Variability in Azygospore Production among Entomophaga maimaiga Isolates

This study describes in vitro and in vivo azygospore production by nine isolates of Entomophaga maimaiga, a fungal pathogen of the gypsy moth, Lymantria dispar. The three E. maimaiga isolates that consistently produced azygospores in vitro were also strong producers of azygospores in vivo. However, two additional isolates that were strong azygospore producers in vivo did not produce azygospores in vitro. Isolates that produced azygospores in vitro produced both conidia and azygospores more frequently in vivo than isolates not producing azygospores in vitro. In vitro azygospore production varied over time as well as by isolate. After \u3e2 years of cold storage, while three isolates continued in vitro azygospore production, three isolates no longer produced azygospores in vitro

Comparing Two Methods for Quantifying Soil-borne Entomophaga maimaiga Resting Spores

To improve usability of methods for quantifying environmentally persistent entomophthoralean resting spores in soil, we modified and tested two methods using resting spores (azygospores) of the gypsy moth pathogen Entomophaga maimaiga. Both methods were effective for recovering resting spores at concentrations \u3e100 resting spores/g dry soil. While a modification of a method originally described by Weseloh and Andreadis (2002) recovered more resting spores than a modified method based on Percoll density gradients, the ability to estimate true densities from counts was similar for both methods. Regression equations are provided for predicting true resting spore densities from counts, with R 2 values for both methods P0.90

Emergent Fungal Entomopathogen Does Not Alter Density Dependence in a Viral Competitor

Population cycles in forest Lepidoptera often result from recurring density-dependent epizootics of entomopathogens. While these systems are typically dominated by a single pathogen species, insects are often infected by multiple pathogens, yet little is known how pathogens interact to affect host dynamics. The apparent invasion of northeastern North America by the fungal entomopathogen Entomophaga maimaiga some time prior to 1989 provides a unique opportunity to evaluate such interactions. Prior to the arrival of E. maimaga, the oscillatory dynamics of host gypsy moth, Lymantria dispar, populations were apparently driven by epizootics of a nucleopolyhedrovirus. Subsequent to its emergence, E. maimaiga has caused extensive mortality in host populations, but little is known about how it has altered multigenerational dynamics of the gypsy moth and its virus. Here we compared demographic data collected in gypsy moth populations prior to vs. after E. maimaiga\u27s invasion. We found that the recently invading fungal pathogen virtually always causes greater levels of mortality in hosts than does the virus, but fungal mortality is largely density independent. Moreover, the presence of the fungus has apparently not altered the gypsy moth–virus density-dependent interactions that were shown to drive periodic oscillations in hosts before the arrival of the fungus

Strategies for Biological Control of Invasive Insects

The most widely used of the various approaches to biological control of invasive insects is so-called “conventional” biological control, which consists in introducing natural enemies (parasitoids, predators or pathogens) that originate from the same region as the insect. This approach is particularly well-suited to controlling forest insects because they reduce the pest population directly and lastingly all over the invaded territory. In addition to providing a description of the various stages of a biological control programme, the presentation provided answers to questions often brought up about this type of biocontrol, concentrating particularly on forest tree and woody plant pests. Information supplied by two databases was presented: the BIOCAT2010 base that records all introductions of parasitoids and predators for the purpose of controlling the insects. Another base relating to the entomopathogens used against insects. Up to 2010, more than 6 000 introductions of parasitoids and predators were carried out, targeting 588 species of insects, achieving control over 172 of those insects. Approximately 55 % of these introductions targeted woody plant pests. The rate of establishment of the natural enemies and success rates were higher for woody plant pests than for other pests. The presentation compared the success rates under various production systems and for various groups of woody plants for different orders of insect pests and for different categories of natural enemies. Trends over time since the beginning of conventional biological control at the end of the 19th century were also presented, together with the economic benefits, the risks of the strategy and the measures implemented to limit the latter. Finally, the outlook and obstacles relating to future biocontrol practices in Europe were discussed

Bone marrow cell derived arginase I is the major source of allergen-induced lung arginase but is not required for airway hyperresponsiveness, remodeling and lung inflammatory responses in mice

<p>Abstract</p> <p>Background</p> <p>Arginase is significantly upregulated in the lungs in murine models of asthma, as well as in human asthma, but its role in allergic airway inflammation has not been fully elucidated in mice.</p> <p>Results</p> <p>In order to test the hypothesis that arginase has a role in allergic airway inflammation we generated arginase I-deficient bone marrow (BM) chimeric mice. Following transfer of arginase I-deficient BM into irradiated recipient mice, arginase I expression was not required for hematopoietic reconstitution and baseline immunity. Arginase I deficiency in bone marrow-derived cells decreased allergen-induced lung arginase by 85.8 ± 5.6%. In contrast, arginase II-deficient mice had increased lung arginase activity following allergen challenge to a similar level to wild type mice. BM-derived arginase I was not required for allergen-elicited sensitization, recruitment of inflammatory cells in the lung, and proliferation of cells. Furthermore, allergen-induced airway hyperresponsiveness and collagen deposition were similar in arginase-deficient and wild type mice. Additionally, arginase II-deficient mice respond similarly to their control wild type mice with allergen-induced inflammation, airway hyperresponsiveness, proliferation and collagen deposition.</p> <p>Conclusion</p> <p>Bone marrow cell derived arginase I is the predominant source of allergen-induced lung arginase but is not required for allergen-induced inflammation, airway hyperresponsiveness or collagen deposition.</p

Approximating Fixation Probabilities in the Generalized Moran Process

We consider the Moran process, as generalized by Lieberman, Hauert and Nowak (Nature, 433:312--316, 2005). A population resides on the vertices of a finite, connected, undirected graph and, at each time step, an individual is chosen at random with probability proportional to its assigned 'fitness' value. It reproduces, placing a copy of itself on a neighbouring vertex chosen uniformly at random, replacing the individual that was there. The initial population consists of a single mutant of fitness $r>0$ placed uniformly at random, with every other vertex occupied by an individual of fitness 1. The main quantities of interest are the probabilities that the descendants of the initial mutant come to occupy the whole graph (fixation) and that they die out (extinction); almost surely, these are the only possibilities. In general, exact computation of these quantities by standard Markov chain techniques requires solving a system of linear equations of size exponential in the order of the graph so is not feasible. We show that, with high probability, the number of steps needed to reach fixation or extinction is bounded by a polynomial in the number of vertices in the graph. This bound allows us to construct fully polynomial randomized approximation schemes (FPRAS) for the probability of fixation (when $r\geq 1$) and of extinction (for all $r>0$).Comment: updated to the final version, which appeared in Algorithmic

The importance of olfactory and visual cues in developing better monitoring tools for \u3ci\u3eSirex noctilio\u3c/i\u3e (Hymenoptera: Siricidae)

1. To improve the monitoring of the invasive European woodwasp, both sexes of Sirex noctilio were studied in a walk-in wind tunnel.We evaluated three trap types: unbaited traps, traps baited with a three-component pheromone lure and traps baited with a commercial Sirex kairomone lure and ultraviolet light. 2. When no lure was present, the black intercept trap caught more females than the clear jar trap. The increase in pheromone concentration from 0.1 to 1mg increased the capture of females, and not males, in the black intercept panel trap. Both of these findings suggest that the visual cues provided by the black intercept trap play an important role in attraction for females. 3. Capture rates between unbaited clear versus black intercept traps did not differ but the addition of a ultraviolet light increased trap efficacy. Intercept traps baited with light were more attractive than the commercial kairomone lure. 4. Both olfactory and visual cues were found to play important roles in the response of S. noctilio to traps. A black trap may enhance the capture of females, whereas the addition of ultraviolet light could enhance capture for both sexes. Integrating these different components may help in developing an improved species-specific trap for S. noctilio