Carbon flow dynamics in the pelagic community of the Sau Reservoir (Catalonia,NE Spain)

Changes in the pelagic community structure and activity along the longitudinal axis of the eutrophic Sau Reservoir (Catalonia, NE Spain) were studied between 1996 and 1999. Samples were taken from several transects from river to dam, measuring dissolved organic carbon (DOC), bacterial abundance and production, chlorophyll a concentration, heterotrophic nanoflagelate (HNF) and ciliate abundances and their grazing rates, and zooplankton density. The role of microbial and classical food chains (i.e., based directly on phytoplankon) were compared in the Sau Reservoir by analysing river-to-dam gradients in biomass and carbon and their temporal changes. The detritic metabolic pathway was more important near to the inflow, due to high allochthonous organic matter loads allowing the rapid development of the microbial food web. Protozoans (HNF and ciliates) consumed most of the bacterial production (i.e., >50%) in the reservoir. As opposed to the systems of lower trophic status ciliate carbon biomass and bacterivory contributions were larger than those of the HNF. We estimated species-specific ciliate growing rates on bacteria and distinguished several periods with high importance of distinct ciliate communities.     

Pelagic Ciliates in a Large Mesotrophic Lake: Seasonal Succession and Taxon‐Specific Bacterivory in Lake Constance

The taxonomic composition of the ciliate assemblage and their taxon‐specific bacterial grazing rates in Lake Constance were investigated over the course of one year. Bacterial grazing rates were measured using natural fluorescently labelled bacteria (FLB) and compared to bacterial production. Small species such as Balanion planctonicum/Urotricha furcata and Rimostrombidium spp./Halteria sp. were the most numerous ciliates on the annual average. Larger ciliates such as Rimostrombidium lacustris and Limnostrombidium spp. contributed significantly to total ciliate biomass, but were relatively unimportant as bacterial grazers. Per capita ingestion rates ranged from 0–194 bacteria ciliate⁻¹ h⁻¹ and changed seasonally up to a hundredfold within a given taxon. Approximately 1% of the bacterial production were removed by the ciliate community on the annual average. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The fly factor phenomenon is mediated by interkingdom signaling between bacterial symbionts and their blow fly hosts

We tested the recent hypothesis that the"fly factor"phenomenon(food cur-rently or previously fed on by flies attracts more flies than the same type of food kept inccessible to flies)is mediated by bacterial symbionts deposited with feees or regur-gitated by feeding flies.We allowed laboratory-reared black blow flies,Phormia regina(Meigen),to feed and de fecate on bacterial Luria-Bertani medium solidified with agar,and isolated seven morphologically distinct bacterial colonies.We identified these us-ing matrix-assisted laser desorption/ionization mass spectrometry and sequencing of the 165 rRNA gene.In two-choice laboratory experiments,traps baited with cultures of Pro-teus mirabilis Hauser,Morganella morganii subsp.sibonii Jensen,or Serratia marcescens Bizio,captured significantly more flies than corresponding control jars baited with tryptic soy agar only.A mixture of seven bacterial strains as a trap bait was more attractive to flies than a single bacterial isolate(M.m.siboni).In a field experiment,traps baited with agar cultures of P:mirabilis and M.m siboni in combination captured significantly more flies than lraps baited with either bacterial isolate alone or the agar control.As evident by gas chromatography-mass spectrometry,the odor profiles of bacterial isolates differ,which may explain the additive effect of bacteria to the attractiveness of bacterial trap baits.As"generalist bacteria,"P mirabilis and M.m.sibonii growing on animal protein(beef liver)or plant protein(tofu)are similarly effective in attracting flies.Bacteria-derived airborne semiochemicals appear to mediate foraging by flies and to inform their feeding and oviposition decisions.     

Participation of a Specific Substrate Degrading Strain in a Mixed Bacteria Culture as a Result of Ciliate Grazing

Participation of nitrilotriacetic acid degrading bacterial strain NTA-1 in the continuous-cultivated mixed culture was studied under different conditions including predation pressure of the ciliate Dexiostoma campyla (STOKES , 1886). From the viewpoint of dispersed/flocculated biomass distribution, significant relationships between NTA-1 and total bacteria ratio, and dispersed and total biomass ratio were proved in the systems without high concentrations of ciliates. The ciliate concentrations reaching 10⁴ ml⁻¹ stabilized flocculated biomass growth without directly affecting NTA-1 portion. Using fluorescently labelled NTA-1 bacteria, filter feeding rates of ciliates were evaluated (maximum individual uptake rate upon NTA-1 bacteria as a number of bacteria per ciliate per hour being 120 h⁻¹ and 260 h⁻¹ under ciliate division rate of 0.3 day⁻¹ and 1 day⁻¹, respectively). Biomass balance showed that dispersed NTA-1 bacteria should not serve as the sole feeding source for these free-swimming ciliates. The role of diversity of mixed bacterial diet in ciliate growth and the role of ciliate predation in stabilizing bacterial assemblage structure was proved.     

Conspicuous Peak of Oligotrichous Ciliates Following Winter Stratification in a Bog Lake

We analysed early spring protozooplankton peaks following winterstratification in two different basins (northeast, NE; southwest,SW) of an artificially-divided bog lake Große Fuchskuhle(Brandenburg,Germany). The maximum ciliate biomass and numbers (660 and 990µg l^–1 of organic carbon, and 290 and 260 cellsml^–1 in NE and SW, respectively) were reached in the surfacelayer during the ice melting and then continuously decreased.The surface layers were numerically dominated by species ofthe genus Urotricha, while in the ciliate biomass during thefirst part of the study, a mixotrophic oligotrich, Pelagostrombidiummirabile prevailed (C_org up to 940 µg l^–1). We observeda conspicuous ciliate peak that could not be related to thefeeding activity of the dominant ciliate species upon picoplankton.Seemingly, the peak was related to the specific conditions resultingfrom the ice melting where these ciliates could be concentrated.Additionally, the mixotrophy of oligo-trichous species allowedthem to penetrate below the oxycline, although feeding on nanoplanktonsuch as flagellates was also very likely. Our direct measurementsof uptake rates of bacteria showed that the abundant strombidiidswere not nutritionally dependent on bacterivory. However, theciliate uptake rate (up to 670 bacteria ciliate^–1 h^–1)contributed significantly to the overall bacteria mortalityrate. The maximum (community average) cell-specific ciliatefeeding rate of over 200 bacteria ciliates^–1 h^–1was reached, along with an increasing contribution of scuticociliates,paralleled by a drop in large oligotrichs.     

Occurrence of bacterivory in Cryptomonas,a common freshwater phytoplankter

Summary Bacterivory was detected by incorporation of 0.57 m diameter, fluorescent polystyrene beads and fluorescently labeled bacteria (FLB) in two cultured species of Cryptomonas (C. ovata and C. erosa), and a population of Cryptomonas sp in a humic, mesotrophic lake. Rates of ingestion and clearance were very low, and similar for the cultures and the in situ population. The in situ population incorporated 0.7–1.7 bacteria cell^-1 h^-1, thereby ingesting 0.3%–2.0% of the total bacterial numbers present in the water per day, and receiving less than 2% of its carbon content per day through bacterivory. Thus, bacterivory by Cryptomonas was quantitatively important neither as a sink for bacterial biomass, nor as a carbon source for the algal cells. Possibly, it served in the uptake of essential nutrients.     

Species characterization and responses of subcortical insects to trap‐logs and ethanol in a hardwood biomass plantation

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Trapping of European buprestid beetles in oak forests using visual and olfactory cues

Trapping approaches developed for the emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), were adapted for trapping several European oak buprestid species. These approaches included the use of natural leaf surfaces as well as green and purple plastic in sticky trap designs. Plastic surfaces were incorporated into novel ‘branch‐trap’ designs that each presented two 5 × 9‐cm² rectangular surfaces on a cardboard structure wrapped around the leaves of a branch. We used visual adult Agrilus decoys in an attempt to evoke male mating approaches toward the traps. Our first experiment compared the attractiveness of visual characteristics of the surfaces of branch‐traps. The second looked at the effect on trap captures of adding semiochemical lures, including manuka oil, (Z)‐3‐hexen‐1‐ol, and (Z)‐9‐tricosene. In total, 1 962 buprestid specimens including 14 species from the genus Agrilus were caught on 178 traps in a 22‐day time‐span. Overall, the green plastic‐covered branch‐traps significantly out‐performed the other trap designs. We further found that the presence of an EAB visual decoy placed on the trap surface often increased captures on these green traps, but this effect was stronger for certain Agrilus species than for others. The visual decoy was particularly important for the most serious pest detected, Agrilus biguttatus Fabricius, which was captured 13 times on traps with decoys, but only once without a decoy. There were some small but significant effects of odor treatment on the capture of buprestids of two common species, Agrilus angustulus Illiger and Agrilus sulcicollis Lacordaire. There were also 141 Elateridae specimens on these traps, which were not influenced by trap type or decoys. The results suggest that small branch‐traps of this nature can provide a useful new tool for monitoring of buprestids, which have the potential to be further optimized with respect to visual and olfactory cues.     

The importance of olfactory and visual cues in developing better monitoring tools for Sirex noctilio (Hymenoptera: Siricidae)

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Microbial community development in the traps of aquatic Utricularia species

We examined trap fluid of three aquatic carnivorous species of Utricularia (Lentibulariaceae) to assess the role of microbial community within their traps in plant nutrient acquisition. In the context of increasing trap age, we characterized microbial community composition using phospholipid fatty acid (PLFA) analysis and microscopy. Nutrient content in various fractions of the trap fluid was analyzed and the abundance of free-suspended bacteria estimated. The activities of extracellular phosphatase in the trap fluid were determined using fluorometry and the contribution of the microbial community to phosphatase production assessed by epifluorescence microscopy. The trap microbial community seems to be largely derived from Utricularia associated periphyton. PLFA analysis revealed that trap fluid contained all components of a complex microbial food web with bacteria forming more than 58% of the viable microbial biomass in the trap. Trap age seems to be the key factor in determining the patterns of microbial community development as well as enzyme production. The amount of nutrients increases with increasing trap age, and the total amounts of C, N, and P accumulated within traps during their lifetime are relatively large—of the order of 100 mg L⁻¹ for C and N, and between 0.2 and 0.6 mg L⁻¹ for P. A significant part of the nutrient pool is present in the dissolved form. Trap fluid stoichiometry (molar N:P ratios about 100) as well as the presence of nutrient limited microbial cells (molar N:P ratios 25–61) indicates the importance of phosphorus rather than nitrogen for the nutrition of Utricularia. Our findings support the hypothesis that mutualism, apart from the predator–prey interaction, is an important association in aquatic Utricularia traps and that the trap-associated microbial community may be of benefit to the rootless aquatic Utricularia species facing problems with P acquisition due to the loss of roots in their evolution.     

Bacterioplankton production and protozoan bacterivory in a mesotrophic reservoir

Protozoan bacterivory [via uptake of fluorescently labelledbacteria (FLB)] and production of bacteria ([³H]thymidine assay)were simultaneously measured in the mesotrophic ímovReservoir (Southern Bohemia) from April to November, 1988. Heterotrophicnanoflagellates (HNF) were mostly responsible for a greaterfraction of protozoan bacterivory during the spring period.From 10 to 23% of bacterial production was grazed daily withthe only exception of the spring peak of ciliate abundance (upto 60%). Protozoans decreased significantly during the clearwaterphase (ciliates disappeared), and thus their role in bacterivorywas negligible. Through the summer-fall period ciliates, notHNF, were the most important bacterial micrograzers. Protozoancommunity grazing balanced or even exceeded the daily bacterialproduction in August and September. Alternate fates of bacterialproduction besides protozoan grazing during the spring periodare discussed.     

Protistan bacterivory in an oligomesotrophic lake: Importance of attached ciliates and flagellates

Seasonal and depth variations of the abundance, biomass, and bacterivory of protozoa (heterotrophic and mixotrophic flagellates and ciliates) were determined during thermal stratification in an oligomesotrophic lake (Lake Pavin, France). Maximal densities of heterotrophic flagellates (1.9 × 10³ cells ml^–1) and ciliates (6.1 cells ml^–1) were found in the metalimnion. Pigmented flagellates dominated the flagellate biomass in the euphotic zone. Community composition of ciliated protists varied greatly with depth, and both the abundance and biomass of ciliates was dominated by oligotrichs. Heterotrophic flagellates dominated grazing, accounting for 84% of total protistan bacterivory. Maximal grazing impact of heterotrophic flagellates was 18.9 × 10⁶ bacteria 1^–1h^–1. On average, 62% of nonpigmented flagellates were found to ingest particles. Ciliates and mixotrophic flagellates averaged 13% and 3% of protistan bacterivory, respectively. Attached protozoa (ciliates and flagellates) were found to colonize the diatom Asterionella formosa. Attached bacterivores had higher ingestion rates than free bacterivorous protozoa and may account for 66% of total protozoa bacterivory. Our results indicated that even in low numbers, epibiotic protozoa may have a major grazing impact on free bacteria. Correspondence: C. Amblard.     

Influence of trap type, trap colour, and trapping location on the capture of the pine moth, Thaumetopoea pityocampa

Studies were conducted to evaluate the effect of type, location, and colour of traps baited with 1 mg of the sex pheromone (Z)‐13‐hexadecen‐11‐ynyl acetate in polyethylene vials on the capture of the pine processionary moth, Thaumetopoea pityocampa (Denis & Schiffermüller) (Lepidoptera: Thaumetopoeidae), males. The experiments were carried out during two flight seasons in 2002 and 2003 at a low elevation Mediterranean pine forest on the hill of Goritsa (Magnesia, Thessaly, Central Greece). The hill is covered by approximately 120 ha of pines, among which Pinus brutia Ten. (Pinaceae) is predominant with Pinus halepensis Mill. (Pinaceae) as second most common species. Among the commercially available trap types used, the Delta and Pherocon II captured significantly more males than the Funnel trap. Furthermore, pine density had a significant effect on trap type and trap colour catches. Delta traps caught significantly more adults than the other two trap types in the low density pine stand, while in the medium and high‐density pine stands no significant differences were noted between Delta and Pherocon II traps. In addition, trap colour performance varied according to pine density; white‐ and yellow‐coloured traps caught significantly more males than the other two trap colours in the high‐density stand. The first adults were captured in traps during May, and traps continued to capture adults in low numbers (< two individuals per trap) until mid‐June. A period of 3–4 weeks of no trap captures followed until mid‐July, when captures restarted, at low numbers. The peak of T. pityocampa flight was observed during late August–September.     

Ciliate community structure, diversity and trophic role in offshore sediments from the Yellow Sea

We investigated the community structure, diversity and trophic role of ciliates in the sediments from 48 stations in the Yellow Sea using Ludox density centrifugation and quantitative protargol stain. The ciliate abundance ranged from 1 to 221cellscm(-3) and biomass from 0.0001 to 0.47μgCcm(-3) in the upper 8cm of the sediments. On average, 77% of ciliate abundance and 81% of biomass were distributed in the 0-2cm sediment layers, while the respective proportions were only about 6% and 3% in the 5-8-cm layers. Among the 198 morphospecies, Prostomatea was the most dominant group accounting for 45% of the total abundance and 58% of the total biomass. Carnivorous ciliates constituted the primary feeding type, occupying about 64% of the total biomass, followed by bacterivores (21%), algivores (12%) and omnivores (3%). The ciliate abundance and biomass in the upper 5cm of sediments were two orders of magnitude higher than those in the upper 10m of the Yellow Sea water column. The estimated ciliate bacterivory and herbivory indicate that ciliate ingestion had little direct influence on bacterial standing stock but possibly had an important impact on diatoms in the sediments from the Yellow Sea.     

Growth of Chlorella vulgaris and associated bacteria in photobioreactors

The aim of this study was to test three flat plate photobioreactor configurations for growth of Chlorella vulgaris under non‐axenic conditions and to characterize and quantify associated bacterial communities. The photobioreactor cultivations were conducted using tap water‐based media to introduce background bacterial population. Growth of algae was monitored over time with three independent methods. Additionally, the quantity and quality of eukaryotes and bacteria were analysed using culture‐independent molecular tools based on denaturing gradient gel electrophoresis (PCR‐DGGE) and quantitative polymerase chain reaction (QPCR). Static mixers used in the flat plate photobioreactors did not generally enhance the growth at the low light intensities used. The maximum biomass concentration and maximum specific growth rate were 1.0 g l^?1 and 2.0 day^?1 respectively. Bacterial growth as determined by QPCR was associated with the growth of C. vulgaris. Based on PCR‐DGGE, bacteria in the cultures mainly originated from the tap water. Bacterial community profiles were diverse but reproducible in all flat plate cultures. Most prominent bacteria in the C. vulgaris cultures belonged to the class Alphaproteobacteria and especially to the genus Sphingomonas. Analysis of the diversity of non‐photosynthetic microorganisms in algal mass cultures can provide useful information on the public health aspects and unravel community interactions.     

Efficacy of the pheromone (3Z)‐lactone and the host kairomone (3Z)‐hexenol at detecting early infestation of the emerald ash borer,Agrilus planipennis

The invasive emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is a major pest of ash trees, Fraxinus spp., in its introduced range in North America. Field studies were conducted to quantify the efficacy of traps baited with kairomone and pheromone lures for early detection of A. planipennis infestation. A trapping experiment demonstrated that green traps baited with the kairomone (3Z)‐hexenol detected at least one adult A. planipennis in 55.3% of plots with ‘nil to low’‐density infestations and in 100% of plots with ‘moderate to high’‐density A. planipennis infestations. Mean trap captures increased significantly with increasing infestation density. In terms of the optimal number of traps per plot, when one (3Z)‐hexenol‐baited trap was placed per plot, the trap detected populations in 62% of the plots with ‘low to moderate’‐density infestations through branch sampling. Detectability was increased to 82% when two traps were placed per plot. Finally, addition of female‐produced (3Z)‐lactone pheromone to traps significantly increased detection rates at both the trap and plot level, as compared with traps baited with the host volatile, (3Z)‐hexenol, alone (88 vs. 60%, respectively). Our results are the first to demonstrate the efficacy of baited green sticky traps for detecting low‐density A. planipennis infestations, particularly when the (3Z)‐lactone pheromone is used. This combination is therefore recommended for development of early‐detection protocols against A. planipennis.     

Performance of light‐emitting diode traps for collecting sand flies in entomological surveys in Argentina

The performance of two light‐emitting diode traps with white and black light for capturing phlebotomine sand flies, developed by the Argentinean Leishmaniasis Research Network (REDILA‐WL and REDILA‐BL traps), were compared with the traditional CDC incandescent light trap. Entomological data were obtained from six sand fly surveys conducted in Argentina in different environments. Data analyses were conducted for the presence and the abundance of Lutzomyia longipalpis, Migonemyia migonei, and Nyssomyia whitmani (106 sites). No differences were found in presence/absence among the three types of traps for all sand fly species (p>0.05). The collection mean of Lu. longipalpis from the REDILA‐BL didn´t differ from the CDC trap means, nor were differences seen between the REDILA‐WL and the CDC trap collection means (p>0.05), but collections were larger from the REDILA‐BL trap compared to the REDILA‐WL trap (p<0.05). For Mg. migonei and Ny. whitmani, no differences were found among the three types of traps in the number of individuals captured (p>0.05). These results suggest that both REDILA traps could be used as an alternative capture tool to the original CDC trap for surveillance of these species, and that the REDILA‐BL will also allow a comparable estimation of the abundance of these flies to the CDC light trap captures. In addition, the REDILA‐BL has better performance than the REDILA‐WL, at least for Lu. longipalpis.     

A carbon dioxide, heat and chemical lure trap for the bedbug, Cimex lectularius

Abstract A trap for the collection of bedbugs, Cimex lectularius Linnaeus (Hemiptera: Cimicidae), is described. The trap was baited with CO₂ (50–400 mL/min), heat (37.2–42.2 °C) and a chemical lure comprised of 33.0 μg proprionic acid, 0.33 μg butyric acid, 0.33 μg valeric acid, 100 μg octenol and 100 μg L‐lactic acid, impregnated into a gel. Laboratory studies, conducted in a square arena measuring 183 cm on each side, showed that traps with and without baits captured adult bedbugs, but traps with CO₂ emissions of 50–400 mL/min caught significantly (P < 0.05) more bedbugs than traps without CO_2. In an infested unoccupied apartment, traps with heat and with or without the chemical lure were tested without CO₂ on 29 trap‐days and with CO₂ on 9 trap‐days. The numbers of bedbugs captured were 656 and 5898 in traps without and with CO₂, respectively. The numbers of bedbugs of all development stages captured were significantly greater in traps with CO₂ (χ² = 15 942, d.f. = 1, P < 10^?9). A non‐parametric two‐way analysis of variance evaluation of six different traps with or without CO₂, heat or a chemical lure monitored over 19 trap‐days in an infested apartment showed that trap type was highly significant (n = 2833 bedbugs collected) (P < 10^?7). The trap with CO₂, heat and a chemical lure captured more bedbugs than the other traps, but only caught significantly more fourth and fifth instar nymphs than all other traps. Otherwise, the catches in this trap did not differ significantly from those caught by traps that contained CO₂ and heat only. The total numbers of bedbugs collected for each trapping date (pooling all six traps) followed an exponential decline over the trapping period. This type of trap, which caught bedbugs in unoccupied apartments with and without furniture, and in an occupied apartment, may have utility in studying the ecology of bedbugs, in detecting bedbug infestations and in reducing numbers of bites by trapping host‐seeking bedbugs.     

Optimising sampling methods for small mammal communities in Neotropical rainforests

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Fermentation products of the anaerobic ciliate Trimyema compressum in monoxenic cultures

A new monoxenic culture of the anaerobic ciliate Trimyema compressum was established on the purple nonsulfur bacterium Rubrivivax gelatinosus. Compared with the first monoxenic culture of T. compressum on a Bacteroides species no significant difference in growth rate was observed. Using both monoxenic cultures the fermentation products of the ciliate, acetate, lactate, formate and succinate were quantified. Ammonium was another product of the ciliates metabolism. The amount of the endproducts was dependent on the amount of bacteria consumed. The ratio of carbon consumed to ammonium formed was 8.7:1 indicating incomplete degradation of nitrogenous compounds of the bacterial biomass. Under microoxic conditions no effect of oxygen on the yield of the ciliate was observed but the amount of acetate and lactate was 25% lower. Cells of T. compressum with Methanobacterium formicicum as deliberately introduced endosymbiont did not form significantly different fermentation products, however, instead of formate methane was detected as product. The yield of the ciliate was not affected. It is concluded that methanogenic bacteria deliberately introduced into the cytoplasm of T. compressum as endosymbionts are pure commensalists.