Topic
Aphid
About: Aphid is a research topic. Over the lifetime, 11380 publications have been published within this topic receiving 229721 citations. The topic is also known as: Aphidoidea & plant lice.
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TL;DR: The numbers and distribution of plants infected with aphid-borne viruses reflect the numbers and activity of the aphid vectors, and the extent to which aphid populations may be important vectors depends on the sources of virus which are available.
Abstract: Ecology attempts, among other things, to account for the numbers and spatial distribution of organisms. The ecology of viruses has usually been considered in terms of the number and spatial distribution of infected hosts (22, 114, 122). Although viruses cannot be regarded as small cells or micro organisms (85) , like other parasites, they must maintain their populations by a dependable means of transfer among susceptible hosts. The continued sur vival of a virus requires that the number of sources of virus shall never fall so low that transfer to other susceptible hosts becomes unlikely (22). The characteristics of a virus that permit or enhance natural transfer are thus undoubtedly subject to selective pressures. The relationships of a virus with its vectors must ensure the necessary frequency of transfers. Vectors must have a consistent relationship with host plants, although it may be only a matter of alighting by one or another noncolonizing species during migration. It is not surprising, therefore, that so many viruses are aphid-borne. Most species of angiosperms and gymno sperms, and some lower plants such as ferns, in the Northern Temperate Zone are hosts for at least one aphid species. The enormous reproductive potential and the behavioral patterns of aphids ensure their wide dispersal among populations of virus host plants. The numbers and distribution of plants infected with aphid-borne viruses reflect the numbers and activity of the aphid vectors. There is the added condition that the extent to which aphid populations may be important vectors depends on the sources of virus which are available. Under natural conditions and in many agricultural situations, these virus sources are plants infected by aphid transmission in previous years.
68 citations
TL;DR: It is suggested that S. chaetosiphon galls function to promote the breakdown of leaf protein, leading to an increased performance of gall‐inhabiting aphids.
Abstract: The nutrition hypothesis for the adaptive significance of insect gall formation postulates that galls accumulate higher concentrations of nutritive compounds than uninfested plant tissue, resulting in a high performance of the gall former. This hypothesis has been supported by some taxa of gall insects, but not by taxa such as cynipid wasps. Aphid galls are expected to require higher levels of nitrogen than other insects' galls with a single inhabitant, because aphid galls are required to sustain a number of aphids reproducing parthenogenetically over two generations. The present study tested this hypothesis by evaluating aphid performance and amino acid concentration in phloem sap, using the aphid Rhopalosiphum insertum (Walker) (Homoptera: Aphididae), which establishes colonies on leaves of Sorbus commixta Hedlund or in galls of the aphid Sorbaphis chaetosiphon Shaposhnikov (Homoptera: Aphididae). We prepared the gall and non-gall treatments on trees of S. commixta, in which R. insertum fundatrices were reared and allowed to reproduce. In S. chaetosiphon galls, R. insertum colonies propagated more rapidly, and the second generation grew larger and more fecund than on ungalled leaves. The amount of amino acids exuding from cut galled leaves was fivefold that in ungalled leaves; however, there was no significant difference in the amino acid composition between galled and ungalled leaves. In the intact leaves, total amino acid concentration in the phloem sap declined rapidly from late April to late May; however, the galls retained this high amino acid concentration in developing leaves for 1 month. These results indicate that the improved performance in R. insertum is ascribed to the increased concentration of amino acids in galled leaves. We suggest that S. chaetosiphon galls function to promote the breakdown of leaf protein, leading to an increased performance of gall-inhabiting aphids.
68 citations
TL;DR: Endophyte infection may protect meadow ryegrass from BYDV infections, which is transferred by aphids, which may be deterred by endophyte-origin alkaloids within the plant.
Abstract: We studied the effects of fungal endophyte infection of meadow ryegrass (Lolium pratense=Festuca pratensis) on the frequency of the barley yellow dwarf virus (BYDV). The virus is transferred by aphids, which may be deterred by endophyte-origin alkaloids within the plant. In our experiment, we released viruliferous aphid vectors on endophyte-infected and endophyte-free plants in a common garden. The number of aphids and the percentage of BYDV infections were lower in endophyte-infected plants compared to endophyte-free plants, indicating that endophyte infection may protect meadow ryegrass from BYDV infections.
68 citations
TL;DR: The potential for indirect competition between two phloem-feeding aphids as mediated by a shared host, pecan Carya illinoensis, is evaluated in a greenhouse experiment.
Abstract: 1. This study evaluates the potential for indirect competition between two phloem-feeding aphids as mediated by a shared host, pecan Carya illinoensis. In a greenhouse experiment, one of two aphid species, Monellia caryella and Melanocallis caryaefoliae,
68 citations
TL;DR: During summer 1998, significantly more parasitised wheat aphids were found in strip-designed plots than in the controls, and this higher parasitism rate was positively correlated to a higher parasitoid activity during May, due to the presence of alternative hosts.
68 citations