Meteorological factors associated with the timing and abundance of Hymenoscyphus fraxineus spore release

The ascomycete Hymenoscyphus fraxineus has spread across most of the host range of European ash with a high level of mortality, causing important economic, cultural and environmental effects. We present a novel method combining a Monte-Carlo approach with a generalised additive model that confirms the importance of meteorology to the magnitude and timing of H. fraxineus spore emissions. The variability in model selection and the relative degree to which our models are over- or under-fitting the data has been quantified. We find that both the daily magnitude and timing of spore emissions are affected by meteorology during and prior to the spore emission diurnal peak. We found the daily emission magnitude has the strongest associations to weekly average net radiation and leaf moisture before the emission, soil temperature during the day before emission and net radiation during the spore emission. The timing of the daily peak in spore emissions has the strongest associations to net radiation both during spore emission and in the day preceding the emission. The seasonal peak in spore emissions has a near-exponential increase/decrease, and the mean daily emission peak is approximately Gaussian.

Managing Risks from Invasive Marine Species: Is Post-Border Management Feasible?

<p>Non-indigenous marine species are a major threat to marine environments and economies globally. This thesis examines whether management of pest organisms post-border (i.e, after they have established in New Zealand) is feasible in the marine environment, using the non-indigenous Asian kelp Undaria pinnatifida as a model organism. Background information on Undaria in Chapter 2 recognises the paucity of information on Undaria's impacts. Hence, Chapter 3 investigates ecological effects from Undaria in a low shore rocky habitat. Although negligible effects were described, the uncertainty in extrapolating findings to other places and times means that the precautionary principle should be applied by managers, and 'worst-case' impacts assumed. Chapter 4 investigates mechanisms for Undaria's natural dispersal, and describes strategies based on spore release and sporophyte drift that may lead to spread over scales of metres to kilometres. This work highlights the importance of human transport vectors (especially vessels and aquaculture) in the post-border spread of Undaria at regional and national scales. Hence, a case study in Chapter 5 describes aquaculture activities that could be vectors for spread of Undaria in New Zealand, and presents criteria for identifying present and future high risk pathways. Chapters 6 and 7 describe methods to reduce the accidental transport of Undaria and other biofouling pests with aquaculture, with a focus on mussel farming. Treatments based on water blasting, air drying and freshwater immersion provide low cost options for equipment such as floats and rope. For treatment of mussel seed-stock, immersion in dilute (4%) acetic acid (the active ingredient in vinegar) is identified as a method that could eliminate Undaria and other soft-bodied fouling organisms without resulting in an unacceptable level of mussel mortality. Chapter 8 proposes a risk-based framework for setting post-border management priorities based on the feasibility, benefits and costs of risk reduction. This chapter elucidates how knowledge generated from research in Chapters 2-7 can be used in a biosecurity risk management context. It shows that effective management post-border is possible even when pest organisms become relatively well established, and that the benefits gained from even limited successes have the potential to greatly outweigh the consequences of uncontrolled invasion. However, as unwanted species become increasingly widespread, management will become increasingly focussed on the protection of specific values. Chapter 9 extends some of the ideas proposed in Chapter 8, and considers a broad postborder management framework for marine pests. A comprehensive system should consist of vector management, surveillance, and incursion response that targets particular pests or suites of functionally similar species (e.g., biofouling organisms), coupled with generic vector management approaches that aim to reduce humanmediated transport of all organisms at a national scale. New Zealand's geographic isolation and low population, hence relatively low level of vector activity, makes the management of human-mediated pathways of spread entirely feasible in many circumstances. Hence, while there are clearly many challenges in the post-border management of marine pests, this is nonetheless a realistic goal, and probably moreso in New Zealand than in any other country in the world.</p>

Managing Risks from Invasive Marine Species: Is Post-Border Management Feasible?

<p>Non-indigenous marine species are a major threat to marine environments and economies globally. This thesis examines whether management of pest organisms post-border (i.e, after they have established in New Zealand) is feasible in the marine environment, using the non-indigenous Asian kelp Undaria pinnatifida as a model organism. Background information on Undaria in Chapter 2 recognises the paucity of information on Undaria's impacts. Hence, Chapter 3 investigates ecological effects from Undaria in a low shore rocky habitat. Although negligible effects were described, the uncertainty in extrapolating findings to other places and times means that the precautionary principle should be applied by managers, and 'worst-case' impacts assumed. Chapter 4 investigates mechanisms for Undaria's natural dispersal, and describes strategies based on spore release and sporophyte drift that may lead to spread over scales of metres to kilometres. This work highlights the importance of human transport vectors (especially vessels and aquaculture) in the post-border spread of Undaria at regional and national scales. Hence, a case study in Chapter 5 describes aquaculture activities that could be vectors for spread of Undaria in New Zealand, and presents criteria for identifying present and future high risk pathways. Chapters 6 and 7 describe methods to reduce the accidental transport of Undaria and other biofouling pests with aquaculture, with a focus on mussel farming. Treatments based on water blasting, air drying and freshwater immersion provide low cost options for equipment such as floats and rope. For treatment of mussel seed-stock, immersion in dilute (4%) acetic acid (the active ingredient in vinegar) is identified as a method that could eliminate Undaria and other soft-bodied fouling organisms without resulting in an unacceptable level of mussel mortality. Chapter 8 proposes a risk-based framework for setting post-border management priorities based on the feasibility, benefits and costs of risk reduction. This chapter elucidates how knowledge generated from research in Chapters 2-7 can be used in a biosecurity risk management context. It shows that effective management post-border is possible even when pest organisms become relatively well established, and that the benefits gained from even limited successes have the potential to greatly outweigh the consequences of uncontrolled invasion. However, as unwanted species become increasingly widespread, management will become increasingly focussed on the protection of specific values. Chapter 9 extends some of the ideas proposed in Chapter 8, and considers a broad postborder management framework for marine pests. A comprehensive system should consist of vector management, surveillance, and incursion response that targets particular pests or suites of functionally similar species (e.g., biofouling organisms), coupled with generic vector management approaches that aim to reduce humanmediated transport of all organisms at a national scale. New Zealand's geographic isolation and low population, hence relatively low level of vector activity, makes the management of human-mediated pathways of spread entirely feasible in many circumstances. Hence, while there are clearly many challenges in the post-border management of marine pests, this is nonetheless a realistic goal, and probably moreso in New Zealand than in any other country in the world.</p>

New Insights on the Sporulation, Germination, and Nutritional Profile of Gracilaria gracilis (Rhodophyta) Grown under Controlled Conditions

The red seaweed Gracilaria gracilis is a widely cultivated species known for its high agar content. It is also an important source of proteins, minerals, and vitamins. The chemical profile of seaweed depends on the cultivation methods used and the growing conditions to which they are exposed. Thus, two independent methods of sporulation and germination were tested upon Gracilaria gracilis grown in controlled conditions. During the tests, different substrates, culture media and incubation times were tested to induce cystocarp maturation. The results showed that cystocarp maturation and spore release were successful, with a visible volume increase and format change in the protruding cystocarps. Furthermore, the process of maturation to germination was accomplished, fulfilling the complete life cycle. In parallel, the nutritional profile of the biomass obtained was evaluated and compared with the nutritional values of biomass collected from the environment. Results showed no significant differences between wild specimens and cultivated ones in organic matter, ash content, lipid content, carbohydrates, or phycocolloid content. The present work, therefore, presents two simple alternative methods with potential applications in start-ups aimed at the cultivation of seaweed. Through these methods, it is possible to obtain biomass with nutritional characteristics similar to those obtained in the wild.

Infection effects of the new microsporidian species Tubulinosema suzukii on its host Drosophila suzukii

Microsporidian infections of insects are important natural constraints of population growth, often reducing lifespan, fecundity and fertility of the infected host. The recently discovered Tubulinosema suzukii infects Drosophila suzukii (spotted wing drosophila, SWD), an invasive pest of many fruit crops in North America and Europe. In laboratory tests, fitness effects on larval and adult stages were explored. High level infection after larval treatment caused up to 70% pupal mortality, a decreased lifespan and a 70% reduced oviposition of emerging adults in biparental infection clusters. A shift to higher proportion of female offspring compared to controls suggested a potential parthenogenetic effect after microsporidian infection. A clear sex-linkage of effects was noted; females were specifically impaired, as concluded from fecundity tests with only infected female parents. Additive effects were noted when both parental sexes were infected, whereas least effects were found with only infected male parents, though survival of males was most negatively affected if they were fed with T. suzukii spores in the adult stage. Although most negative effects on fitness parameters were revealed after larval treatment, infection of offspring was never higher than 4%, suggesting limited vertical transmission. For that reason, a self-reliant spread in natural SWD populations would probably only occur by spore release from cadavers or frass.

Biofilm dispersal for spore release in Bacillus subtilis

The dispersal of bacterial cells from a matured biofilm can be mediated either by active or passive mechanisms. In this issue of the Journal of Bacteriology, Nishikawa and Kobayashi demonstrate that the presence of calcium influences dispersal of spores from the pellicle biofilm of Bacillus subtilis. The authors propose that temporal heterogeneity in matrix production and chelation of calcium by dipicolinic acid in spores weakens the biofilm matrix and causes passive dispersal.

Barrier properties of fungal fruit body skins, pileipelles, contribute to protection against water loss

The permeability of intact fungal fruit body skins (pileipelles) with respect to water and oxygen was determined for the first time. Methods that have been successfully applied to plant surfaces were used to study isolated pileipelles. Mechanically isolated skins from five genera of Basidiomycota (species of Amanita, Russula, Stropharia, Tapinella, and Tricholomopsis) were mounted between two compartments simulating the inner (fruit body) and the outer (aerial) space. Fluxes of water and oxygen across the skins were measured. Water loss via intact skins differed markedly from evaporation of water from a water surface. The skins reduced water loss by factors of 10 to 30, with permeability ranging from 2.8 to 9.8 × 10−4 ms−1. Oxygen permeability was much lower and ranged from 0.8 to 6.0 × 10−6 ms−1. Chloroform-extractable substances play a minor, but significant role as transport barrier during water permeance. Water and oxygen permeability were dependent on the humidity in the aerial compartment. Higher humidity in the air increased permeability and the hydration/water content of the skins. The ecological implications include impacts to fungal growth, sporulation and spore release.

Analysis of bioaerosol emission patterns of tropical fungi in the Amazon region

&lt;p&gt;Primary biological aerosol particles (PBAP), better known as bioaerosols, are considered to play a role in atmospheric and climate influencing processes. Fungal spores, as a part of PBAP, account for a large fraction of coarse particulate matter in some ecosystems, as for example the Amazon rainforest. In such highly diverse ecosystems, fungi play key roles as mycorrhizal fungi for nutrient uptake of plants and as decomposers in nutrient and water cycling, and thus their community structure strongly influences local ecosystem conditions. Despite this relevance, fungal spore emission patterns under natural conditions and the corresponding triggering factors are not well characterized, yet. In this study, we present a laboratory and field measurement techniques to quantify and analyze bioaerosol emission patterns and the effect of precipitation on fungal spore emission.&lt;/p&gt;&lt;p&gt;For investigations under field conditions, the particle emissions of fungi (Agaricomycetes) were characterized at their site of growth in the field using an optical particle sizer and a data logger. Particle concentrations and their size distribution (0.3 to 10 &amp;#181;m), as well as the microclimatic temperature and humidity were measured in close vicinity to the fungal fruiting body. Generally, field measurements were performed over a time span of 24 h with some exceptions ranging up to 6 days. For laboratory measurements, a newly developed glass chamber system was used to measure particle emissions of fungi under controlled conditions. During the chamber measurements, the humidity and temperature conditions were varied and recorded with a datalogger. To simulate precipitation events, the fruiting bodies were sprayed with water between measurement sections and particle emissions were monitored before and after moistening.&lt;/p&gt;&lt;p&gt;First measurements of fungi under field and lab conditions showed that high humidity values were necessary to trigger fungal spore emissions. In many cases, precipitation events and the moisture status of the fungus and substrate had an influence on spore release. Based on the results of 47 field measurements, it was possible to establish a function simulating the spore emission patterns of fungi during their diurnal emission cycle. During field measurements, an emission of up to 55,000 spores per second was recorded directly at the fungus, which, according to the function, may correspond to emissions of up to 2.8 x 10&lt;sup&gt;9&lt;/sup&gt; spores per day. Chamber measurements showed that spore emissions generally started 2-3 hours after artificial moistening.&lt;/p&gt;&lt;p&gt;Increasing deforestation is expected to cause drier conditions and to increase the possibility of droughts, which will have an impact on the species composition and quantity of fungi in the Amazon. A combination of our field and lab emission data is expected to allow a new interpretation of bioaerosol emissions and composition in the Amazon, which can be used as a baseline to analyze the potential relevance of bioaerosols in regional atmosphere and climate processes.&lt;/p&gt;