10, 40, and 70% (v/v) apple purée was investigated. The method involved the extraction of aroma volatiles from the headspace of the purée samples using a SPME fiber followed by GC analysis with flame ionization detection. The principal component analysis (PCA) data matrix consisted of the relative percent peak areas of 37 compounds deemed to be significant in the differentiation of the samples on the basis of adulteration. The PCA results clearly showed that differentiation of the adulterated and unadulterated samples was possible, particularly at the higher levels of adulteration. Partial least-squares regression (PLSR) using a dummy set of Y variables (set to 0 for unadulterated and 1 for adulterated samples) resulted in clear discrimination between unadulterated purées and those containing 40 and 70% (v/v) apple. PLSR using a second set of Y variables, consisting of the actual level of adulteration, enabled quantification of apple purée with a standard error of prediction of 11.6%, implying a minimum detectable level of 25% (v/v) apple. GC-MS analysis enabled identification of the compounds with the greatest influence on sample differentiation. These compounds were identified as hexanoic acid, 2-hexenal, and alpha-farnesene, all of which are key aroma compounds in apples.  相似文献