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排序方式: 共有127条查询结果,搜索用时 15 毫秒
1.
Abstract. 1. Eurytoma gigantea Walsh is a specialist parasitoid of the tephritid gallmaker Eurosta solidaginis (Fitch).
2. In the natural environment the incidence of parasitism by Eurytoma is greater in small galls than in large ones.
3. Laboratory experiments demonstrated that small galls are not more frequently discovered; however, oviposition attempts on small galls were more likely to be successful.
4. Eurytoma spends much time probing galls too big to penetrate; this leads to a decrease in foraging efficiency when many large galls are present.
5. The chance of successfully penetrating a gall depends on the thickness of the gall wall and the length of the parasitoid's ovipositor.
6. A simulation model was constructed which shows that a gallmak-er's chance of being parasitized depends on gall size, the number of parasitoids that discover the gall, and their ovipositor lengths. 相似文献
2. In the natural environment the incidence of parasitism by Eurytoma is greater in small galls than in large ones.
3. Laboratory experiments demonstrated that small galls are not more frequently discovered; however, oviposition attempts on small galls were more likely to be successful.
4. Eurytoma spends much time probing galls too big to penetrate; this leads to a decrease in foraging efficiency when many large galls are present.
5. The chance of successfully penetrating a gall depends on the thickness of the gall wall and the length of the parasitoid's ovipositor.
6. A simulation model was constructed which shows that a gallmak-er's chance of being parasitized depends on gall size, the number of parasitoids that discover the gall, and their ovipositor lengths. 相似文献
2.
This study is the first report of an algal disease, developed in close association with an endophytic organism, documented for the southeastern Pacific. We describe a disease affecting wild populations of the red alga Iridaea laminarioides Bory in central Chile, characterized by gall development on the surface of sporophytic, cystocarpic, and immature thalli. These abnormal growths result in severe morphological alterations of the affected thalli. Diseased fronds display an aggregated spatial distribution and occur throughout the year, with a maximum in summer followed by a decline in winter. The presence of galls was not associated with broken or torn fronds. Although causality has not been unequivocally demonstrated, our field and laboratory observations indicate a strong association of the galls with infections by an endophytic cyanobacterium, probably belonging to the genus Pleurocapsa. 相似文献
3.
A non-gall-forming aphid, Macrosiphum euphorbiae, was reared within the galls of Dysaphis devecta and Aphis pomi which had been induced in apple seedlings. Similar aphids were also reared on ungalled seedling leaves of a similar age and also on mature leaves and in old galls.There is a weak positive linear relationship between lipid content and pre-reproductive adult dry weight, but aphids living on young galled or ungalled plant tissue have 30% lipid compared to 11% for aphids living on old plant tissue. Adult aphids gradually decline in weight, losing between 24% and 38% of their pre-reproductive biomass before death. The energy content of this loss subsidieses reproduction. Reproduction of aphids feeding in old galls or on mature leaves was negligible, but on younger tissues average fecundity was 31, there being little difference between aphids living on galled and ungalled tissue. There is no simple relationship between pre-reproductive adult embryo content and fecundity.The principal factor mediating honeydew production was aphid size and this factor overrides any variation caused by different feeding sites. Honeydew production averaged 0.43 mg during a life of 30 days. Aphids successfully completing their life cycle have a life-time energy consumption of 30.58 joules of which 18% is lost as heat during respiration (R), 30% is contained in honeydew (F+U), 1% is contained in exuviae (Pe). Larval growth accounts for 17% (Pg), and adult reproduction for 34% (Pr).The P/C ratio for M. euphorbiae is 53% and is broadly comparable with aphids living on herbaceous plants.
Résumé Un puceron ne formant pas de galles, Macrosiphum euphorbiae, a été élevé dans des galles de Dysaphis devecta et Aphis pomi formées sur semis de pommiers. D'autres M. euphorbiae ont été élevés sur feuilles sans galles du même âge provenent de semis identiques, sur feuilles mûres et sur vieilles galles.Il y a une faible relation positive linéaire entre la teneur en lipides et le poids sec des adultes avant la reproduction, mais les pucerons élevés sur tissus végétaux jeunes avec ou sans galles contiennent 30% de lipides contre 11% pour ceux élevés sur tissus âgés. Le poids des pucerons adultes diminue progressivement, la perte avant la mort se situant entre 24 et 38% de la biomasse avant la reproduction. Le contenu énergétique de ces pertes alimente la reproduction. La reproduction de pucerons consommant les vieilles galles ou les feuilles mûres était négligeable, mais sur jeunes tissus la fécondité moyenne était de 31-avec peu de différences entre pucerons sur galles ou feuilles-. Il n'y a pas de corrélation simple entre le contenu en embryon des adultes avant la reproduction et la fécondité.Le principal paramètre conditionnant la production de miellat est la taille du puceron; ce paramètre surpasse toute variation provoquée par les divers lieux d'alimentation. La production moyenne de miellat est de 0,43-mg pendant une vie de 30 jours. Les pucerons accomplissant leur cycle avec succès utilisent pendant leur vie 30,58 joules, dont 18% sont dissipés sous forme de chaleur pendant la respiration (R); le contenu du miellat (F+U) correspond à 30%, et 1% est contenu dans l'exuvie (Pe). La croissance larvaire (Pg) utilise 17%, et l'activité reproductrice des adultes (Pr) 34% de l'énergie. Le rapport P/C-53% pour M. euphorbiae-est globalement comparable à celui des pucerons vivant sur plantes herbacées.相似文献
4.
The adaptive significance of insect gall distribution: survivorship of species in xeric and mesic habitats 总被引:4,自引:0,他引:4
Summary We studied the relationship between habitat moisture and gall-forming insect populations. Population sizes for most galling taxa were significantly larger in xeric habitats compared with mesic habitats. Our results indicate that the differential abundance of galling insects in these habitats is due primarily to differential mortality and survivorship. Mortality factors acting upon eight insect galling species (belonging to eight genera and four families) were measured on six species (five genera and five families) of host plants. Survival was significantly higher for galling populations inhabiting xeric habitats compared with mesic habitats. Parasitism was higher in mesic habitats in seven of eight habitats and fungus-induced diseases were higher in five of seven habitats. Mortality due to predation and other (unknown) factors showed no clear trends. Overall, there was a tendency towards lower mortality and consequently higher survival for populations inhabiting xeric habitats. We hypothesize that reduced mortality caused by natural enemies and endophytic fungi has contributed to the speciation and radiation of galling insects in apparently harsh environments. 相似文献
5.
6.
7.
《Fungal Ecology》2019
The mushroom-forming genus Squamanita comprises 10 described species, all parasitic on basidiomes of other members of the order Agaricales, including members of the genera Cystoderma, Galerina, Inocybe and Hebeloma. Here we report an anatomical investigation of the stipitate “mycocecidium’ (=fungus gall) formed on the basidiome of Cystoderma amianthinum (“powdercap”) by S. paradoxa (“powdercap strangler”), alongside the development of taxon-specific-PCR primer to localise the presence of S. paradoxa/C. amianthinum mycelia within mycocecidia, in associated plant tissues and apparently healthy host basidiomes. Dissection of fungarium samples also confirmed these findings, whilst ITS barcode sequencing of all available samples held at the RBG Kew and Edinburgh fungaria did not reveal any variation in ITS sequences within UK populations of S. paradoxa or the closely related S. pearsonii. The absence of any 13C or 15N isotopic differences between C. amianthinum and S. paradoxa suggests that S. paradoxa is nutritionally dependent on its host. The status of C. amianthinum as host of S. pearsonii is also confirmed. 相似文献
8.
Evolution of the gall wasp-host plant association 总被引:1,自引:0,他引:1
Gall wasps, or cynipids, form the second largest radiation of galling insects with more than 1300 described species. According to current views, the first cynipids were phytophagous and developed in herb stems of the Asteraceae without modifying plant growth or development. The first galls were supposedly multichambered stem swellings, and subsequent trends involved increase in gall complexity and reduction in the number of larval chambers. Gall wasps also have many of the features believed to be characteristic for phytophagous insects radiating in parallel with their host plants. We tested these hypotheses by mapping characters onto a recent estimate of higher cynipid relationships from a morphology-based analysis of exemplar taxa, controlling for phylogenetic uncertainty using bootstrapping. Characters were also mapped onto a metatree including all gall wasps, assembled from phylogenetic analyses as well as recent classifications. The results contradict many of the current hypotheses. The first cynipids with extant descendants were not Asteraceae stem feeders but induced distinct single-chambered galls in reproductive organs of herbaceous Papaveraceae, or possibly Lamiaceae. There has been a general trend toward more complex galls but the herb-stem feeders evolved from ancestors inducing distinct galls and their larval chambers are best understood as cryptic galls. Woody hosts have been colonized only three times, making the apparently irreversible transition from herbs to woody hosts one of the most conservative features of the gall wasp-host plant association. The evolution of host plant preferences is characterized by colonization of preexisting host-plant lineages rather than by parallel cladogenesis. Cynipids are mono- or oligophagous and host-plant choice is strongly phylogenetically conserved. Yet, the few major host shifts have involved remarkably distantly related plants. Many shifts have been onto plant species already exploited by other gall wasps, suggesting that interspecific parasitism among cynipids facilitates colonization of novel host plants. 相似文献
9.
G.R. Julião M.E.C. Amaral G.W. Fernandes E.G. Oliveira 《Biodiversity and Conservation》2004,13(11):2055-2066
The aim of this study was to (i) measure differences in species richness between edge habitats versus interior habitats, or more precisely the edge effect, and (ii) test the species–area relationship for gall-forming insects in natural forest patches in a Brazilian floodplain (Pantanal of Mato Grosso do Sul). These patches are regionally known as capões, basically composed of woody vegetation. Twenty-seven patches were surveyed. In each patch two transects were conducted for gall sampling. One transect encircled the patches while the other was conducted in the interior of the patch, totaling 54h of sampling. Host plant and galling insect species composition differed quite characteristically between the edge and the interior of patches, but galling insect richness did not. When insect gall richness was expressed as the ratio between insect gall and host plant richness (gall per plant ratio), a weak species–area relationship was found. Our results suggest that the number of galling insects per individual plant is not affected by the size of the patch. Despite these results, the natural forest patches found in this region seem well suited for long-term studies addressing species–area relationships. With regard to herbivorous insects, these studies should be combined with research on host plant dynamics during flooding and dry seasons. 相似文献
10.
Gall formation in Prionitis lanceolata is associated with aspecific eubacterium (Proteobacteria [alphasubclass], Rhodobacter grouping), which, typical ofbacterial symbionts, has not yet been cultivated or isolated in pureculture. This investigation tested the hypothesis that P.lanceolata gall formation was caused by the associated eubacteriumusing a species-specific rDNA probe (S-S-P.l.sym-0949-a-A-25) toidentify and assay for symbiont presence during consecutive laboratoryinduction trials. Gall induction was quantified and whole-cell in situhybridization used to determine the relative percentage of symbioticeubacteria in inoculation homogenates. In situ hybridization ofsymbionts in sections allowed localization and monitoring of thismicrobe during gall development. Induction trial results indicate asignificant correlation between bacterial symbiont presence and gallinitiation (P = 0.00005). The gall bacterium comprisedthe majority of the eubacteria hybridized in laboratory inductionhomogenates (85-97%), in galls induced in the laboratoryand in three algal populations in nature. The evidence presented heredemonstrates the causative role of the identified eubacterium in gallinduction and formation. This investigation is significant in theapplication of molecular methods towards understanding the roles ofnoncultivable marine bacteria in marine algal-microbeinteractions. 相似文献