Feeding Ecology Informs Parasite Epidemiology: Prey Selection Modulates Encounter Rate with Echinococcus multilocularis in Urban Coyotes

We investigated the role of urban coyote feeding ecology in the transmission of Echinococcus multilocularis, the causative agent of Alveolar Echinococcosis in humans. As coyotes can play a main role in the maintenance of this zoonotic parasite within North American urban settings, such study can ultimately aid disease risk management. Between June 2012 and June 2013, we collected 251 coyote feces and conducted trapping of small mammals (n = 971) in five parks in the city of Calgary, Alberta, Canada. We investigated E. multilocularis epidemiology by assessing seasonal variations of coyote diet and the selective consumption of different rodent intermediate host species. Furthermore, accounting for small mammal digestibility and coyote defecation rates we estimated the number of small mammal preys ingested by coyote and consequently, coyote encounter rates with the parasite. Dominant food items included small mammals, fruit and vegetation, although hare and deer were seasonally relevant. The lowest frequency of occurrence per scat of small mammals was recorded in winter (39.4 %), when consumption of deer was highest (36.4 %). However, highest encounter rates (number of infected hosts predated/season) with E. multilocularis (95% CI: 1.0 - 22.4), combined with the lack of predation on non-competent small mammal species, suggest that winter is the critical season for transmission and control of this parasite. Within the small mammal assemblage, voles (Microtus pennsylvanicus and Myodes gapperi) were the selected preys of urban coyotes and likely played a key role for the maintenance of the urban sylvatic life-cycle of E. multilocularis in Calgary.     

Food, Feeding Behavior and Feeding Ecology of Nemerteans

The feeding biology of nemerteans is reviewed, new informationis presented, and the role of nemerteans in natural communitiesis discussed and evaluated. Most nemerteans are carnivorous,the majority feeding on live, often specific, prey, while someare scavengers. Macrophagous feeding is found in the Palaeonemertea,Heteronemertea and some of the Hoplonemertea; the more specializedsuctorial feeding is limited to five of the hoplonemertean families,and suspension feeding (omnivorous diet) occurs only in thehighly specialized symbiotic monogeneric Bdellonemertea. Feeding adaptations seem to be related to the nature and employmentof the proboscis, the dilatability of the mouth, and the structureof the anterior part of the digestive tract. The transport ofdissolved organic materials from seawater has been demonstrated,but its role in nemertean nutrition is just being contemplated.Present meager information on predation has shown nemerteansto have actually and potentially large effects on prey populationsand thus on the communities in which they live. As the feedingbiology of only a relative handful of species has been studied,much basic comparative research is needed before we can corroborateor refute our present ideas concerning the ecological rolesof nemerteans.     

Feeding Ecology and Dietary Flexibility of <Emphasis Type="Italic">Colobus angolensis palliatus</Emphasis> in Relation to Habitat Disturbance

Behavioral and dietary flexibility permits primates to survive in variable environments. It is clear that some species cope with habitat disturbance and fragmentation better than others. I examined the dietary flexibility of Colobus angolensis palliatus by studying three groups inhabiting structurally distinct ranges in Kenya’s Diani Forest. I predicted that the two groups inhabiting more disturbed areas would have reduced food availability and would respond by increasing dietary diversity and consuming greater proportions of lianas and exotic plant species compared to the group inhabiting the more intact area. Forest composition and overall plant part availability differed among home ranges; however, group diets did not differ in their proportions of different plant parts, nor did groups select plant parts in proportion to their availability. Diets differed dramatically with regard to species-specific plant parts, i.e., mean monthly dietary overlap among groups = 10.4%. Contrary to my predictions, all three groups exhibited considerable dietary diversity, i.e., 63–76 plant species, and relied heavily on lianas, i.e., 20.8–38.4% of the diet, and exotic plant species, i.e., 30.1–40.3% of the diet. The presence of exotic plant species in all three ranges suggests that even the most intact areas of the Diani Forest are perturbed and should be classified along a spectrum of habitat disturbance rather than intact vs. degraded. Nonetheless, this study emphasizes that diets can vary considerably among groups living in the same forest, and this degree of dietary flexibility likely enables C. a. palliatus to survive within increasingly disturbed habitats.     

Food and Feeding Ecology of Puffins

This study shows that although annual fluctuations occur in the main prey types of Skomer Puffins, food availability does not appear to limit breeding success. Most birds found food close to the colony, showing peaks of activity early in the day and again in late afternoon; and two out of four experimental pairs were able to rear 'twins', though the growth-rates of these were less than for single chicks. Some interesting observations are given on the feeding of the chick and on kleptoparasitism of adults by Jackdaws and gulls.     

Niche Partitioning of Feather Mites within a Seabird Host, Calonectris borealis

According to classic niche theory, species can coexist in heterogeneous environments by reducing interspecific competition via niche partitioning, e.g. trophic or spatial partitioning. However, support for the role of competition on niche partitioning remains controversial. Here, we tested for spatial and trophic partitioning in feather mites, a diverse and abundant group of arthropods. We focused on the two dominant mite species, Microspalax brevipes and Zachvatkinia ovata, inhabiting flight feathers of the Cory’s shearwater, Calonectris borealis. We performed mite counts across and within primary and tail feathers on free-living shearwaters breeding on an oceanic island (Gran Canaria, Canary Islands). We then investigated trophic relationships between the two mite species and the host using stable isotope analyses of carbon and nitrogen on mite tissues and potential host food sources. The distribution of the two mite species showed clear spatial segregation among feathers; M. brevipes showed high preference for the central wing primary feathers, whereas Z. ovata was restricted to the two outermost primaries. Morphological differences between M. brevipes and Z. ovata support an adaptive basis for the spatial segregation of the two mite species. However, the two mites overlap in some central primaries and statistical modeling showed that Z. ovata tends to outcompete M. brevipes. Isotopic analyses indicated similar isotopic values for the two mite species and a strong correlation in carbon signatures between mites inhabiting the same individual host suggesting that diet is mainly based on shared host-associated resources. Among the four candidate tissues examined (blood, feather remains, skin remains and preen gland oil), we conclude that the diet is most likely dominated by preen gland oil, while the contribution of exogenous material to mite diets is less marked. Our results indicate that ongoing competition for space and resources plays a central role in structuring feather mite communities. They also illustrate that symbiotic infracommunities are excellent model systems to study trophic ecology, and can improve our understanding of mechanisms of niche differentiation and species coexistence.     

鹊鸲冬季和春季取食生态位初步研究

2013年3—5月,2014年12月—2015年2月,在广西宜州利用直接观察法对鹊鸲Copsychus saularis的取食生态位进行分析,记录鹊鸲的数量、取食时间、食物种类、取食方式、取食生态位、取食方向等,共记录38 d,收集数据6 407个。结果表明:鹊鸲为杂食性鸟类,以果实和昆虫为主,冬季取食的植物有23种,取食生态位宽度为11.24;春季取食植物有22种,取食生态位宽度为12.19;春季和冬季的取食生态位重叠度为0.359。卡方独立性检验表明:春季和冬季鹊鸲的取食时间和食物种类的差异有统计学意义(P0.05);取食高度、取食水平和取食方向等的差异无统计学意义(P0.05)。鹊鸲的取食方式为啄食。鹊鸲的食物种类和取食时间受季节的影响较大,人为干扰是影响鹊鸲取食和活动的主要因素。     

暗绿绣眼鸟春季和冬季取食生态位初步研究

2014年10—12月和2015年3—5月在广西壮族自治区宜州市对暗绿绣眼鸟Zosterops japonicus春季和冬季的取食空间生态位进行了研究,主要记录暗绿绣眼鸟的数量、取食时段、食物种类以及包括取食高度、水平取食位置、取食方向等相关取食行为数据。结果表明,暗绿绣眼鸟为杂食性鸟类,主要采食植物嫩叶、果实,偶尔采食昆虫或花瓣。春季取食的植物有31种,食物生态位宽度为13.86;冬季取食的植物有21种,食物生态位宽度为11.75;春季和冬季的食物生态位重叠度为0.903。春季暗绿绣眼鸟在06∶00—09∶00取食频次最高(占42.93%),而冬季则是在09∶00—12∶00取食频次最高(占38.04%)。卡方独立性检验表明:春季和冬季暗绿绣眼鸟在取食时间和取食高度上的差异均有统计学意义(P0.05),在水平取食位置和取食方向上的差异无统计学意义(P0.05)。     

Feeding Ecology of <Emphasis Type=Italic>Trachypithecus pileatus</Emphasis> in India

We observed a group of capped langurs for 12 mo in the Pakhui Wildlife Sanctuary, Arunachal Pradesh, India. We recorded the time of feeding on different food plant species, food categories, and the feeding heights of monkeys in trees. Capped langurs spent 68% of their feeding time on leaves, 16% on flowers, and 16% on fruits. Feeding on leaves was consistently high (p < 0.01) during the year, with the highest feeding in May (85%) and the lowest in January (47%). The seasonal difference in feeding on leaves is significant (p < 0.05): it was higher in summer and during monsoon. The feeding time on flowers was maximal (35%) in March and that on fruits and seeds was minimal (38%) in January. Langurs ate 52 plant species throughout the year. The largest number of plants (6) were species of Moraceae, and langurs spent more feeding time (20%) on them alone. The number of plants eaten per month varied significantly (p < 0.05). Langurs ate Gmelina arborea, Albizzia lucida, Ficus glomereta, and Makania micrantha throughout the year. They spent 44% of their feeding time in terminal canopies and their average feeding height was 30–35 m. This is the first study to examine the feeding ecology of capped langurs and provides baseline data for the species.     

Dietary Cholesterol Modulates Pathogen Blocking by Wolbachia

The bacterial endosymbiont Wolbachia pipientis protects its hosts from a range of pathogens by limiting their ability to form infections inside the insect. This “pathogen blocking” could be explained by innate immune priming by the symbiont, competition for host-derived resources between pathogens and Wolbachia, or the direct modification of the cell or cellular environment by Wolbachia. Recent comparative work in Drosophila and the mosquito Aedes aegypti has shown that an immune response is not required for pathogen blocking, implying that there must be an additional component to the mechanism. Here we have examined the involvement of cholesterol in pathogen blocking using a system of dietary manipulation in Drosophila melanogaster in combination with challenge by Drosophila C virus (DCV), a common fly pathogen. We observed that flies reared on cholesterol-enriched diets infected with the Wolbachia strains wMelPop and wMelCS exhibited reduced pathogen blocking, with viral-induced mortality occurring 2–5 days earlier than flies reared on Standard diet. This shift toward greater virulence in the presence of cholesterol also corresponded to higher viral copy numbers in the host. Interestingly, an increase in dietary cholesterol did not have an effect on Wolbachia density except in one case, but this did not directly affect the strength of pathogen blocking. Our results indicate that host cholesterol levels are involved with the ability of Wolbachia-infected flies to resist DCV infections, suggesting that cholesterol contributes to the underlying mechanism of pathogen blocking.     

Host Range and Ecology of Isolates of Pasteuria spp. from the Southeastern United States

Isolates of Pasteuria penetrans were evaluated for ecological characteristics that are important in determining their potential as biological control agents. Isolate P-20 survived without loss of its ability to attach to its host nematode in dry, moist, and wet soil and in soil wetted and dried repeatedly for 6 weeks. Some spores moved 6.4 cm (the maximum distance tested) downward in soil within 3 days with percolating water. The isolates varied greatly in their attachment to different nematode species and genera. Of five isolates tested in spore-infested soil, three (P-104, P-122, B-3) attached to two or more nematode species, whereas B-8 attached only to Meloidogyne hapla and B-I did not attach to any of the nematodes tested. In water suspensions, spores of isolate P-20 attached readily to M. arenaria but only a few spores attached to other Meloidogyne spp. Isolate P-104 attached to all Meloidogyne spp. tested but not to Pratylenchus scribneri. Isolate B-4 attached to all species of Meloidogyne and Pratylenchus tested, but the rate of attachment was relatively low. Isolate P-Z00 attached in high numbers to M. arenaria when spores were extracted from females of this nematode; when extracted from M. javanica females, fewer spores attached to M. arenaria than to M. javanica or M. incognita.     

A Major Role for Mammals in the Ecology of Mycobacterium ulcerans

Background

Mycobacterium ulcerans is the causative agent of Buruli ulcer (BU), a destructive skin disease found predominantly in sub-Saharan Africa and south-eastern Australia. The precise mode(s) of transmission and environmental reservoir(s) remain unknown, but several studies have explored the role of aquatic invertebrate species. The purpose of this study was to investigate the environmental distribution of M. ulcerans in south-eastern Australia.

Methodology/Principal Findings

A range of environmental samples was collected from Point Lonsdale (a small coastal town southwest of Melbourne, Australia, endemic for BU) and from areas with fewer or no reported incident cases of BU. Mycobacterium ulcerans DNA was detected at low levels by real-time PCR in soil, sediment, water residue, aquatic plant biofilm and terrestrial vegetation collected in Point Lonsdale. Higher levels of M. ulcerans DNA were detected in the faeces of common ringtail (Pseudocheirus peregrinus) and common brushtail (Trichosurus vulpecula) possums. Systematic testing of possum faeces revealed that M. ulcerans DNA could be detected in 41% of faecal samples collected in Point Lonsdale compared with less than 1% of faecal samples collected from non-endemic areas (p<0.0001). Capture and clinical examination of live possums in Point Lonsdale validated the accuracy of the predictive value of the faecal surveys by revealing that 38% of ringtail possums and 24% of brushtail possums had laboratory-confirmed M. ulcerans skin lesions and/or M. ulcerans PCR positive faeces. Whole genome sequencing revealed an extremely close genetic relationship between human and possum M. ulcerans isolates.

Conclusions/Significance

The prevailing wisdom is that M. ulcerans is an aquatic pathogen and that BU is acquired by contact with certain aquatic environments (swamps, slow-flowing water). Now, after 70 years of research, we propose a transmission model for BU in which terrestrial mammals are implicated as reservoirs for M. ulcerans.     

韩江下游底栖动物的分布及其对水质的评价

韩江下游底栖动物的分布及其对水质的评价蓝宗辉（韩山师范学院生物系,广东潮州５２１０４１）ＴｈｅＺｏｏｂｅｎｔｈｏｓＤｉｓｔｒｉｂｕｔｉｏｎｉｎｔｈｅＬｏｗｅｒＲｅａｃｈｅｓｏｆＨａｎｊｉａｎｇＲｉｖｅｒａｎｄＡｓｅｓｍｅｎｔｏｆｉｔｓＷａｔｅｒＱｕａ...     

The Ecology of Microbial Communities Associated with Macrocystis pyrifera

Kelp forests are characterized by high biodiversity and productivity, and the cycling of kelp-produced carbon is a vital process in this ecosystem. Although bacteria are assumed to play a major role in kelp forest carbon cycling, knowledge of the composition and diversity of these bacterial communities is lacking. Bacterial communities on the surface of Macrocystis pyrifera and adjacent seawater were sampled at the Hopkins Marine Station in Monterey Bay, CA, and further studied using 454-tag pyrosequencing of 16S RNA genes. Our results suggest that M. pyrifera-dominated kelp forests harbor distinct microbial communities that vary temporally. The distribution of sequence tags assigned to Gammaproteobacteria, Alphaproteobacteria and Bacteriodetes differed between the surface of the kelp and the surrounding water. Several abundant Rhodobacteraceae, uncultivated Gammaproteobacteria and Bacteriodetes-associated tags displayed considerable temporal variation, often with similar trends in the seawater and the surface of the kelp. Bacterial community structure and membership correlated with the kelp surface serving as host, and varied over time. Several kelp-specific taxa were highly similar to other bacteria known to either prevent the colonization of eukaryotic larvae or exhibit antibacterial activities. Some of these kelp-specific bacterial associations might play an important role for M. pyrifera. This study provides the first assessment of the diversity and phylogenetic profile of the bacterial communities associated with M. pyrifera.     

白头鹎春季食性及取食空间生态位的初步研究

2004年2月11日~6月10日,用直接观察法中的随机取样法和扫描取样法,对四川南充市及郊区(北纬30°41′~30°51′,东经106°01′~106°07′)白头鹎的食性和取食空间生态位进行了研究。结果显示:白头鹎为杂食性鸟类,主要在乔木树冠、灌丛、菜地、草地和空中取食约30种植物的芽、嫩叶、花、花蜜、果实及昆虫。在育雏以前以植物性食物为主,动物性食物的频次仅占食物总频次的1.77%。育雏时,其捕食动物性食物的频次占食物总频次的55%。     

Vertical Movement Patterns and Ontogenetic Niche Expansion in the Tiger Shark,Galeocerdo cuvier

Sharks are top predators in many marine ecosystems and can impact community dynamics, yet many shark populations are undergoing severe declines primarily due to overfishing. Obtaining species-specific knowledge on shark spatial ecology is important to implement adequate management strategies for the effective conservation of these taxa. This is particularly relevant concerning highly-mobile species that use wide home ranges comprising coastal and oceanic habitats, such as tiger sharks, Galeocerdo cuvier. We deployed satellite tags in 20 juvenile tiger sharks off northeastern Brazil to assess the effect of intrinsic and extrinsic factors on depth and temperature usage. Sharks were tracked for a total of 1184 d and used waters up to 1112 m in depth. The minimum temperature recorded equaled 4°C. All sharks had a clear preference for surface (< 5 m) waters but variability in depth usage was observed as some sharks used mostly shallow (< 60 m) waters whereas others made frequent incursions into greater depths. A diel behavioral shift was detected, with sharks spending considerably more time in surface (< 10 m) waters during the night. Moreover, a clear ontogenetic expansion in the vertical range of tiger shark habitat was observed, with generalized linear models estimating a ~4-fold increase in maximum diving depth from 150- to 300-cm size-classes. The time spent in the upper 5 m of the water column did not vary ontogenetically but shark size was the most important factor explaining the utilization of deeper water layers. Young-of-the-year tiger sharks seem to associate with shallow, neritic habitats but they progressively move into deeper oceanic habitats as they grow larger. Such an early plasticity in habitat use could endow tiger sharks with access to previously unavailable prey, thus contributing to a wider ecological niche.     

Feeding Ecology of the Allochthonous Feeder Rasbora daniconius (HAMILTON) (Cyprinidae – Teleostei)

Seasonal fluctuations in the dietary components of Rasbora daniconius inhabiting a perennial eutrophic pond have been studied on the basis of analyses of the gut contents over a period of one year from 1980 to 1981. Modified Points method was adopted for the quantitative estimation of the dietary items. Gut analysis revealed that the fish is predominantly an allochthonous feeder subsisting mainly on terrestrial Hymenoptera and Coleoptera. Flowers and seeds also formed part of the dietary composition of the fish. Allochthonous fauna were preferred at all the stages of the growth of the fish. Females have a greater preference for terrestrial Coleoptera and the males for Formicidae. The feeding intensities of three different length groups and both sexes were also ascertained. This revealed that June, July, October and November are the most intensive feeding periods of R. daniconius. Older and mature fishes were found to be more active feeders than juveniles.     

A Dietary Test of Putative Deleterious Sterols for the Aphid Myzus persicae

The aphid Myzus persicae displays high mortality on tobacco plants bearing a transgene which results in the accumulation of the ketosteroids cholestan-3-one and cholest-4-en-3-one in the phloem sap. To test whether the ketosteroids are the basis of the plant resistance to the aphids, M. persicae were reared on chemically-defined diets with different steroid contents at 0.1–10 µg ml⁻¹. Relative to sterol-free diet and dietary supplements of the two ketosteroids and two phytosterols, dietary cholesterol significantly extended aphid lifespan and increased fecundity at one or more dietary concentrations tested. Median lifespan was 50% lower on the diet supplemented with cholest-4-en-3-one than on the cholesterol-supplemented diet. Aphid feeding rate did not vary significantly across the treatments, indicative of no anti-feedant effect of any sterol/steroid. Aphids reared on diets containing equal amounts of cholesterol and cholest-4-en-3-one showed fecundity equivalent to aphids on diets containing only cholesterol. Aphids were reared on diets that reproduced the relative steroid abundance in the phloem sap of the control and modified tobacco plants, and their performance on the two diet formulations was broadly equivalent. We conclude that, at the concentrations tested, plant ketosteroids support weaker aphid performance than cholesterol, but do not cause acute toxicity to the aphids. In plants, the ketosteroids may act synergistically with plant factors absent from artificial diets but are unlikely to be solely responsible for resistance of modified tobacco plants.     

Feeding Ecology of <Emphasis Type=Italic>Propithecus diadema</Emphasis> in Forest Fragments and Continuous Forest

Forest fragmentation is viewed as a serious threat to primates, yet whether or not it can disrupt food resources and cause energetic stress remains largely untested. I present the results of a 12-mo study of the feeding ecology of Propithecus diadema in fragmented and continuous forest at Tsinjoarivo, eastern Madagascar. Two continuous forest groups had higher dietary diversity and ate more fleshy fruit, but during the dry season, diversity was reduced and they relied heavily on mistletoe (Bakerella clavata). In contrast, 2 groups in fragments employed the lean season strategy of eating mistletoe year-round; the fruiting tree species that sustain continuous forest groups through the rainy season were largely absent. As expected, intersite dietary overlap was highest in the dry season. The level of specialization was high: fragment groups devoted 30–40% of feeding time to Bakerella clavata, compared to 28–30% in continuous forest. The major characteristic of Bakerella clavata enabling it to be an important fallback or staple resource, or both, is its extended phenology. The difference in resource utilization between sites may have important implications for nutritional status, as well as ranging and social behavior, largely owing to the small size and high abundance of feeding patches of Bakerella. Understanding resource shifts in fragments can shed light on socioecological questions by providing comparisons between continuous forest and fragment populations with differing diets and resource distributions. In addition, understanding dietary shifts in fragments can aid in species-specific conservation efforts, while contributing to a better understanding of the considerable interspecific variability of primates in responses to fragmentation.