排序方式: 共有6条查询结果,搜索用时 0 毫秒
1
1.
We compared the aquatic metazoan community structure in bamboo stumps between a lowland (Kosinggolan; 200 m a.s.l.) and a
highland site (Moat; 1030–1050 m a.s.l.) in North Sulawesi. The lowland bamboo stumps harbored 38 taxa including 2 predators,
and the highland stumps harbored 35 taxa including 2 predators. In total 45 taxa were recorded, including 3 predators. Dominant
detritivores were Tipulidae, Scirtidae, Chironomidae, Culicidae and Ceratopogonidae. The sole dominant predators wereToxorhynchites mosquito larvae, which occurred in 67% and 28% of stumps at the lowland and the highland sites, respectively. Although the
mean biomass per stump did not differ significantly between the sites, the mean number of species per stump was significantly
smaller at the lowland site. In addition, the variation in species composition among stumps was greater at the lowland site
than at the highland site. Among dominant taxonomic groups, the number of non-predatory culicid species per stump was smaller
at the lowland site where their predator,Toxorhynchites, was more abundant, although both sites had the same number of culicid species. In the presence ofToxorhynchites, the density and biomass of other culicids per stump were reduced significantly. The difference in predator density might
affect differences in the local-scale community structure of individual bamboo stumps. 相似文献
2.
Habitat stability and the larval mosquito community in treeholes and other containers on a temperate Island 总被引:3,自引:0,他引:3
The temporal fluctuation of water levels and the presence of mosquito larvae were investigated for four types of small container
habitats (treeholes, bamboo stumps, cemetery stone vases, and cemetery stone vessels) on Kabeshima Island in Kyushu, southwestern
Japan. The probability that containers held water was positively correlated with the quantity of the preceding rainfall and
with the depth and volume of the containers. It was estimated that dehydration occurred more regularly in autumn and winter
than in summer. The probability that mosquito larvae were present in each type of container was positively correlated with
habitat stability in terms of the probability of the existence of standing water and the coefficient of variation of the water
level. Twelve species of mosquito larvae, including two rare predators, were found. Species composition differed between the
different types of container. Although 4 to 10 species used each type of container, the median number of species per container
was two for treeholes and bamboo stumps, and one for the others. The dominant species wasTripteroides bambusa in treeholes and bamboo stumps,Aedes albopictus in stone vases, andA. japonicus in stone vessels. The larval mosquito community, which lacked major predators, possessed the following features that may
facilitate the coexistence of many species: (1) niche segregation amongst species in terms of their selection of container
types; (2) an aggregated distribution of the individual species among containers of the same type; (3) high intraspecific
mean crowding (and hence probably intense intraspecific competition) in the dominant species in each type of container; (4)
independent species associations within the same type of container; and (5) low interspecific mean crowding (and hence probablynot intense interspecific competition) between species in the same type of container. 相似文献
3.
Mechanisms allowing the persistence of an aquatic predator-prey system in tiny pools (the mean ca. 0.5 ml) held by taro axils
were analyzed from the viewpoint of temporal and spatial patterns of habitat use. Predatory larvae of a mosquitoTopomyia tipuliformis concentrated in young axils, while 9 other taxa utilized both young and old axils or concentrated more in older axils. The
total prey density was lower in axils with the predator but the density of each prey taxon (except for a few cases) and the
number of prey taxa did not differ between axils with and without predators. This indicates thatT. tipuliformis is a general predator and does not influence prey community organization through selective removal of particular prey taxa.
Inter-axil distribution ofT. tipuliformis was aggregated in the first instar but uniform in the third and fourth instars due to intraspecific cannibalism, which assures
the survival of a single individual under short food supply. Distributions of prey taxa were mostly aggregated, fitting the
negative binomial distribution. Thirty seven out of 45 associations of 10 taxa were independent with 3 negative (between the
predator and some late-colonizing prey) and 5 positive (between some prey taxa) associations. Probabilistic refuges (produced
by independent aggregated distributions) reduced interspecific encounters which may result in competition and predation, and
thus probably facilitated prey coexistence. There was no evidence for the importance of predation in structuring the prey
community. This system may be prey-dominated in that predator persistence depends on prey community existence but prey community
structure depends less on predation. 相似文献
4.
We studied seasonal changes in the larval population structure, adult size, and autogeny (egg production without a bloodmeal)
of the mosquitoAedes togoi on the seacoast of northern Kyushu, Japan. The effects of temperature, photoperiod and food conditions on larval development,
adult size and autogeny were studied in the laboratory.Aedes togoi overwintered in both the egg and larval stages and was multivoltine. Adult size was greater in spring and autumn and smaller
in summer. Autogeny occurred in spring and autumn but not in summer. Autogenous females were larger than anautogenous females,
and larger autogenous females produced more eggs. Laboratory experiments showed that autogeny was promoted under low temperature
and short-day conditions which corresponded with spring/autumn conditions in the field. Experimental food limitation in the
larval stage greatly reduced adult size and autogenous egg production. In the field, large inter-pool variations in adult
size and autogeny rate probably resulted from variations in nutrient and crowding conditions. Seasonal autogeny ofAedes togoi was discussed in terms of life-history strategy under fluctuating environmental conditions where relative advantages of autogenous
and anautogenous reproduction alternate seasonally. 相似文献
5.
Summary Factors influencing development and survival ofCulex pipiens pallens immatures in polluted urban creeks were studied in Saga, Japan. Addition of food shortened developmental durations and increased
pupal size in floating cages at only the least polluted site out of 4 study sites. There was no evidence for developmental
delay due to overcrowding in natural populations. Survival was not increased by artificial feeding at any site. Using the
developmental parameters obtained for caged cohorts, survival in natural populations was estimated from differences between
the actual number and the expectation if there were no mortality. Pupation rates ranged from 1> to >10% by site and season.
Mortality due to predation, evaluated from the difference in pupation rates between caged and natural populations, exceeded
30% in 4 out of 6 cases (twice at 2 sites and once at the other 2 sites). Lethal factors in the creek water caused the predominant
mortality in 2 other cases. Regulation ofC. pipiens pallens population breeding in eutrophic, open creeks was discussed in the context of larval dispersal through behavioral interference. 相似文献
6.
Journal of Population Research - By late January 2020, the 2019 novel coronavirus (SARS-CoV-2) had reached Europe and most European countries had registered cases by March 1. However, the spread of... 相似文献
1