Colony Presence Research Articles

Vision Technique for Vibrio Detection using Shrimp Cultivation Isolated Water in TCBS Agar Plates

Maintaining water quality is a crucial factor for shrimp cultivation. Detecting the vibrio bacteria distribution in the ponds could prove to be a crucial for successful cultivation. Thiosulfate-citrate-bile salts-sucrose (TCBS) agar is a commonly used medium to stimulate the Vibrio colony presence. In this research, water samples from shrimp cultivation were collected, isolated in TCBS agar plates, and incubated for 24 hours, afterwards exported as an image dataset. The YOLOv7 computer vision technique was implemented to detect and count Vibrio colonies with faster and higher precision compared to the tedious manual counting technique done by laboratory researchers. Additionally, this technique is applicable and scalable to large sets of data. From the execution done so far, the proposed system has achieved an average accuracy of 78.99%.

Modular deep learning enables automated identification of monoclonal cell lines

Monoclonalization refers to the isolation and expansion of a single cell derived from a cultured population. This is a valuable step in cell culture that serves to minimize a cell line’s technical variability downstream of cell-altering events, such as reprogramming or gene editing, as well as for processes such as monoclonal antibody development. However, traditional methods for verifying clonality do not scale well, posing a critical obstacle to studies involving large cohorts. Without automated, standardized methods for assessing clonality post hoc, methods involving monoclonalization cannot be reliably upscaled without exacerbating the technical variability of cell lines. Here, we report the design of a deep learning workflow that automatically detects colony presence and identifies clonality from cellular imaging. The workflow, termed Monoqlo, integrates multiple convolutional neural networks and, critically, leverages the chronological directionality of the cell-culturing process. Our algorithm design provides a fully scalable, highly interpretable framework that is capable of analysing industrial data volumes in under an hour using commodity hardware. We focus here on monoclonalization of human induced pluripotent stem cells, but our method is generalizable. Monoqlo standardizes the monoclonalization process, enabling colony selection protocols to be infinitely upscaled while minimizing technical variability.

Physicochemical and sensory characteristic of treated sugarcane juice

Sugarcane juice contains high sugar content which can deteriorate rapidly after the juice extraction process. In large juice industry, the deterioration of sugarcane juice can be reduced by pasteurisation and sterilisation treatment process. However, preservation techniques impart undesirable effect on sugarcane juice in terms of taste, colour, appearance and acceptability of the consumer. Therefore, in this study, the effect of pasteurisation process and addition of Spirulina platensis (S. platensis) water extract (0.2% vol/vol) were investigated for its physicochemical (pH, total soluble solid, colour and turbidity), microbiological evaluation (total plate count) and sensory characteristic of sugarcane juice. The addition of S. platensis water extract in sugarcane juice lower the pH value of tested sample contributing to the increase in the stability of sugarcane juice. The other physicochemical tests (total soluble solid, colour and turbidity) have definite correlation with the changes of pH value but not-significant (p > 0.05) in term of addition of S. platensis water extract into sugarcane juice samples. The microbiological evaluation revealed that high number of colony presence in sugarcane juice after storage for about two weeks and their number were reduced until end of testing period which may result from the depletion of nutrient and inhibition of by-product of reactions that happen in sugarcane juice sample. In terms of sensory testing, the addition of S. platensis water extract in sugarcane juice scored best as compared to control sample even though it does not give significant value (p > 0.05) compared to control sample. In conclusion, the addition of S. platensis water extract for treated sugarcane juice is significant as it improves consumer acceptability. The water extract could also acts as colouring agent in sugarcane juice without affecting the physicochemical and sensory properties of sugarcane juice.

672 An Investigation of Antibiotic Loading and Release in Acid-precipitated Keratin Proteins to Treat Topical Burn Infections

Abstract Introduction Human-hair derived keratin (KOS) protein has been selected in this investigation for its ability to bind antibiotic compounds and provide sustained release while withstanding harsh proteolytic environments such as inflamed, damaged tissue. The need to control local flora has been recognized as an imperative for wound healing, as recovery is significantly hampered by infection. This study investigates the synthesis of KOS-based particulate matter, developed using acid-precipitation, to load and release the water-soluble antibiotic ciprofloxacin (CIP). We hypothesize that ionically bound CIP release is tied to the degradation of KOS, therefore, bacterial metabolism, which produces proteolytic enzymes, will trigger CIP release thereby creating a novel self-extinguishing delivery system for contaminated skin wounds. Methods Ciprofloxacin hydrochloride was solubilized in deionized water (pH 5.3) under constant stirring. Freeze-dried KOS powder was added for an ultimately 5% w/v and 0.8% w/v solution of KOS and CIP, respectively. To improve the stability of KOS a water-soluble diglycidyl ether crosslinker was added to solutions and stirred for 24 hours. CIP-loaded protein was precipitated out by a hydrochloric acid induced pH reduction. Samples were collected and frozen at -20 °C prior to lyophilization, thus forming the stable product. Degradation of KOS and commensurate release of CIP were measured using a bicinchoninic acid (BCA) assay and fluorescent measurements of hydrated material supernatant. The reduction of bacterial colonies was validated by a broth inhibition assay whereby CIP-loaded KOS or unloaded KOS controls where hydrated in bacterial-laden broth cultures of Pseudomonas aeruginosa or Methicillin-resistant Staphylococcus aureus. Cultures were sampled at 24, 48, or 72 hours and plated to quantify colony-forming units. Results The presence of CIP in the KOS protein was confirmed and release rates follow similar patterns to that of KOS degradation. CIP-loaded proteins significantly reduce bacterial colony presence in concentrated inoculant solutions up to 72 hours. Conclusions CIP release does appear to coincide with KOS degradation, which is bolstered in the presence of infectious levels of bacteria. Ongoing studies aim to observe more robust models of infection and more controlled antibiotic release.

The role of wind fetch in structuring Antarctic seabird breeding occupancy

Avian breeding sites located along shorelines may allow easy access to aquatic food sources, but risk exposing birds and nests to high wind and wave action. One measure of exposure is wind fetch, the distance of open water over which wind can blow uninterrupted. By calculating fetch weighted by prevailing wind direction for breeding colonies of pursuit‐diving seabirds in the Antarctic Peninsula, we show that different members of this guild have opposing relationships to coastline exposure. Gentoo Penguins Pygoscelis papua preferentially occupied more enclosed sites with lower fetch. Surprisingly, however, Chinstrap Penguins Pygoscelis antarcticus and Antarctic Shags Leucocarbo bransfieldensis appear to prefer more exposed sites. Although considerable research has been devoted to understanding Antarctic seabird habitat suitability, the role of wind and wave exposure has not been considered in depth, in part because comprehensive data on colony presence and absence have only recently been made available. We propose several mechanisms for why fetch may act to differentiate niches among this guild. These findings may increase our ability to identify suitable breeding areas for these and other near‐shore breeding species as they respond to climate change.

The Clean pilot study: evaluation of an environmental hygiene intervention bundle in three Tanzanian hospitals

BackgroundHealthcare associated infections (HAI) are estimated to affect up to 15% of hospital inpatients in low-income countries (LICs). A critical but often neglected aspect of HAI prevention is basic environmental hygiene, particularly surface cleaning and linen management. TEACH CLEAN is an educational intervention aimed at improving environmental hygiene. We evaluated the effectiveness of this intervention in a pilot study in three high-volume maternity and newborn units in Dar es Salaam, Tanzania.MethodsThis study design prospectively evaluated the intervention as a whole, and offered a before-and-after comparison of the impact of the main training. We measured changes in microbiological cleanliness [Aerobic Colony Counts (ACC) and presence of Staphylococcus aureus] using dipslides, and physical cleaning action using gel dots. These were analysed with descriptive statistics and logistic regression models. We used qualitative (focus group discussions, in-depth interviews, and semi-structured observation) and quantitative (observation checklist) tools to measure why and how the intervention worked. We describe these findings across the themes of adaptation, fidelity, dose, reach and context.ResultsMicrobiological cleanliness improved during the study period (ACC pre-training: 19%; post-training: 41%). The odds of cleanliness increased on average by 1.33 weekly during the pre-training period (CI = 1.11–1.60), and by 1.08 (CI = 1.03–1.13) during the post-training period. Cleaning action improved only in the pre-training period. Detection of S. aureus on hospital surfaces did not change substantially. The intervention was well received and considered feasible in this context. The major pitfalls in the implementation were the limited number of training sessions at the hospital level and the lack of supportive supervision. A systems barrier to implementation was lack of regular cleaning supplies.ConclusionsThe evaluation suggests that improvements in microbiological cleanliness are possible using this intervention and can be sustained. Improved microbiological cleanliness is a key step on the pathway to infection prevention in hospitals. Future research should assess whether this bundle is cost-effective in reducing bacterial and viral transmission and infection using a rigorous study design.

Pan Traps for Tracking Honey Bee Activity-Density: A Case Study in Soybeans.

To study how honey bees utilize forage resources and guide pollination management plans in crops, a multitude of methods have been developed, but most are time consuming, costly, and require specialized skills. Colored pan traps for monitoring activity-density are a simple, efficient, and cost-effective alternative; however, their usefulness for studying honey bees is not well described. We examined if trap color, location within a field, and the presence of managed colonies affected estimates of honey bee activity-density within soybean fields. Soybeans are visited by pollinators but do not require these visits for seed development. Pan traps, especially those colored blue, captured more honey bees when colonies were present. There were no differences in activity-density based on placement of traps within a field nor with increasing distance from colonies. Throughout the season, activity-density in soybeans was constant but tripled after soybean ceased blooming, suggesting spikes in pan trap captures may indicate periods of forage scarcity. Activity-density did not correlate with the population size of worker bees at a site, but did correlate with number of colonies present. We conclude that pan traps can be useful for assessing honey bee activity, particularly for estimating colony presence and identifying times of forage scarcity.

Defining spring foraging habitat and prioritization of conservation sites for Tricolored Blackbirds in California, USA

Abstract The Tricolored Blackbird (Agelaius tricolor) is a range-restricted, colonial-nesting species in decline. Colonies include tens of thousands of individuals that forage in the surrounding landscape, at times commuting miles between nesting and foraging grounds. We explored the role of landscape composition on colony occupancy and mapped core and potential spring foraging habitat in California, USA. We used observations of spring Tricolored Blackbird nesting colonies from 2008, 2011, and 2014 and characterized changes in the surrounding landscape during an extended drought. Then, we constructed occurrence and abundance models in order to map core foraging habitat across 4 ecoregions in California. Finally, we used simulated land cover changes to identify potential habitat under restoration scenarios. Across the 3 survey years, surface water declined over time at unoccupied colony locations but remained stable at occupied colony locations, confirming that permanent surface water was a critical feature of persistent Tricolored Blackbird colonies. Average percent cover of nearly all land cover types suitable for foraging, as well as frequency of dairies and median NDVI, were all higher in current or historical colony sites than elsewhere. The proportion of surrounding alfalfa, grasslands, and surface water were the elements of foraging habitat best able to predict Tricolored Blackbird early breeding season colony presence and colony size. Core foraging habitat covered over 6 million acres in the study region, but only 18% was occupied in 2014. This result suggests a need to study additional factors determining colony occurrence and persistence, such as landscape connectivity, distributions of nesting substrates, and risk from predators. The vast majority (93.1%) of Tricolored Blackbird core habitat occurred on private land; therefore, saving the species will require engagement and partnership with private landowners.

Threshold responses of grassland and sagebrush birds to patterns of disturbance created by an ecosystem engineer

Burrowing mammals play a role in rangeland disturbance worldwide, enhancing habitat for certain species while negatively affecting others. However, little is known concerning effects of disturbance spatial pattern on co-occuring fauna. In the North American Great Plains, colonial black-tailed prairie dogs (Cynomys ludovicianus) may enhance habitat for one suite of birds while degrading habitat for others. We examined the influence of prairie dogs on birds in a mosaic grassland–shrubland landscape. We evaluated how birds associated with shortgrass, midgrass, and sagebrush (Artemisia spp.) plant communities respond to spatial pattern of prairie dog disturbance and identified thresholds where abundance changes. We surveyed bird abundance on prairie dog colonies of varying sizes and shapes, across colony edges into undisturbed habitat, and within undisturbed sagebrush in northeastern Wyoming. We modeled species responses to colony presence, distance to colony edge, and total area and edge density of colonies at four spatial scales (100 m, 225 m, 500 m, 1000 m). Sagebrush specialists like Brewer’s sparrow (Spizella breweri) and sage thrasher (Oreoscoptes montanus) were 4.5 times more abundant in undisturbed shrublands. Conversely, the shortgrass-specialist mountain plover (Charadrius montanus) was abundant on colonies but showed a non-linear response to colony edge, increasing in abundance up to 600 m from edges then declining further towards colony cores. While some species may be broadly intolerant to disturbance, disturbance-dependent birds can display a “goldilocks syndrome” relative to disturbance size. As such, management for multiple species of conservation concern can be optimized relative to other goals by identifying thresholds associated with the effect of disturbance.

Significant decline of endangered Antipodes Island penguins: Is extreme weather an additional impact?

Abstract Worldwide, most crested penguin species (Eudyptes spp.) are in decline. New Zealand's subantarctic Antipodes Islands are of international significance for erect‐crested (Eudyptes sclateri) and rockhopper (Eudyptes filholi) penguins. Between 1995 and 2011, a 23% decline was recorded in the two penguin species on the Antipodes Islands. In October 2014, nest abundance counts on Antipodes Island were undertaken to determine if this decline was continuing, particularly in light of a significant storm event that hit the Antipodes area in January 2014 causing massive landslides during the penguin breeding season. All penguin colonies ground counted in 2011 were preferentially ground counted in 2014 or, if time or weather did not allow, were checked with binoculars to confirm colony presence or absence. Seventy‐three per cent of the colonies and the equivalent of 82% of all nests counted in 2011 were recounted in 2014. Overall, there was a 19% decline in erect‐crested penguin nests between 2011 and 2014. Rockhopper penguins showed a slight increase (2.6%). Landslides affected 11% of the main islands’ land area and 44% of surveyed nesting colonies. Erect‐crested penguin colonies with approximately 75% or greater of their area impacted by landslides showed a significantly greater decline than unaffected or only partially impacted colonies. Landslides showed a minimal effect on rockhopper nest numbers. There continues to be a significant decline of erect‐crested penguins at the Antipodes Islands. An increasing occurrence of extreme weather events are predicted with climate change and have the potential to increase land‐based flooding and landslides, adding additional impacts to terrestrial breeding marine species. Greater understanding of what is causing erect‐crested penguin decline is needed to prevent this endangered species from extinction.

Plant pathogenic fungi decrease in soil inhabited by seed-dispersing ants

One benefit of animal-mediated seed dispersal is that dispersers may deposit the seeds in protected or enriched microhabitats favorable for seedling survival. Ants are a common seed disperser, and seeds deposited in soils occupied by ant colonies have higher germination and survival rates, benefits attributed to enriched soil conditions and protection from seed predators and fire. Fungal pathogens also devastate young plants, and fungal protection may be an additional benefit of ant-mediated seed dispersal. Ants secrete anti-microbial compounds that appear to suppress the spread of fungal and bacterial diseases in ant colonies, and they confer fungal pathogen protection to the seeds they handle. If fungal protection is a potential benefit of ant-mediated dispersal, we expected that ant-occupied soil (soils inhabited by ants for colony nesting) would contain fewer phytopathogenic fungi than proximate soils without ant nests. We tested this hypothesis with ant soils from the Aphaenogaster rudis complex; the dominant seed-dispersing ants in eastern deciduous forests. We investigated published Aphaenogaster soil fungi data and conducted our own metataxonomic analysis of ant-occupied and unoccupied soils to identify phytopathogenic fungi and investigate whether ant colony presence corresponds with reduced plant fungal pathogens in the soil. We found reduced phytopathogenic fungi presence and richness in soils containing ant colonies as compared to nearby control soils indicating that the presence of ant colonies was concomitant with a reduction in plant pathogens. Ant chemical secretions protect colonies from microbial pathogens in the crowded, moist nest conditions. Plant seeds also thrive in these locations and environments, where they are subject to phytopathogenic fungi. Multiple hypotheses explain the benefits ant-mediated seed dispersal provides plants, but heretofore, fungal protection has been suggested, but not tested. Soil occupation by ants corresponds to phytopathogenic fungi declines, which have the potential to benefit plants.

Nutrient subsidy indicators predict the presence of an avian mobile-link species

Island ecosystems can be inordinately dependent on avian nutrient subsidies because of their isolation from external nutrient pools. We investigated relationships between several nutrient subsidy indicators and the presence of Torresian Imperial-Pigeon (TIP, Ducula spilorrhoa) breeding colonies in island forests of northeast Australia. The following nutrient subsidy indicators were measured in island forest soil and leaf samples: nutrient origin (δN15 and δC13); total carbon (C), nitrogen (N), and phosphorus (P) levels; and nutrient quality (C:N:P ratios). Random Forest models were used to determine the relative importance of nutrient subsidy indicators for classifying island forests as ‘TIP colony present’ or ‘TIP colony absent’. Total P was the most important soil nutrient subsidy indicator, while δN15 was the most important leaf nutrient subsidy indicator. Furthermore, in both soil and leaves, δN15 enrichment and N and P levels increased as the probability of TIP colony presence increased. Measures of nutrient quality also implied plant growth rates were higher in island forests with increased likelihood of TIP colony presence. Torresian Imperial-Pigeons should be classified as an avian mobile-link species with an important role in island ecosystem functioning, encouraging further investigation of the direct and indirect effects associated with TIP nutrient subsidies. This research highlights the importance of understanding the local-scale connectivity processes that underpin the longer distance movements of inter-continental migrants for effective ecosystem management.

Forest stream biota carbon : nitrogen ratios are unaffected by nutrient subsidies from breeding Westland petrels (Procellaria westlandica)

Stable isotope studies have repeatedly shown marine nutrient incorporation from seabirds, anadromous fish and tidal wrack into terrestrial and freshwater ecosystems. However, little is known about the physiological consequences of marine-derived nutrient subsidies. Protein content and lipid storage are important physiologically, and the C:N ratio is a widely used proxy that reflects changes in these quantities. In this study we tested the response of C:N ratios in stream biota to the presence of marine-derived nutrients from Westland petrels, a forest breeding seabird. Samples of different stream invertebrate functional feeding groups, predatory freshwater fish, coarse particulate organic matter and riparian soil and vegetation came from four reference streams and four streams with a wide range of seabird densities. Samples were analysed for percentage C, percentage N and δ15N using isotope ratio mass spectrometry. The data were tested against petrel colony size, stream size and distance from colony to sampling site. Despite increased δ15N accompanying petrel presence (as reported previously), Westland petrels had no effect on stream biota C:N ratios, regardless of colony presence or absence or colony size. Despite the nutrients provided by petrels, we conclude that petrel N replaced rather than enhanced non-marine N in these stream ecosystems.

Using beaver works to estimate colony activity in boreal landscapes

ABSTRACTBeaver ponds and beaver‐impounded vegetation are indicators of past or present beaver activity that can be detected from aerial photography. A method to quantitatively relate these beaver works with the density of active beaver colonies could benefit beaver management, particularly in areas lacking beaver population data. We compared historical maps (1961–2006) of beaver works at Voyageurs National Park, Minnesota, USA with concurrent aerial surveys of beaver colonies. We tested 2 landscape‐scale models of beaver colony density previously developed for a period of beaver population expansion (1940–1986), but they failed to predict colony density after 1986, a period of declining beaver population. We developed a new landscape‐scale regression, calculating that 2.15% of the landscape would be flooded by every 100 additional beaver colonies (R2 = 0.53, P = 0.027). Classification tree analysis of individual pond sites showed that open water pond and impounded marsh area were the primary predictors of beaver colony presence or absence, but that the classification trees were far better at identifying inactive sites (>93% correct) than active sites (35–38% correct). The area of open water in beaver ponds is a good but not perfect indicator of beaver activity that can be used by wildlife managers as a landscape‐scale indicator of beaver colony density. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Influence of egg oiling on colony presence of ring-billed gulls

Egg oiling is a form of management in which bird eggs are coated with mineral or corn oil, preventing gas exchange through the shell and killing embryos. Unlike other nest- disturbance techniques, egg oiling reportedly precludes colony abandonment and, thus, can be advantageous when managers wish to limit dispersal within the breeding season to other locations while stabilizing the population or reducing productivity. However, unintended, indirect effects of egg oiling are not well-characterized. We evaluated the influence of egg oiling on ring-billed gulls (Larus delawarensis) within the Lake Champlain basin, Vermont, during the nesting season to determine whether egg oiling affected colony presence of adults. We radio- marked 58 ring-billed gulls captured on Young Island during 2008 to 2009 and treated all ring-billed gull nests in the colony with egg oiling except for 50% of the nests of radio-marked gulls (control group). Using a radio receiver with automated data logger, we documented the presence of ring-billed gulls at the colony throughout the breeding season. We examined effects of treatment (nests oiled or control), sex, reproductive period (pre- and post-hatch), year, and interactive effects on colony presence (i.e., the proportion of nights ring-billed gulls spent at Young Island). Although we found no effect of treatment, sex, or interactive effects on colony presence, colony presence was 87% greater in the pre-hatch period, presumably due to behavioral mechanisms related to incubation or foraging. Overall colony presence was 118% greater in 2009 than in 2008, potentially a consequence of increased colony disturbance in 2008. We suggest that egg oiling does not influence colony presence of ring-billed gulls within the breeding season.

Fine‐scale impacts on avian biodiversity due to a despotic species, the bell miner (Manorina melanophrys)

AbstractBell miners (Manorina melanophrys; Meliphagidae) are a highly social and very aggressive honeyeater. They are despotic and cooperate in the defence of their territories against other bird species, leading to the almost complete exclusion of other avifauna from miner‐occupied regions. This study aimed to resolve some of the fine‐scale effects of bell miner aggression on avian diversity both within and adjacent to colonies to determine the true impact of a colony on local avifaunal abundance. Three areas, distributed throughout the range of the bell miner, were surveyed across both non‐breeding and breeding seasons to assess the temporal and spatial impacts of bell miner aggression on other bird species. Bell miner colonies were found to occupy very clearly defined areas and had the expected negative impact on avian diversity within their colony. The effects of bell miner colony presence on abundance and richness of avian species were found to cease at the colony boundary, with both recovering to normal levels immediately outside the bell miner colony. Whether bell miners were breeding or not, and irrespective of the amount of vegetation coverage, bell miner colonies were found to have relatively marginal impacts on avian richness and abundance. No impact of colony presence/absence was found on the richness or abundance of the avian species that dwell in the undergrowth, with some evidence that these species were actually more common at the colony edge. Our results demonstrate that the influence of bell miner colony presence upon avian biodiversity is restricted to the confines of the colony and does not radiate outwards into the surrounding habitat. Colony presence influences, therefore, have implications when considering the impact of bell miner behaviour on the diversity of insectivorous birds and processes, most notably the propagation of Bell Miner Associated Dieback.

Application of random forest algorithm for studying habitat selection of colonial herons and egrets in human‐influenced landscapes

AbstractUnderstanding the mechanisms of habitat selection is fundamental to the construction of proper conservation and management plans for many avian species. Habitat changes caused by human beings increase the landscape complexity and thus the complexity of data available for explaining species distribution. New techniques that assume no linearity and capable to extrapolate the response variables across landscapes are needed for dealing with difficult relationships between habitat variables and distribution data. We used a random forest algorithm to study breeding‐site selection of herons and egrets in a human‐influenced landscape by analyzing land use around their colonies. We analyzed the importance of each land‐use variable for different scales and its relationship to the probability of colony presence. We found that there exist two main spatial scales on which herons and egrets select their colony sites: medium scale (4 km) and large scale (10–15 km). Colonies were attracted to areas with large amounts of evergreen forests at the medium scale, whereas avoidance of high‐density urban areas was important at the large scale. Previous studies used attractive factors, mainly foraging areas, to explain bird‐colony distributions, but our study is the first to show the major importance of repellent factors at large scales. We believe that the newest non‐linear methods, such as random forests, are needed when modelling complex variable interactions when organisms are distributed in complex landscapes. These methods could help to improve the conservation plans of those species threatened by the advance of highly human‐influenced landscapes.

Molecular characterization and pathogenicity of Colletotrichum sp. from guava

Guava (Psidium guajava) fruit is vulnerable to postharvest diseases, such as anthracnose. In the present study, molecular characterisation and pathogenicity of Colletotrichum associated with antharcnose disease of guava fruit were conducted. From anthracnose lesion of guava, 20 isolates were successfully recovered. Based on colony colours, conidia, appressoria and presence or absence of setae, and ITS regions and ß-tubulin gene sequences, the isolates were identified as Colletotrichum gloeosporioides. Phylogenetic analysis based on combined data-sets using neighbour-joining method showed that C. gloeosporioides isolates did not group with C. gloeosporioides epitype strain, and thus the isolates were referred to as C. gloeosporioides species complex or C. gloeosporioides sensu lato. Pathogenicity tests using wounded treatment showed that C. gloeosporioides isolates from guava were pathogenic causing anthracnose on the fruits. The present study showed that C. gloeosporioides sensu lato is the most common species causing antharcnose disease of guava fruit.

Ecosystem engineering and predation: the multi-trophic impact of two ant species

1. Ants are ubiquitous ecosystem engineers and generalist predators and are able to affect ecological communities via both pathways. They are likely to influence any other terrestrial arthropod group either directly or indirectly caused by their high abundance and territoriality. 2. We studied the impact of two ant species common in Central Europe, Myrmica rubra and Lasius niger, on an arthropod community. Colony presence and density of these two ant species were manipulated in a field experiment from the start of ant activity in spring to late summer. 3. The experiment revealed a positive influence of the presence of one ant colony on densities of decomposers, herbivores and parasitoids. However, in the case of herbivores and parasitoids, this effect was reversed in the presence of two colonies. 4. Generally, effects of the two ant species were similar with the exception of their effect on Braconidae parasitoid densities that responded positively to one colony of M. rubra but not of L. niger. 5. Spider density was not affected by ant colony manipulation, but species richness of spiders responded positively to ant presence. This effect was independent of ant colony density, but where two colonies were present, spider richness was significantly greater in plots with two M. rubra colonies than in plots with one colony of each ant species. 6. To test whether the positive ecosystem engineering effects were purely caused by modified properties of the soil, we added in an additional experiment (i) the soil from ant nests (without ants) or (ii) unmodified soil or (iii) ant nests (including ants) to experimental plots. Ant nest soil on its own did not have a significant impact on densities of decomposers, herbivores or predators, which were significantly, and positively, affected by the addition of an intact nest. 7. The results suggest an important role of both ant species in the grassland food web, strongly affecting the densities of decomposers, herbivores and higher trophic levels. We discuss how the relative impact via bottom-up and top-down effects of ants depends on nest density, with a relatively greater top-down predatory impact at higher densities.

Ants accelerate succession from mountain grassland towards spruce forest

AbstractQuestion: What is the role of mound‐building ants (Lasius flavus) in successional changes of a grassland ecosystem towards a spruce forest?Location: Slovenské Rudohorie Mountains, Slovakia; ca. 950 m a.s.l. near the Obrubovanec point (1020 m a.s.l.; 48°41′N, 19°39′E).Methods: Both chronosequence data along a successional gradient and temporal data from long‐term permanent plots were collected on ants, spruce establishment, and vegetation structure, together with additional data on spruce growth.Results: There are more spruce seedlings on ant mounds (4.72 m−2) than in the surrounding vegetation (0.81 m−2). Spruce seedlings grow faster on these mounds compared to surrounding areas. The first colonization wave of seedlings was rapid and probably occurred when grazing prevailed over mowing. Ant colony presence, mound volume, and plant species composition change along the successional gradient. Mounds become bigger when partly shaded but shrink in closed forest, when ant colonies disappear. Shade‐tolerant acidophylic species replace grassland plants both on the mounds and in surrounding areas.Conclusions: The massive occurrence of Lasius flavus anthills contributes to a runaway feedback process that accelerates succession towards forest. The effect of ants as ecosystem engineers is scale‐dependent: although they stabilize the system at the scale of an individual mound, they may destabilize the whole grassland system over a longer time scale if combined with changes in mowing regime.