Quantitative comparison of Fusarium oxysporum competitiveness in relation to carbon utilization

Abstract The competitive saprophytic interaction between pathogenic and non-pathogenic strains of Fusarium oxysporum was investigated by studying their ability to competitively colonize sterilized soil. It was demonstrated that carbon was the first limiting substrate of Fusarium oxysporum growth in sterilized soil. Moreover, the efficiency with which glucose was utilized in the formation of propagules varied from one strain to another. Results of competitiion experiments showed that a linear relationship existed between the ratio of inoculum densities at the plateau (carrying capacity) and the ratio of inoculum densities incorporated into non-amended sterilized soil. The slope of the regression line indicated the competitiveness index, i.e. the competitiveness of a non-pathogenic strain in relation to that of a pathogenic strain. This parameter could be related to the yield coefficient of the strains in glucose-amended soil.     

The Why and How of Species

The biological species concept deals both with the meaning of the sexual species as a harmonious gene pool and with its protection against deleterious outbreeding (effected by isolating mechanisms). According to the Darwin-Muller-Mayr theory isolating mechanisms are acquired by incipient species during alloparty. Isolating mechanisms are not the result of ad hoc selection, but of a change of function of properties acquired during the preceding isolation of the incipient species. The role of behavioral properties (recognition) among the isolating mechanisms has long been recognized and described by naturalists but was rejected as basis of a species definition for a number of valid reasons.     

Effect of biologically active plants used as netst material and the derived benefit to starling nestlings

Summary The European starling Sturnus vulgaris preferentially incorporates fresh sprigs of particular plant species for use as nesting material. Chemicals found in these plants may act to reduce pathogen and ectoparasite populations normally found in nest environments. The present experiments were performed to test this Nest Protection Hypothesis. In the fild, we experimentally determined that wild carrot Daucus carota, a plant species preferred as nest material, effectively reduced the number of hematophagous mites found within nests relative to control nests without green vegetation. Chicks from nests containing wild carrot had higher levels of blood hemoglobin than chicks from control nests. However, there were no differences in weight or feather development. In the laboratory, we found that wild carrot and fleabane, Erigeron philadelphicus, (also preferred by starlings as nest material) substantially reduced the emergence of feeding instars of mites, while garlic mustard, Alliaria officinalis, (commonly available but not preferred) had little effect on the emergence of mites. We infer that preferred plant material may act to inhibit feeding or otherwise delay reproduction of mites, thereby reducing risk of anemia to developing nestlings.     

Biology ofTyta luctuosa [Lep.: Noctuidae] and its potential value as a biological control agent for the weedConvolvulus arvensis

The biology of the noctuid,Tyta luctuosa (Denis & Schiffermüller) (Lep.: Noctuidae), a defoliator of field bindweed,Convolvulus arvensis L., was studied in southern Europe.T. luctuosa is widely distributed and feeds on both thick stands and scattered host populations growing in a diversity of habitats. It undergoes 2 and perhaps a partial 3rd generation/year in southern Europe and is active during most of the growing season ofC. arvensis. In the laboratory the total time from egg to adult averages 45.6 days. There are 5 larval instars. Adult females deposit on average over 400 eggs. The larvae being able to feed and develop on native North AmericanCalystegia spp. in the laboratory, there are some reservations about its release in North America. However, the moth has potential value as a biological control agent for field bindeed in the western USA where it would fill an almost unoccupied niche.      

Lutte biologique et intégrée dans les vergers de citrus en zone méditerranéenne

Les problèmes posés par les ravageurs des Citrus ont pris une importance considérable au cours de ces 3 dernières décennies et cela pour plusieurs raisons:

Prediction of F3 row performance from F2 individual plant data in oats

Summary Parameters estimated from a Gardner-Eberhart analysis of the F₂ generation of a six-parent diallel in oats (Avena sativa L.) were used to compare methods for predicting the performance of F₃ row plots. The prediction methods were: (1) individual F₂ plant performance (F2I), (2) parent average plus F₂ plot deviations (PF2), (3) parent average plus weighted F₂ plot deviations (PF2P), (4) best linear unbiased prediction (BLUP) of parent average plus F₂ plot deviations (BPF2), and (5) BLUP plus weighted F₂ deviations (BF2). The F₂ single-plant traits used for prediction were biological yield to predict F₃ biological yield, whole plant and primary tiller grain yield for prediction of F₃ grain yield, and whole plant and primary tiller harvest index (HI) to predict F₃ HI. Prediction methods were evaluated by correlations between predicted and observed F₃ performance. Prediction methods and traits for which correlations were greater than for F2I included: BF2 for biological yield, PF2, PF2P and BF2 for whole plant grain yield, PF2, BPF2, and BF2 for primary tiller grain yield. None had a correlation significantly greater than F2I for either measure of HI, where heritability was large. PF2 is the recommended method for traits with low heritability because of its simplicity and because it had the largest or nearly the largest correlation for each of the yield traits. F2I is the recommended method for traits with larger heritability.Contribution No. 8821 of the U.S. Regional Pasture Research LaboratoryDeceased     

城镇污水诱发青蛙蝌蚪红细胞微核及其在环境监测中的应用

本文利用青蛙(Rana nigromaculata Hallowell)蝌蚪红细胞微核试验,作为检测城镇污水诱变活性的一种新的监测技术。在16d生活污水处理的实验中,青蛙蝌蚪红细胞微核细胞率2d后就呈现统计上的显著增加,并随处理时间的延长而增高,第12d达到最大值。在不同浓度混合污水处理实验中,蝌蚪红细胞微核细胞率呈现明显的剂量依赖性增加。上述实验证明城镇生活污水和混合污水都具有较强的诱变活性。作者从遗传毒理学的角度评价了湖北黄州综合生物塘系统对污水诱变活性的净化效能。城镇混合污水经综合生物塘各级塘处理,蝌蚪微核细胞率逐级下降,由进水的7.54‰下降到最后出水的1.52‰,接近对照(1.07‰)水平。其中综合生物塘的藻菌单元比水生植物单元对污水诱变活性具有更强的净化效力。本文提出污水“诱变指数”可作为综合生物塘一项功能评价指标。