| 词汇 | aphid |
| 释义 | aphid noun[ C ] uk /ˈeɪ.fɪd/ us /ˈeɪ.fɪd/ any of various small insects, such as the greenfly, that suck the juices of plants for food蚜虫 mikroman6/Moment Open/GettyImages Insect names anopheles ant beastie bedbug bee dragonfly dust mite earwig earworm elm bark beetle housefly insect jigger ladybird lepidopterist silverfish sow bug spider mite stick insect swallowtail Examples of aphidaphid The parents were transferred to new bean plants to avoid overcrowding and early death of plants and aphids. Unlike spotted alfalfa aphid, vein chlorosis was not observed after spotted clover aphid feeding in this experiment. Daily fecundity (number of nymphs produced per adult per day) varied with time for both aphid species and in each experiment (fig. 2). Twenty-four hours later, the plants were checked to see if the founding aphid had settled and any nymphs produced were counted. It was demonstrated that this spider did not simply consume greater quantities of aphids because it was bigger. Each year winged aphids migrate into the area in early summer, and populations expand on adult cereal plants. However, aphids from tobacco were not sampled from other host-plants in regions where tobacco is not common. What is responsible for the apparent specificity of aphid resistance genes? In this paper the hypothesis that the aphids' antennae are crucial for the wing induction in the presence of natural enemies is tested. Such dramatic responses to aphid feeding are unusual and probably indicate the involvement of toxic aphid saliva or hypersensitive reactions of the cypress trees. However, why the correlation was only significant at the higher aphid densities and not at the lower aphid densities remains unclear. The model assumes that, initially, both aphids and natural enemies coexist at low densities (mathematically, at a stable equilibrium). This aphid migrates to other parts, including below-ground stems, and so space is less likely to be a limiting factor. In general, the treatments with the largest concentrations of alfalfa also had the highest numbers of aphids. The observed population outbreaks and subsequent crashes correspond, essentially, to the aphid population switching rapidly from one locally stable manifold to another. These examples are from corpora and from sources on the web. Any opinions in the examples do not represent the opinion of the Cambridge Dictionary editors or of Cambridge University Press or its licensors. |
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