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EN
Post-industrial sites form a unique phenomenon in the landscape. They enable us to study the human-altered succession of communities. Regarding this, we studied an ant community in three types of habitats – reclamation and spontaneous succession in an ore basin together with unaltered surroundings in the Czech Republic. More than 30 years after being abandoned, the site with spontaneous succession was more species rich than the reclaimed one. Moreover, spontaneous succession created a habitat that was more similar regarding ant diversity to the unaltered surrounding environment than that after traditional reclamation. Ants dependent on tree vegetation were rather rare in both the reclaimed and spontaneous succession parts of the ore basin compared to the surrounding landscape. The relative abundance of socially parasitic ants increases in a gradient from the reclaimed basin, through the basin with spontaneous succession to the unaltered surroundings. Our study highlighted the fact that the formation of ant communities at post-industrial sites is clearly more complicated than for other arthropods, including related aculeate hymenopterans. The potential of both reclaimed and spontaneous succession basins for harbouring endangered species appeared to be lower for ants than for other taxa indicated by recent studies.
2
Content available remote Lasius niger (L.) Ants Invade the Web of an Agelenid Spider
EN
Black garden ants Lasius niger (L.) were observed to invade a web of an agelenid funnel spider (Agelena labyrinthica Clerck or Allagelena gracilens C. L. Koch) and to take the entangled prey away, probably after driving the resident spider out of the web. The observation adds to a few examples of ants invading spider webs and suggests complex interactions between ants and funnel spiders which are known to feed on rather than being ousted by ants.
PL
Przedstawiono wstępne wyniki badań prowadzonych w latach 2008-2009 na obszarach oddziaływania przemysłu wapiennego na Kujawach w Północnej Polsce. W trakcie prowadzonych pracodłowiono 93 gatunki żąłówek - Crabronidae (40 gatunków), Chrysididae (18 gatunków), Vespidae (15 gatunków), Pompilidae (10 gatunków), Sphecidae (6 gatunków), Mutillidae (2 gatunki), Scoliidae (1 gatunek) oraz Tiphiidae (1 gatunek).Uzyskane wyniki wskazują, że przemysł nie zawsze musi kojarzyć się z negatywnym oddziaływaniem na faunę czy florę.
EN
Preliminary field research was conducted in 2008-2009 in areas directly affected by lime industry in the region of Kujawy (Kuyavia) in northern Poland. In the course of the work of 93 species caught Aculeata - Crabronidae (40 species), Chrysididae (18 species), Vespidae (15 species), Pompilidae (10 species), Sphecidae (6 species), Mutillidae (2 species), Scoliidae (one species) and Tiphiidae (one species). Results of this study imply that industry does not always have a negative effect on the local fauna or flora.
EN
This paper tests the recent published synthetic theory of biodiversity of Ritchie and Olff (1999) using data on parasitic Hymenoptera and soil living Diptera. Neither the predicted size dependent size ratio patterns, nor the left skewed species number-size class ratios, nor right skewed species richness-productivity patterns were found. It is concluded that the basic assumptions of the theory (self similarity of habitat, food, and resource distribution over ecological relevant scales) is not applicable at fine scales and to guilds of higher trophic levels. Whether in general the assumptions are applicable to plants and phytophages has to be decided by further studies.
5
Content available remote Ecological characteristic of rare species : the case of parasitic hymenoptera
EN
Ecological characteristic of relatively rare (singleton) hymenopteran species sampled in a beech forest on limestone are studied. No marked differences between singleton and non-singleton species occurred in regard to guild membership, stratum of host attack and phenology. There was however a strong effect of sample size on the fraction of singletons. Body size and phylogenetic position also appeared to influence rarity, but it proofed to be difficult to separate the effects of both variables. Rare species appeared to have larger density fluctuations but - in line with the theory of local mate competition - lover sex rations than more common species. Brachypterous and apterous species had lower fractions of singletons. This result contradicts theoretical expectations of metapopulation models.
EN
In a beech forest on limestone (Northern Germany) community structure and coexistence of a community of phorid (Diptera) parasitoids (Aspilota and Orthostigma spp., Hymenoptera, Braconidae) was studied. A classical niche analysis including character displacement, temporal and spatial segregation and density fluctuations could not clearly separate the species. In a case where such a separation by morphological factors was possible, hosts and spatial distribution of this species were the same as in morphologically different species. As prediced from aggregation theory of coexistence all species were highly aggregated but aggregation and density appeared not to be correlated. In line with the core-satellite hypothesis bimodal species rank order distributions (temporal and in relation to density) with a high number of rare species were found and patch density was correlated with number of patches occupied. Relative abundance distributions were fitted by Zipf-Mandelbrot but not by log-normal or log-series models.
EN
In 1986 and 1988 the hymenopterous fauna of a semixerophytic meadow on limestone near Gottingen (FRG) was studied using ground-photo-eclectors. A total of 4982 speciments belonging to 475 different species were collected. Extrapolations from double-log functions revealed that there may be as many as 1330 parasitoid species present per year. 455 of the 475 species were parasitoids. 155 of them attack dipterans. 48 lepidopterans, 36 beetles, 23 wasps, 22 plant hoppers and 13 aphids, 47 of the species are egg-parasitoids and parasitoids of miners, ectophytophages count for 44 of the wasp species. The abundance of the wasp fauna was rather high (1120+-53 ind. m^-2 a^-1 (1986) and335 +-42 ind. m^-2 a^-1 (1988). Most abundant were the parasitoids of miners, gall-makers and the eggparasitoids. Compared with the high abundance the biomass was low. In 1986 the wasps weighed a total of 194 +-24 mgDW m^-2 a^-1 and in 1988 only 69+-20 mgDW m^-2 a^-1. The parasitoids of ectophytophagous lepidopter ans and coleopterans counted for more than half of the whole biomass.
EN
This paper tests the hypothesis that the density - weight distribution of species assemblages may be generated alone by underlying weight dependent density fluctuations by constructing several model species - weight and density - weight distributions. The simulations revealed that indeed even a slight dependence of density fluctuation on body weight generated typical density - weight distributions with upper density boundaries and triangular shapes. Other ecological explanations, such as metabolic constrants or arguments based on fractal geometry, may therefore not be necessary to explain the pattern. In a second step of analysis the density - weight relationship was combined with various species - weight distributions (computed over log[2] weight classe) to show that in nearly all parameter settings steadily rising biomass distributions with a decline only towards the largest weight classes result. The generality of the equal biomass hypothesis is therefore rejected. A general model is developed to explain several of the patterns in density - weight and species - weight plots assuming only underlying weight dependent speciation and extinction rates and weight dependent density fluctuations.
EN
The stability of the community structure of the parasitic Hymenoptera of a beech forest on limestone (northern FRG) was studied. The annual number of species was around 350 to 450 with a high degree of species turnover. In a comparison of the study years the species identity of the abundant species turned out to be low and their dominance rank order was highly variable. The yearly sequence of emergence appeared to be constant. Density fluctuations of the species were high and positively correlated with mean density and negatively with the weight of the species. No clear common temporal trends in density could be detected. Host guild, stratum of host attack or number of generations did not detectably influence the degree of density fluctuations of the species. The findings are discussed in the context of concepts of stability and classifications of communities and it is concluded that this hymenopteran community is best described as non-interactive and non-stable.
EN
In a beech forest on limestone, the community of carrion (dead Arion ater slugs) exploiting Diptera and their parasitoids (Hymenoptera) was studied. The carcass sustained 17 species of Diptera and 12 of Hymenoptera. With the exception of Kleidotoma psiloides (Eucoilidae), all of the parasitoid species bred were polyphagous and attacked all of the fly species present. The populations of the fly and wasp species were highly aggregated. The degree of aggregation depended in an inversely manner on the density. The dispersion of the parasitoids was independent from the number of hosts. Diptera, which lay their eggs in a late stage of decay, showed a negative correlation between aggregation and the weight of the slugs. There was no interspecific competition detectable between the fly species. The parasitoids did compete markedly only at high levels of parasitism. The parasitoids showed only a weak (negative) density dependent reaction to the numeber of hosts present. The degree of density dependence was more pronounced in the more infrequent species. The total parasitoid numbers increased in a linear manner with increasing host densities, and therefore the overall parasitism rate was roughly constant for different host numbers. Large predators and necrophages (Silphidae, Carabide, Arion ater) had a high impact on the mortality of the flies and wasps. in experimental boxes that allowed free access to these species, they totally prevented the development of phorid flies and their parasitoids.
EN
In the parasitic Hymenoptera of a dry meadow on limestone and a beech forest on limestone (both near Gottingen, FRG) three porphological parameters were analyzed and related to environmental factors: the relative wine surface, the ovipositor length and the relative length of the hind leg (as a measure of body-compactness). Two coefficients of wing surface and one of body-compactness are developed. Wing surface and length of legs turned out to be allometrically related to the thorax volume of the species. Soil living parasitoids had the relatively largest wings and longest hind legs; parasitoids of the canopy level showed the opposite trend. On the dry meadow many more wingless or short winged species occurred than in the beech wood; these species also reached higher densities. In the fully winged species there were more species with smaller wing surfaces on the dry meadow than in the beech wood. Idiobiontic parasitoids appeared to have much higher proportions of wing reduced species to han koinobiontic species. The impact of these differences in morphology on community structure is discussed.
EN
The density - weight distributions of the hymenopteran species in a beech forest on limestone and a dry meadow on limestone near Gottingen (FRG) were studied. Species and density distributions (logarithmic size classes) turned out to follow normal and log-normal distributions with the meadow having the more narrow shape. Upper weight classes accumulated more total biomass m^-2 than lower ones, resulting in a rejection of the equal biomass hypothesis in the case of the Hymenoptera. An analysis of the density - weight relationship revealed an upper density boundary for the hymenopteran species which can be defined by second order polynomial functions. Mean and upper densities of small hymenopteran species ranged well below their boundaries, with an asymptotic relationship between distance from the boundary and species weight. The area defined by the boundaries may mark the area of stability: exceeding the species specific boundary was always followed by a marked decline oreven a collapse of population density.
EN
In a mixed beech forest growing on limestone, the effect of an enhanced and a reduced layer of leaf litter on the emergence of parasitic Hymenoptera (as well as their hosts) was studied. A long term increase (4 years with an initially 5-fold value) of the leaf layer and a short term experiment (1 year, factor 5) resulted in arise of the total density of soil living parasitoids. The abundance of parasitoids which attack hosts in the herb layer or canopy declined. However, in both groups diversity and evenness was lowered. A reduction of the layer of leaf litter resulted in lower densities of the parasitoids of soil living hosts, but higher abundances of the parasitoids of hosts in other strata. The lacking leaf layer caused a reduction in the number of species and lowered both diversity and evenness. The lacking leaf layer also caused changes in the species composition. Experiments with dead snails to attract necrophagous insects and their parasitoids covered by different amounts of leaf litter revealed a species specific reaction to the leaf cover. Total parasitism rates were not reduced under a thick layer of leaf litter. No protective function of the leaf cover could be detected.
EN
The sex ratio of the parastic Hymenoptera of a beech forest on limestone near Gottingen (FRG) was studied using ground-photo-eclectors. Judged from the mean sex ratios the parasitoids could be separated into 4 groups. Parasitoids of miners and gall-makers had the highest sex ratios (30 to 40% males) and less than 5% of the species were thelytokous. The species which attack soil-living sapro- or mycetophagous Diptera as well as the parasitoids of ectophytophages had (on average) 20 to 30% males and only 1.5% of them were thelytokous. Parasitoids of sap-suckers and egg-parasitoids usually had sex ratios below 20% males and 29% of them were thelytokous. The lowes sex ratios (below 10% males) and the highest number of thelytokous species (30%) were found among hyperparasitoids and parasitoids of soil-living Staphylinidae. No clear trend was detectable between the sex ratio and the density of the species. The density fluctuations and the degree of aggregation of the species influenced the sex ratio. The data are consistent with the hypothesis that K-selected parasitoid species have higher sex ratios on average. Koinobiontic species (mostly parasitoids of gall-makers and miners) had (on average) significantly higher sex ratios if their host lives in the herb or crown layer (32% versus 21%). They also produced more males if they are univoltine (32% versus 22%) and hibernate as larvae or pupae (30% versus 17%). After a MANOVA-analysis the voltinism turned out to be the main infuencing factor. There was a trend towards higher percentages of males in the summer generation.
EN
Between 1980 and 1987 a beech forest (Fagus sylvatica) on limestone near Gottingen (FRG) was studied using ground-photo-electors. 720 species of Hymenoptera were detected. 669 of the species were parasitoids, 29 phytophagous Tenthredinidae, Cynipidae and Eurytomidae, 9 ants, 4 vespids and 9 nest-building sphecids, megachilids, andrenids and bumble bees. Even after 8 years of sampling a great number of species seems to remain undetected. Estimates of extiction and immigration rates indicate species turnover rates of at least 5 to 10%. The abundance of the parasitic Hymenoptera ranged between 123 +- (1981) and 1078 +- 186 (1984) ind. m^-2 a^-1. The most important groups were the parasitoids of Diptera with 56 +- 15 (1981) to 936 +- 164 (1984) ind. m^-2 a^-1. As judged by the sorting according to parasitoid guild, the parasitoids of gall-makers (23 +- 9 to 880 +- 163 ind. m^-2 a^-1) and the egg-parasitoids (21 +- 17 to 102 +- 33 ind. m^-2 a^-1) reached the highest densities. The biomass of the parasitic wasps ranged between 19 +- 5 (1981) and 170 +- 92 (1987) mg DW m^-2 a^-1 with a mean of 68 mg DW m^-2 a^-1. In comparison with other important insect taxa this is a low value.
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