Three ways of assessing metapopulation structure in the butterfly Plebejus argus

1. Three independent methods were used to investigate population structure in the butterfly Plebejus argus . First, migration and dispersal ability were measured by mark–release–recapture in seven adjacent habitat patches, and by release of butterflies in unoccupied habitat. Secondly, colonization of newly created habitat was observed over 7 years. Finally, genetic differentiation of local populations within a metapopulation was investigated. Sampled local populations included parts of the mark–release–recapture study area.
2. Plebejus argus is relatively sedentary: the maximum movement detected was 395 m, and only 2% of individuals moved further than 100 m between recaptures on different days. None the less, adjacent local populations in the mark–release–recapture study area were linked by occasional migration, with ≈ 1.4% of individuals moving between patches separated by 13–200 m.
3. Despite low mobility, observed colonizations occurred rapidly over distances of 1 km. Because P. argus occurs at high population densities, 1.4% migration can generate enough migrants to colonize newly suitable habitat quickly at this spatial scale.
4. Mark–release–recapture data were used to predict that there would be limited genetic differentiation through drift between local populations at this spatial scale. The prediction was supported by allele frequency data for the same local populations.
5. Genetic differentiation often indicates higher levels of migration than are revealed by the movements of marked individuals. This study shows that when experimental releases and extensive marking are undertaken in areas that are large relative to most movements, indirect measures of gene flow and direct measures of dispersal can concur.
6. Evidence from the three different approaches was complementary, indicating that P. argus occurs as metapopulations within the study area.     

Biological control of the larger grain borer Prostephanus truncatus (Coleoptera: Bostrichidae) in Kenya using a predatory beetle Teretrius nigrescens(Coleoptera: Histeridae)

The establishment of the predatory histerid beetle, Teretrius nigrescens Lewis, following its field release in south eastern Kenya in 1992, and its impact on populations of the larger grain borer, Prostephanus truncatus (Horn), in woodland habitats is evaluated. Pheromone trap catch data show a single strong peak of P. truncatus from November to January, coincident with the short rains. Comparisons of P. truncatus pheromone trap catches before and after predator establishment, and in areas with and without T. nigrescens, show a sustained decline of over 80% in P. truncatus abundance over a 5-year period, following the establishment T. nigrescens. Concurrent laboratory studies of the impact of T. nigrescens on populations of P. truncatus raised on a wood substrate showed a 77% reduction in the growth of the pest population. These results are compared with published findings of the impact of T. nigrescens as a biological control agent of P. truncatus in west Africa.     

Increased drag, and thus lower speed: a cost for morphological defence in Bosmina (Eubosmina) (Crustacea: Cladocera)

1. The swimming speed of two forms, an extreme and a typical, within the cladoceran subgenus Eubosmina were examined using a three-dimensional video-technique. The extreme form has a very high carapax and extremely long antennule, features probably involved in predator defence.
2. It was found that the extreme form swam almost 40% slower than the typical form.
3. Calculations show that the extreme form had to work at least 12% harder to swim at the same speed, or if it used the same amount of energy to swim, the extreme form would swim 6% slower. Increased drag, because of its distinguishing carapax and antennule, is thus the most likely explanation for the slower swimming speed of the extreme form, assuming it selects the same power output.
4. Swimming speed can be correlated to food intake either by the frequency of hits to edible food particles or by the time to swim from a poor food patch to a good one. So the reduced speed is probably a great cost for the extreme form.     

What changed the demography of an introduced population of an herbivorous lady beetle?

1. The population dynamics of an introduced population of Epilachna niponica (Lewis) (Coleoptera: Coccinellidae) was investigated for a 7-year period following its introduction to a site outside of its natural range. A population from Asiu Experimental Forest was introduced to Kyoto University Botanical Garden, 10 km south of its natural distribution.
2. Arthropod predation was much lower in the introduced than in the source population. As a result of the lower predation in the Botanical Garden, larvae reached densities five times higher than in the Asiu Forest and host plants were frequently defoliated. Food shortage caused larval deaths from starvation and increased dispersal.
3. The density of the introduced population was much more variable than that of the source population. The variation in population density in both the introduced and source populations is limited by density-dependent reduction in fecundity and female survival. However, variation in the introduced population's density was increased due to host plant defoliation that resulted in overcompensating density-dependent mortality. In years with high larval density plants were defoliated and this increased adult mortality during the prehibernation period. Besides, the density-dependent regulatory mechanisms that produce population stability were weaker in the introduced population than in the source population.     

Spatial and temporal variation in the parasitoid assemblage of an exophytic polyphagous caterpillar

Abstract 1. Over 3400 larvae of the polyphagous ground dwelling arctiid Grammia geneura were sampled and reared over seven generations in order to characterise its parasitoid assemblage and examine how and why this assemblage varies over time and space at a variety of scales.
2. The total parasitoid assemblage of 14 species was dominated both in diversity and frequency by relatively polyphagous tachinid flies.
3. Both the composition of the parasitoid assemblage and frequency of parasitism varied strikingly among and within sampling sites, seasons, and years.
4. Overall rates of parasitism increased consistently over the duration of caterpillar development.
5. Within sampling sites, parasitism rates were non-random with respect to habitat structure and caterpillar behaviour for the most abundant parasitoid species.
6. The large variability in parasitoid assemblage structure over space and time in this system may be a function of local host population abundance, habitat-specific parasitism, and indirect interactions between G. geneura and other Macrolepidoptera through shared oligophagous and polyphagous parasitoids.     

Salivary detection of periodontopathic bacteria in periodontally healthy children

BACKGROUND: Salivary occurrence of periodontopathic bacteria is of interest especially in children as a risk indicator for the transmission, development and control of periodontal disease. We assessed the prevalence of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Prevotella intermedia, Prevotella nigrescens and Treponema denticola as microbial complexes in the saliva of children with mixed dentition and healthy gingiva. MATERIALS AND METHODS: Paraffin-stimulated saliva samples were collected from 41 children (22 boys and 19 girls), aged 6-13 years old. Gingival health was determined during the initial screening exam. The test bacteria were identified using a 16S rRNA-based PCR analysis. RESULTS: P. nigrescens was the most frequent species (80%), followed by T. denticola (32%), A. actinomycetemcomitans (24%) and P. gingivalis (12%). P. intermedia and T. forsythia were not detected. P. nigrescens was also common species in combinations. Paired and triple bacterial combinations were found in 24% and 20% of all children, respectively. There was no positive association between bacterial combinations in colonization and subject's gender (P>0.05, Fisher exact test). CONCLUSION: The salivary presence of P. nigrescens, T. denticola, A. actinomycetemcomitans and P. gingivalis but not P. intermedia and T. forsythia can occur in childhood without clinical signs of gingival disease. Thus, the possible risk of bacterial transmissions through saliva and, the need to screen for periodontal pathogens should be considered before mixed dentition.     

Genetic differences among brown trout, Salmo trutta, stocks and their importance for the conservation and management of the species

SUMMARY. 1. Review of published studies on genetic variation, as shown by electrophoretic studies of protein variation, in natural brown trout ( Salmo trutta L.) populations from Britain and Ireland, Finland, France, Greece, Iceland, Norway, Sweden, U.S.A. and U.S.S.R., revealed abundant geographical variation in gene frequency with individual populations containing only a limited part of the gene diversity of the species.
2. Thirty-eight (54%) of the seventy gene loci examined have been found to be polymorphic in the species with an average population showing polymorphism at 16% of its loci (range 0-34.8%).
3. The brown trout is naturally subdivided into a large number of reproductively isolated and genetically distinct populations within, as well as among, drainages.
4. Two independent post-glacial colonizations, by genetically distinct races, followed by independent evolution in separate drainages over the past 13,000 years is seen as responsible for the genetic diversity of brown trout in north-western Europe.
5. Many genetically unique populations have been lost in the past 100 years and there is an urgent need to identify and conserve the remaining genetic diversity. Genetically unique populations are an irreplaceable resource for rational management in relation to angling and future aquaculture potential.     

Seroprevalence of chagas infection in the donor population

We retrospectively calculated the prevalence and epidemiologic characteristics of Chagas infection in the New York blood donor population over three years utilizing the New York Blood Center's database of the New York metropolitan area donor population. Seventy Trypanosoma cruzi positive donors were identified from among 876,614 donors over a 3-year period, giving an adjusted prevalence of 0.0083%, with 0.0080% in 2007, 0.0073% in 2008, and 0.0097% in 2009. When filtered only for self-described "Hispanic/Latino" donors, there were 52 Chagas positive donors in that 3-year period (among 105,122 self-described Hispanic donors) with an adjusted prevalence of 0.052%, with 0.055% in 2007, 0.047% in 2008, and 0.053% in 2009. In conclusion, we found a persistent population of patients with Chagas infection in the New York metropolitan area donor population. There was geographic localization of cases which aligned with Latin American immigration clusters.     

Defoliation tolerance affects the spatial and temporal distributions of larch sawfly and natural enemy populations

1. The monophagous larch sawfly, Pristiphora erichsonii, requires larch, Larix spp., shoots for oviposition and foliage for larval development. The hypothesis that chronic defoliation reduces shoot availability for adult females, causing shifts in host use within plantations of L. decidua and L. leptolepis , was evaluated over a 3-year period.
2. Larch productivity and sawfly abundance varied six- to 10-fold among individual trees within each plantation. Sawflies concentrated oviposition on the most rapidly growing trees, and had a marginal impact on shoot production. Consequently, sawfly herbivory on individual trees remained relatively constant for 3 years, failing to support the hypothesis that P. erichsonii defoliation causes shifts in host use.
3. Pristiphora erichsonii larval performance varied 20–30% among individual host trees. The oviposition event did not significantly affect larval performance or foliar nutrient content.
4. The relationship between cocoon survival and natural enemy abundance was evaluated among fifteen L. leptolepis trees. Parasites and predators killed over 65% of the 18 315 cocoons sampled. The proportion of cocoons killed by parasitoids declined significantly with P. erichsonii density, while predation rates increased under heavily infested trees. Overall, the proportion of cocoons killed by parasitoids and predators did not vary with sawfly density.
5. Results indicate that components of host vigour, herbivore performance and natural enemy guilds exhibit substantial spatial heterogeneity among trees within plantations of exotic Larix trees. Moreover, individual larch can tolerate repeated oviposition and herbivory without a rapid loss in shoot production. The potential for host plant physiological tolerance to herbivory to interact with natural enemy population dynamics and behaviour so as to stabilize herbivore population patterns is discussed.     

Reviews of publications

Book reviewed in this article:
New Plant Sources for Drugs and Food from the New York Botanical Garden Herbarium , by Siri von Reis and Frank J. Lipp, Jr.
Botany: Plant Biology and its Relation to Human Afairs , by Jean H. Langenheim & Kenneth V. Thimann.
How to Know Western Australian WildJEowers, Part IV , (2nd edition) by B. J. Grieve & W. E. Blackall.
Thonner's Analytical Key to the Families of Flowering Plants , by R. Geesink, A. J. M. Leeuwenberg, C. E. Ridsdale & J. F. Feldkamp.
Insects of an Amazon Forest , by N. D. Penny and J. R. Arias.
Ordering the World: A History of Classzfying Man , by David Knight.     

Colonising aliens: caterpillars (Lepidoptera) feeding on Piper aduncum and P. umbellatum in rainforests of Papua New Guinea

Abstract.  1. Caterpillar assemblages feeding on two alien plants, Piper aduncum and P. umbellatum , were studied in lowland rainforest in Papua New Guinea and compared with assemblages from 69 species of native woody hosts, including congeneric P. macropiper .
2. Species richness of caterpillars feeding on P. aduncum (29 species per 1500 m² of foliage) and P. umbellatum (36 species) was higher than the median richness for the 69 native hosts (23 species).
3. The probability that a caterpillar species colonised alien Piper increased with its host range from 3% for the species feeding on a single plant family to 92% for the species with host range >10 plant families.
4. The assemblage on P. aduncum was dominated by a single species ( Herpetogramma sp. near licarsisalis , Crambidae), which represented 48% of individuals, and also had a high proportion (34%) of rare species, collected as single individuals. This community structure was indistinguishable from that of a typical native host. In contrast, the P. umbellatum assemblage was unusual as no species represented >10% of individuals.
5. The aggressive invasion by P. aduncum of early successional vegetation is not explained by a competitive advantage due to low herbivore load, as the abundance of caterpillars feeding on it was comparable to that of native pioneer plants.
6. The caterpillar assemblage on P. aduncum demonstrated that an assemblage indistinguishable from native assemblages in density, species richness, and dominance structure (but not in host specificity) can originate from the existing species pool in lowland rainforests on a recently established tree species in <50 years.     

Fine-scale patterns of genetic variation indicate non-equilibrium gene frequency divergence in the stream lily, Helmholtzia glaberrima

1. Helmholtzia glaberrima (Philydraceae) is a rare plant, endemic to streams of the border ranges of Queensland and New South Wales, Australia.
2. We used AFLP markers to investigate genetic diversity and patterns of differentiation among 19 populations of H. glaberrima (24 for demographic analyses), and also collected data on the size, distribution and altitude of populations.
3. Based on the distribution of populations, altitude significantly influenced the spatial arrangement of H. glaberrima along stream systems, with population size and frequency greatest in upstream habitat.
4. Patterns of genetic diversity within populations were not related to population size or distribution. Altitude and genetic diversity were related, with upstream and downstream populations having higher genetic diversity than mid-stream populations. Differentiation among populations was pronounced at all spatial scales and did not conform to a hierarchical model of gene flow.
5. Both genetic diversity and differentiation data sets indicated that strong non-equilibrium conditions associated with persistent founder effects, and not landscape characteristics, have shaped patterns of genetic diversity and differentiation in H. glaberrima . Patterns of distribution indicate that populations are distributed over a discontinuous ecological gradient, which becomes marginal at lower altitudes.     

Effects of supplementary feeding on growth and reproduction of three carnivorous plant species in a subarctic environment

1 The effect of supplementary feeding on growth and reproduction of three carnivorous plants species was investigated over a 6‐year period. Pinguicula alpina , P. villosa and P. vulgaris populations growing at two altitudes in a subarctic environment were fed with fruit flies ( Drosophila melanogaster ).
2 Fed plants increased in size relative to control plants during the first years. Subsequently a stable size difference between feeding levels was established. The weight of the over‐wintering part was higher in fed plants than in control plants.
3 The flowering frequency (i.e. proportion of plants in a population carrying flowers) was also higher in the fed plants. The proportion of flowering plants increased in the feeding treatment compared to control plants during more‐or‐less the whole experimental feeding period (5–6 years). Seed production also increased slowly in response to feeding.
4 No feeding effect on nitrogen and phosphorus concentrations in seeds and over‐wintering parts was found.
5 In most characteristics the high‐altitude populations were less responsive than populations growing at low altitude. In the high‐altitude population reproduction failed repeatedly, suggesting that seed output may be more dependent on abiotic factors than on resource availability in cold environments.
6 Pinguicula villosa and P. vulgaris used the new resources the same summer for increased leaf rosette growth and current reproduction, showing these species to be income breeders, while the third species ( P. alpina ) allocated a larger proportion to storage and future reproduction, characteristic of a capital breeder.     

A re-evaluation of plants referred to as Pteridiutn herediae (Colmeiro) Love & Kjellqvist

SHEFFIELD, E., WOLF, P. G., HAUFLER, C. H., RANKER, T. A. & JERMY, A. C, 1989. Are-evaluation of plants referred to as Pteridiutn herediae (Colmeiro) Love & Kjellqvist. Based on perceived differences in morphology, chromosome number and habitat, specimens of Pteridiutn from southern Spain have been segregated by previous authors as a species distinct from Pteridium aquilinum , and called Pteridium herediae. However, type specimens of this taxon cannot be found. New collections of Pteridium from similar habitats in the area were examined and analysed in the present study and the results compared with those from British plants (P. aquilinum). The Spanish plants were not found to differ significantly from P. aquilinum morphologically, and all yielded chromosome counts (sporophytes, 104; gametophytes, 52) considered typical for the genus. Genotype frequency data obtained from isozyme electrophoresis of Spanish and British Pteridium yielded a genetic identity of 0.86; well within intraspecific distances found in other ferns.
These data indicate that there are currently no grounds for accepting that a form of Pteridium , distinguishable from P. aquilinum on the basis of differences in morphology, chromosome number, habitat or biochemistry, exists on the limestone soils of the Sierra de Cazorla region of southern Spain.     

The gene coding for nigrescin produced by Prevotella nigrescens ATCC 25261

Aim:  To identify the gene that encodes nigrescin, a bacteriocin produced by Prevotella nigrescens ATCC 25261.
Methods and Results:  Each open reading frame (ORF) of the nig gene cluster ( nigA, nigB, nigC and nigD ) was transferred into an expression vector. The recombinant proteins encoded by nigA, nigB, nigC and nigD were purified and assayed for bacteriocin activity against Porphyromonas gingivalis . The ORFs of the nig gene cluster in Pr. nigrescens ATCC 25261 were re-analysed. It revealed that the position of nig ORFs was similar to previously designated locations, except that the start codon of nigC was reassigned. The new nigC gene started at the nucleotide base position 2454 and stopped at position 3608 (the position designated is relative to the first nucleotide base of the nig locus) and putatively encoded a protein with a predicted molecular mass of 41·9 kDa. The N-terminal 6xHistidine-tag recombinant proteins of NigA, NigB, NigC and NigD were overexpressed in Escherichia coli BL21 star (DE3) and were purified using Ni-NTA resins. Only recombinant NigC showed inhibitory activity against P. gingivalis A244 with minimal inhibition concentration (MIC) of 40 μg ml⁻¹.
Conclusion:  These results indicate that nigC is the gene that encodes nigrescin.
Significance and Impact of the study:  This is the first report that indicates that the gene nigC codes for nigrescin, a bacteriocin produced by Pr. nigrescens ATCC 25261.     

The distribution of wood-ants (Formica lugubris Zetterstedt) in a northern English forest

Abstract. 1. A survey of 202 ha of planted forest in Langdale Forest, North Yorkshire, in 1972 discovered 326 occupied and thirty-eight deserted nests of Formica lugubris Zetterstedt. The average density of occupied nests was therefore 1.61 ha^-1.
2. Nests were associated with most crop trees and wild trees present, but were most abundant near to plantation margins and regenerating natural scrub.
3. In planted areas 76% of nests were found 5 m or less from the plantation boundary. More nests were found on the south and west border of plantations than on the north and east respectively, and most nests were not shaded from the south or southeast.
4. An analysis of nearest neighbour measurements showed that the dispersion of nests was not random but contagious (clumped). Nest mounds were higher in shaded situations than in unshaded.
5. The diameter of nest mounds was greater in areas planted with trees before 1945 than in areas planted since 1945.
6. The present population of F.lugubris appears to have spread into planted areas from nests present in marginal natural woodland which escaped the disturbance of the area at the time of planting.     

Studies on predation of Prostephanus truncatus (Horn) (Col., Bostrichidae) and Sitophilus zeamais Mots. (Col., Curculionidae) at different densities on maize by Teretriosoma nigrescens Lewis (Col., Histeridae)

Laboratory experiments using whole cobs were conducted to examine the effect of varying densities of the larger grain borer, Prostephanus truncatus and the maize weevil, Sitophilus zeamais on rate of population increase by the histerid beetle, Teretriosoma nigrescens , a predator primarily of P. truncatus . Densities of all species of insects were determined at the end of the experiment, and an electrophoretic analysis of gut content was conducted on larval and adult T. nigrescens sampled during the experiments. Results indicated that T. nigrescens has a strong preference for P. truncatus and densities of T. nigrescens were associated only with densities of P. truncatus . The maize weevil played little role as an alternative prey or in interfering with T. nigrescens reproduction.     

Effects of patch size and density on flower visitation and seed set of wild plants: a pan-European approach

1.  Habitat fragmentation can affect pollinator and plant population structure in terms of species composition, abundance, area covered and density of flowering plants. This, in turn, may affect pollinator visitation frequency, pollen deposition, seed set and plant fitness.
2.  A reduction in the quantity of flower visits can be coupled with a reduction in the quality of pollination service and hence the plants' overall reproductive success and long-term survival. Understanding the relationship between plant population size and/or isolation and pollination limitation is of fundamental importance for plant conservation.
3.  We examined flower visitation and seed set of 10 different plant species from five European countries to investigate the general effects of plant populations size and density, both within (patch level) and between populations (population level), on seed set and pollination limitation.
4.  We found evidence that the effects of area and density of flowering plant assemblages were generally more pronounced at the patch level than at the population level. We also found that patch and population level together influenced flower visitation and seed set, and the latter increased with increasing patch area and density, but this effect was only apparent in small populations.
5.   Synthesis. By using an extensive pan-European data set on flower visitation and seed set we have identified a general pattern in the interplay between the attractiveness of flowering plant patches for pollinators and density dependence of flower visitation, and also a strong plant species-specific response to habitat fragmentation effects. This can guide efforts to conserve plant–pollinator interactions, ecosystem functioning and plant fitness in fragmented habitats.     

A method for validating stochastic models of population viability: a case study of the mountain pygmy-possum (Burramys parvus)

1.  A method of validating stochastic models of population viability is proposed, based on assessing the mean and variance of the predicted population size.
2.  The method is illustrated with a model of the population dynamics of the mountain pygmy-possum ( Burramys parvus Broom 1895), based on annual census data collected from a single population in the Snowy Mountains of New South Wales, Australia between 1986 and 1997. The model incorporates density-dependence in survivorship and recruitment, and demographic and environmental stochasticity.
3.  The model appeared to make reasonable predictions for the three populations that were used for validation, provided the equilibrium population size was estimated accurately. This may require that differences in habitat quality between populations be taken into account.
4.  Following validation, the model was given new parameters using the additional data from the three populations, and the risk of population decline within the next 100 years was assessed. Although populations as small as 15 females are predicted to be relatively safe from extinction caused by stochastic processes, B. parvus appears vulnerable to loss of habitat and reductions in the population growth rate.
5.  The approach used in this paper is one of few attempts to validate a model of population viability using field data, and demonstrates that some aspects of stochastic population models can be tested.     

Hemolytic and hemagglutinating activities of Prevotella intermedia and Prevotella nigrescens

A total of 91 isolates of Prevotella intermedia or Prevotella nigrescens from subgingival sites were identified by PCR using primers specific for sequences of 16S rRNA. The hemolytic and hemagglutinating activities of the P. intermedia isolates exhibited significantly higher levels compared to those of the P. nigrescens isolates by quantitative analysis. The hemagglutinin gene (phg) was found in 23 of 26 P. intermedia isolates (88.5%), whereas it was found in only two of 44 isolates (4.5%) of P. nigrescens. The high hemolytic and hemagglutinating activities of P. intermedia may be involved in the pathogenicity of P. intermedia in the progression of periodontal disease.