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1.
Steen H  Mysterud A  Austrheim G 《Oecologia》2005,143(3):357-364
Inter-specific competition, facilitation and predation influence herbivore assemblages, but no study has experimentally explored the interactions between large ungulates and small rodents. In a fully replicated, landscape scale experiment, we manipulated densities of domestic sheep in mountain pastures in Norway. We then determined population growth and densities of rodents by live trapping in each of the areas with different sheep densities. We found that the (summer) population growth rate and autumn density of the field vole (Microtus agrestis) was lower at high sheep density. This provides the first experimental evidence of negative interactions between an ungulate and small rodent species. There was no effect on the bank vole (Clethrionomys glareolus), whose diet differs from sheep. Sheep density, therefore, potentially alters the pattern of inter-specific population synchrony amongst voles. Our study shows that negative interactions between large ungulates and small rodents may be species-specific and negative population consequences for the rodent population appear above threshold ungulate densities.Electronic supplementary material is available for this article at  相似文献   

2.
Emerging tick-borne diseases of humans and animals have occurred frequently during the past 30 years. These disease outbreaks appear to result from changes in the distribution of tick and vertebrate hosts, and the introduction of humans and domestic animals into tick–pathogen–wildlife cycles. Use of molecular technologies now available for identification of pathogens in ticks can provide valuable information that allows for risk analysis of emerging tick-borne diseases. In this study, the prevalence of selected pathogens in ticks collected in six locations in central Spain from the major wild ungulate species, European wild boar (Sus scrofa) and Iberian red deer (Cervus elaphus hispanicus), was determined by PCR. Tick species collected included Ixodes ricinus, Dermacentor marginatus, Rhipicephalus bursa and Hyalomma m. marginatum. Pathogens identified in ticks included piroplasmids, Anaplasma spp., Ehrlichia spp. and Rickettsia spp. Piroplasmids were identified in all tick species except I. ricinus. Ehrlichia spp. were detected in all tick species and collection locations, while Rickettsia spp., which proved to be R. slovaca and a recently identified Rickettsia sp. DnS28, were identified only in D. marginatus. A. marginale and A. phagocytophilum were detected in D. marginatus, R. bursa and Hy. m. marginatum. Concurrent infections of these pathogens were frequently observed in ticks. Notably, A. phagocytophilum, which is infective for a broad host range that includes humans and domestic and wild animals, was identified in ticks from all collection locations. The variety of ticks and tick-borne pathogens demonstrated in this study suggests a risk in central Spain for the emergence of tick-borne diseases in humans and domestic animals.  相似文献   

3.
半蓝角伪叶甲Cerogria basalis(Hope,1831)为角伪叶甲属Cerogria Borchmann,1909的1个大型种,过去仅知道分布于印度,尼泊尔,波斯尼亚和黑塞哥维那,一直缺乏详细和正式的形态描述。近年来,我们从云南采集到该种的雌虫和雄虫。本文对该种雌性和雄性成虫,特别是触角、腹板和雄性外生殖器特征作了详细描述。提供了该种雌、雄两性成虫的背面观和腹面观以及生境照片,以及触角、雄性末节腹板以及雄性外生殖器特征图片。本文还讨论了种内变异。这些工作为该种的正确鉴定提供了依据。  相似文献   

4.
Campylobacter,salmonella and chlamydia in free-living birds of Croatia   总被引:2,自引:0,他引:2  
Campylobacteriosis, salmonellosis and avian chlamydiosis are zoonotic diseases in which birds have been suggested to play an important role as reservoirs. We have investigated the prevalence of Campylobacter and Salmonella spp. and Chlamydophila sp. in 107 free-living birds belonging to 25 species from 13 families from Croatia in order to examine the natural infections caused by these agents. Campylobacter jejuni-like organisms were isolated from 2 of 107 free-living bird species examined (1.9%). Salmonella was isolated from 8 fresh fecal specimens from free-living bird species (7.4%). These isolates were identified as S. typhimurium in 4 (3.7%), and S. enteriditis in 4 (3.7%) free-living birds. These samples originated from feral pigeons (Columba livia domesticus; n=14; 28.6%), rook (Corvus frugilegus; n=13; 15.4%), buzzard (Buteo buteo; n=12; 16.7%), black-headed gull (Larus ridibundus; n=8; 12.5%) and tawny owl (Strix aluco; n=8; 12.5%). The presence of Chlamydophila sp. was not detected in the free-living birds examined during this study. Epidemiological aspects and possible significance of the examined birds as a source of infections for domestic animals and humans are discussed.  相似文献   

5.
We tested the effect of a large ungulate carcass on boreal forest biodiversity by contrasting the local abundance and diversity of Coleoptera around a roe deer Capreolus capreolus carcass and in a control plot, between 8 August and 3 September 2003, in southern Norway. The two plots differed both in occurrence and richness of species, which were almost double at the carcass plot, although the diversity indices were similar. The higher evenness of the control plot compensated for its lower number of species, probably because the carcass plot was a disturbed area, colonized by many species, which were represented by few individuals. The number of beetles captured each day correlated positively with temperature at the control plot, but not at the carcass plot, indicating that the presence of an abundant and concentrated resource increased the local activity of Coleoptera. The carcass is likely to create a particular microclimate, which could partly buffer against extremes of air-temperature variation. These preliminary results indicate that ungulate carcasses have a significant ecological impact, which should be further investigated to improve the management and restoration of European boreal forest ecosystems.  相似文献   

6.
[目的] 小条实蝇属害虫原产非洲,在我国无分布且具有一定的入侵风险。分析该虫在我国口岸的截获情况,能更好地利用已知实蝇截获数据防范实蝇人为传播。[方法] 经动植物检验检疫信息资源共享服务平台查询,统计小条实蝇属的有害生物类别、截获途径及截获地区等。[结果] 全国口岸共截获8种共计524批次的小条实蝇属害虫;地中海实蝇的截获批次数最多,为415批次,为小条实蝇属截获率的79.2%;截获的种类最多的国家来自尼日利亚,5种;截获批次最多的国家为南非,71批次;截获方式最多的为旅客携带物,占总批次的68.3%;在我国口岸中,广东口岸截获批次最多,占总数的57.4%。[结论] 从今后防控的重点种类、加大查验力度、推广新技术在鉴定上的应用、应急预案等几个方面,加强针对该类有害生物的检验检疫措施。  相似文献   

7.
The wild boar (Sus scrofa) is a medium-sized ungulate that produces a large variety of marks. Traditionally, wallowing is an activity that has fundamentally been related to several processes such as thermoregulation, reduction in the number of ectoparasites or disinfection of wounds in the skin of males resulting from fights to reach females. In this study, I analysed another possible function of wallowing in free-ranging wild boar populations when temperatures are low and parasitic numbers are not significant. The results indicate that during the sampling time, from October to February, the number of wild boars with a mud layer on their skin was 47, out of a total of 558 wild boar analysed. Of these 47 wild boars, 44 were males and within this group, 40 individuals were adult males. The wallowed males were bigger and older than non-wallowed males hunted at the same time. In addition, I found that males wallowed mainly during autumn (90.9% of all cases). In the total number of wild boars analysed, I did not notice individuals with wounds resulting from fights other than from the hunting day. On the other hand, the analysis of the females reproductive systems indicated that the rut period took place during the last days of October and the first days of November. From these results, the coincidence of the rut period with the maximum of wallowing in adult males could be indicative of a sexual function of this activity.  相似文献   

8.
The parasitoid complex of brown soft scale, Coccus hesperidum L., a multivoltine soft scale, was determined in southern California citrus over the period February 2004–March 2006. The survey was conducted by placing brown soft scale-infested yucca leaves in the canopy of citrus trees and subsequently rearing individually isolated parasitized scales in the laboratory. A total of 14 species parasitized brown soft scale in the field, the most abundant ones belonging to the genus Metaphycus Mercet (75%). The most abundant parasitoid species was Metaphycus angustifrons Compere (38% parasitism), and this is a new record of establishment for this species in California. Coccophagus species accounted for only 11% parasitism. There were important spatio-temporal differences across the parasitoid complex survey locations. We also found that the five most abundant encyrtid parasitoid species showed preferences for scales of different sizes. Our results have implications for biological control of citricola scale, Coccus pseudomagnoliarum (Kuwana), an important pest of citrus in the San Joaquin Valley of central California. Notably, this species is nearly absent in southern California. Brown soft scale is considered to be an alternate host for parasitoids of citricola scale, a univoltine soft scale, at times when the latter species is unavailable for parasitism.  相似文献   

9.
Bactrocera latifrons (Hendel) (Diptera: Tephritidae) is the most recent of four tephritid fruit fly species accidentally introduced into Hawaii. Although parasitoids have been released against other tephritid fruit fly species and have shown partial success in Hawaii, no parasitoids were released until 2004 to suppress populations of B. latifrons. The present study was conducted to document the parasitoid complex that has naturally established against B. latifrons in Hawaii and to assess whether there is a need for improving the biological control of this species. Based on ripe turkeyberry (Solanum torvum Sw) fruit collections over three consecutive years B. latifrons was the dominant tephritid fruit fly infestating turkeyberry at all four sites surveyed, across three major islands in Hawaii. The overall percentage parasitism of B. latifrons ranged from a low of 0.8% (Hana, Maui) to a high of 8.8% (Kahaluu, Oahu). Five primary parasitoid species were recovered from individually held B. latifrons puparia: Fopius arisanus (Sonan), Psyttalia incisi (Silvestri), Diachasmimorpha longicaudata (Ashmead), D. tryoni (Cameron), and Tetrastichus giffardianus Silvestri. F. arisanus was the predominant parasitoid at three of the four sites. Low levels of parasitism suggest that there is a need to improve biological control of B. latifrons, to minimize chances of this species causing economic impacts on crop production in Hawaii. We discuss the possibility of improving biological control of B. latifrons through augmentative releases of F. arisanus or introduction and release of specific and efficient new parasitoid species.  相似文献   

10.
Scirtothrips perseae Nakahara was discovered attacking avocados in California, USA, in 1996. Host plant surveys in California indicated that S. perseae has a highly restricted host range with larvae being found only on avocados, while adults were collected from 11 different plant species. As part of a management program for this pest, a “classical” biological control program was initiated and foreign exploration was conducted to delineate the home range of S. perseae, to survey for associated natural enemies and inventory other species of phytophagous thrips on avocados grown in Mexico, Guatemala, Costa Rica, the Dominican Republic, Trinidad, and Brazil. Foreign exploration efforts indicate that S. perseae occurs on avocados grown at high altitudes (>1500 m) from Uruapan in Mexico south to areas around Guatemala City in Guatemala. In Costa Rica, S. perseae is replaced by an undescribed congener as the dominant phytophagous thrips on avocados grown at high altitudes (>1300 m). No species of Scirtothrips were found on avocados in the Dominican Republic, Trinidad, or Brazil. In total, 2136 phytophagous thrips were collected and identified, representing over 47 identified species from at least 19 genera. The significance of these species records is discussed. Of collected material 4% were potential thrips biological control agents. Natural enemies were dominated by six genera of predatory thrips (Aeolothrips, Aleurodothrips, Franklinothrips, Leptothrips, Scolothrips, and Karnyothrips). One genus each of parasitoid (Ceranisus) and predatory mite (Balaustium) were found. Based on the results of our sampling techniques, prospects for the importation of thrips natural enemies for use in a “classical” biological control program in California against S. perseae are not promising.  相似文献   

11.
In consideration of their origin the adaptive strategies of the evergreen species of the Mediterranean maquis were analysed. Rosmarinus officinalis L., Erica arborea L., and Erica multiflora L. had the lowest net photosynthetic rate (PN) in the favourable period [7.8±0.6 mol(CO2) m–2s–1, mean value], the highest PN decrease (on an average 86 % of the maximum) but the highest recovery capacity (>70 % of the maximum) at the first rainfall in September. Cistus incanus L. and Arbutus unedo L. had the highest PN during the favourable period [15.5±5.2 mol(CO2) m–2s–1, mean value], 79 % decrease during drought, and a lower recovery capacity (on an average 54 %). Quercus ilex L., Phillyrea latifolia L., and Pistacia lentiscus L. had an intermediate PN in the favourable period [9.2±1.3 mol(CO2) m–2s–1, mean value], a lower reduction during drought (on an average 63 %), and a range from 62 % (Q. ilex and P. latifolia) to 39 % (P. lentiscus) of recovery capacity. The Mediterranean species had higher decrease in PN and stomatal conductance during drought and a higher recovery capacity than the pre-Mediterranean species. Among the pre-Mediterranean species, P. latifoliahad the best adaptation to long drought periods also by its higher leaf mass per area (LMA) which lowered leaf temperature thus decreasing transpiration rate during drought. Moreover, its leaf longevity determined a more stable leaf biomass during the year. Among the Mediteranean species, R. officinalis was the best adapted species to short drought periods by its ability to rapidly recover. Nevertheless, R. officinalis had the lowest tolerance to high temperatures by its PN dropping below half its maximum value when leaf temperature was over 33.6°C. R. officinalismay be used as a bioindicator species of global change.This revised version was published online in March 2005 with corrections to the page numbers.  相似文献   

12.
As part of a study carried out for detecting Arcobacter spp. in shellfish, three mussel isolates that were Gram-negative slightly curved rods, non-spore forming, showed a new 16S rDNA-RFLP pattern with a specific identification method for the species of this genus. Sequences of the 16S rRNA gene and those of the housekeeping genes rpoB, gyrB and hsp60 provided evidence that these mussel strains belonged to an unknown genetic lineage within the genus Arcobacter. The similarity between the 16S rRNA gene sequence of the representative strain (F79-6T) and type strains of the other Arcobacter species ranged between 94.1% with A. halophilus and 99.1% with the recently proposed species A. defluvii (CECT 7697T). DDH results between strain F79-6T and the type strain of the latter species were below 70% (53 ± 3.0%). Phenotypic characteristics together with MALDITOF mass spectra differentiated the new mussel strains from all other Arcobacter species. All the results indicate that these strains represent a new species, for which the name Arcobacter ellisii sp. nov. with the type strain F79-6T (=CECT 7837T = LMG 26155T) is proposed.  相似文献   

13.
We conducted a field survey for flatworms to select species as potential biological control agents against Aedes aegypti and Culex pipiens (Diptera, Culicidae) breeding in artificial containers. Laboratory experiments were performed to determine the daily predation rate, differential predation on each mosquito larval instar, selective predation on either A. aegypti or C. pipiens, and predator tolerance to water from artificial containers. Girardia anceps (Tricladida, Paludicola, Dugesiidae), Mesostoma ehrenbergii and Bothromesostoma cf. evelinae (Rhabdocoela, Typhloplanoida, Typhloplanidae) were found in temporary puddles and permanent pools. In the laboratory, they killed between 52% and 100% of immature mosquitoes coexisting in the same habitat. No preference of flatworms for mosquito preys was detected. Predation rate was related to predator size and instar of preys. Girardia anceps and B. evelinae survived after a dry period and when re-flooding occurred, they laid eggs. Tolerance to water from artificial containers was highest in G. anceps and this species could be a suitable predator to reduce mosquito populations from artificial containers using an inoculative approach.  相似文献   

14.
Tinea Nigra: Report of Twelve Cases in Venezuela   总被引:1,自引:0,他引:1  
Tinea nigra is a superficial mycotic infection produced by Hortaea werneckii, formerly known as Phaeoannelomyces werneckii, formerly known as Exophiala werneckii, and Stenella araguata, the latter autochthonous in Venezuela, it was first described and named as Cladosporium castellanii in 1973. The present report describes 12 cases in the period of 1972–2002, diagnosed at the Medical Mycology Section at the Tropical Institute of the Universidad Central de Venezuela, in Caracas. This mycosis is more prevalent among young people, with fair skin, from 3 to 28 years of age, who visited beaches and in whom the lesions are more evident. Out of these 12 patients, 8 (66.66%) had Phaeoannelomyces werneckii as the causal agent and 2 (16.67%) Stenella araguata was isolated. Two patients had more than one macule, and curiously in these cases, each lesion was caused by a different species of the aforementioned fungus.  相似文献   

15.
The aim of this study is to compare the recovery dynamics in three shrub communities subjected to experimental burning and cutting, and situated on an altitudinal gradient. Climatic features are different in each area, but all had the common characteristic of very homogeneous vegetation cover before the disturbances, with only one shrub species clearly dominant, a different taxon in each area, and with different regeneration strategies. The first area was a heathland dominated by Calluna vulgaris, situated at an altitude of 1600 m, with a continental climate (mean annual precipitation 1320 mm). The second area was a heathland dominated by Erica australis, located at an altitude of 1000 m (mean annual precipitation 840 mm). The third area was a Cistus ladanifer shrubland, located at 900 m altitude, with a Mediterranean climate similar to that of the previous area, but with lower mean annual precipitation (470 mm). Erica australis recovers by vegetative resprouting, but Cistus ladanifer is an obligate seeder, as is Calluna vulgaris in these areas. Each experimental disturbance was carried out over 100 m2 in each area. Post-fire recovery is faster in Cistus ladanifer: 2 years after burning there was 40% cover vs. less than 20% in the other two species. However, recovery after cutting was similar for Cistus ladanifer and Erica australis. Calluna vulgaris recovers very slowly, with cover values below 20% even 10 years after both disturbances. Cover of dominant shrub species is negatively correlated with cover of herbaceous species. So different recovery of dominant species lead a different community dynamic in each area.  相似文献   

16.
The question of the degree of evolutionary conservation of the pair-rule patterning mechanism known from Drosophila is still contentious. We have employed chromophore-assisted laser inactivation (CALI) to inactivate the function of the pair-rule gene even skipped (eve) in the short germ embryo of the flour beetle Tribolium. We show that it is possible to generate pair-rule type phenocopies with defects in alternating segments. Interestingly, we find the defects in odd numbered segments and not in even numbered ones as in Drosophila. However, this apparent discrepancy can be explained if one takes into account that the primary action of eve is at the level of parasegments and that different cuticular markers are used for defining the segment borders in the two species. In this light, we find that eve appears to be required for the formation of the anterior borders of the same odd numbered parasegments in both species. We conclude that the primary function of eve as a pair rule gene is conserved between the two species.  相似文献   

17.
Productive tundra plant communities composed of a variety of fast growing herbaceous and woody plants are likely to attract mammalian herbivores. Such vegetation is likely to respond to different-sized herbivores more rapidly than currently acknowledged from the tundra. Accentuated by currently changing populations of arctic mammals there is a need to understand impacts of different-sized herbivores on the dynamics of productive tundra plant communities. Here we assess the differential effects of ungulate (reindeer) and small rodent herbivores (voles and lemmings) on high productive tundra vegetation. A spatially extensive exclosure experiment was run for three years on river sediment plains along two river catchments in low-arctic Norway. The river catchments were similar in species pools but differed in species abundance composition of both plants and vertebrate herbivores. Biomass of forbs, deciduous shrubs and silica-poor grasses increased by 40–50% in response to release from herbivory, whereas biomass of silica-rich grasses decreased by 50–75%. Hence both additive and compensatory effects of small rodents and reindeer exclusion caused these significant changes in abundance composition of the plant communities. Changes were also rapid, evident after only one growing season, and are among the fastest and strongest ever documented in Arctic vegetation. The rate of changes indicates a tight link between the dynamics of productive tundra vegetation and both small and large herbivores. Responses were however not spatially consistent, being highly different between the catchments. We conclude that despite similar species pools, variation in plant species abundance and herbivore species dynamics give different prerequisites for change.  相似文献   

18.
Species of Apiognomonia with their Discula anamorphic states in the Gnomoniaceae, Diaporthales, are known throughout the temperate Northern Hemisphere and cause diseases such as sycamore or plane tree anthracnose. The genus Apiognomonia was described based on A. veneta as the type species; however, there has been disagreement about whether or not A. veneta is a synonym of A. errabunda. Using morphological, ecological, and DNA sequence data we conclude that A. errabunda and A. veneta are different species, although very closely related; thus, A. veneta is the correct name for the type species of Apiognomonia. This conclusion is based on a combined analysis of sequences from the ITS regions of nuclear rDNA for 51 isolates from host plants of eight genera and intron regions from actin, calmodulin and translation elongation factor 1-alpha for over 25 isolates. The type species of the genus Discula is D. nervisequa, the earliest available epithet for D. platani, the lectotype of Discula. D. nervisequa is the anamorph of A. veneta. Based on an examination of the type specimen, we determined that the commonly used name for the anamorph of A. errabunda, D. umbrinella, refers to another species. A. veneta and A. errabunda including their anamorphs are described and illustrated. An account of all synonyms and excluded synonyms is presented.  相似文献   

19.
Taenia tapeworms of Finnish and Swedish wolves (Canis lupus) and Finnish brown bears (Ursus arctos), and muscle cysticerci of Svalbard reindeer (Rangifer tarandus platyrhynchus), Alaskan Grant's caribou (Rangifer tarandus granti) and Alaskan moose (Alces americanus) were identified on the basis of the nucleotide sequence of a 396 bp region of the mitochondrial cytochrome c oxidase subunit 1 gene. Two species were found from wolves: Taenia hydatigena and Taenia krabbei. The cysticerci of reindeer, caribou and one moose also represented T. krabbei. Most of the cysticercal specimens from Alaskan moose, however, belonged to an unknown T. krabbei-like species, which had been reported previously from Eurasian elks (Alces alces) from Finland. Strobilate stages from two bears belonged to this species as well. The present results suggest that this novel Taenia sp. has a Holarctic distribution and uses Alces spp. as intermediate and ursids as final hosts.  相似文献   

20.
To identify the animal sources for Cryptosporidium and Giardia contamination, we genotyped Cryptosporidium and Giardia spp. in wildlife from Sydney’s water catchments using sequence analysis at the 18S rRNA locus for Cryptosporidium and 18S rRNA and glutamate dehydrogenase (gdh) for Giardia. A total of 564 faecal samples from 16 different host species were analysed. Cryptosporidium was identified in 8.5% (48/564) samples from eight host species and Giardia was identified in 13.8% (78/564) from seven host species. Eight species/genotypes of Cryptosporidium were identified. Five G. duodenalis assemblages were detected including the zoonotic assemblages A and B.  相似文献   

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