The effects of soil moisture, soil texture, and host orientation on the ability of Heterorhabditis bacteriophora (Rhabditida: Heterorhabditidae) to infect Galleria mellonella (Lepidoptera: Pyralidae)

Abstract Entomopathogenic nematodes (EPN) demonstrate potential as a biological control for soil dwelling insects. However, edaphic factors, such as soil moisture and texture impact the efficacy of EPN on a host. The objectives were to examine the effects of soil texture and moisture on 1) the infection rate of Galleria mellonella L. by EPN and; 2) the ability of H. bacteriophora (Poinar) to move through the soil to find a host at different orientations. Soil textures consisted of sand, a sand/silt/peat mixture, and a silt/peat mixture at 50% and 100% moisture. A general linear model was used to evaluate infection rates and EPN movement. Both soil moisture (p \u3c 0.05) and texture (p \u3c 0.05) had significant effects on nematodes infection rates of G. mellonella. Texture, moisture, and host orientation did not significantly affect (p \u3e 0.05) the ability of EPN to find a host. While EPN were able to find a host within a variety of soil types, soils that held more water had higher infection rates than soils that held less water, suggesting that moisture may be a key component in facilitating infection by EPN. By understanding the factors that influence the ability of EPN to find and infect a host, improved bio-control programs using EPN can be developed

Biological control of the cherry fruit fly, Rhagoletis cerasi L. (Diptera, Tephriti-dae) by use of entomopathogenic nematodes: first experiences towards practi-cal implementation.

The use of entomopathogenic nematodes (EPN) is a promising approach to control the cherry fruit fly, Rhagoletis cerasi L.. We already demonstrated the high potential of EPN to infect larvae after leaving the cherry for pupation in the soil in laboratory and field experiments. For practice, an appli-cation technique is needed, that is both, grower- and EPN friendly. We tested a tractor mounted spray boom for treatment under the canopy area. The achieved rate of EPN in the soil met the ex-pectations. The activity of EPN in soil samples was high after application, but dropped to 60% of the initial activity within one week. Exact forecasting of larval drop from cherries is another major chal-lenge. To obtain basic data, we recorded the phenology of infestation and larval emergence on trees which were not harvested. Sequential infestation on the same cherry variety was observed and larvae dropped from individual trees for several weeks

The influence of habitat quality on the foraging strategies of the entomopathogenic nematodes Steinernema carpocapsae and Heterorhabditis megidis

Entomopathogenic nematodes (EPN) are soil-transmitted parasites and their foraging strategies are believed to range from ‘ambush’ to ‘cruise’ foragers. However, research on their behaviour has not considered the natural habitat of these nematodes. We hypothesized that EPN behaviour would be influenced by soil habitat quality and tested this hypothesis using 2 EPN species Steinernema carpocapsae (an ‘ambusher’) and Heterorhabditis megidis (a ‘cruiser’) in 2 contrasting habitats, sand and peat. As predicted from previous studies, in sand most S. carpocapsae remained at the point of application and showed no taxis towards hosts, but in peat S. carpocapsae dispersed much more and showed a highly significant taxis towards hosts. H. megidis dispersed well in both media, but only showed taxis towards hosts in sand. In outdoor mesocosms in which both species were applied, S. carpocapsae outcompeted H. megidis in terms of host finding in peat, whereas the opposite was true in sand. Our data suggest that these 2 EPN may be habitat specialists and highlight the difficulties of studying soil-transmitted parasites in non-soil media

Field evaluation of entomopathogenic nematodes against orchard pests

Survival of pest in micro-plot trials (container studies) or field plot trials was monitored after exposure to commercially used EPN strains. Experimental plots were artificially infested with pest larvae that naturally burrowed into the soil for diapause. Either larval mortality or adult emergence, was assessed to estimate the control effect of the EPN treatment. Here we present preliminary results from three ongoing projects

Extragalactic Planetary Nebulae: Observational Challenges & Future Prospects

The study of extragalactic planetary nebulae (EPN) is a rapidly expanding field. The advent of powerful new instrumentation such as the PN spectrograph has led to an avalanche of new EPN discoveries both within and between galaxies. We now have thousands of EPN detections in a heterogeneous selection of nearby galaxies and their local environments, dwarfing the combined galactic detection efforts of the last century. Key scientific motivations driving this rapid growth in EPN research and discovery have been the use of the PNLF as a standard candle, as dynamical tracers of their host galaxies and dark matter and as probes of Galactic evolution. This is coupled with the basic utility of PN as laboratories of nebula physics and the consequent comparison with theory where population differences, abundance variations and star formation history within and between stellar systems informs both stellar and galactic evolution. Here we pose some of the burning questions, discuss some of the observational challenges and outline some of the future prospects of this exciting, relatively new, research area as we strive to go fainter, image finer, see further and survey faster than ever before and over a wider wavelength regimeComment: 4 pages, no figures, LaTeX, to be published in Proceedings of the ESO workshop on Planetary Nebulae beyond the Milky Way held at ESO, Garching, May 19-21, 200

Dispersal and Repulsion of Entomopathogenic Nematodes to Prenol.

Chemosensory cues are crucial for entomopathogenic nematodes (EPNs)-a guild of insect-killing parasitic nematodes that are used as biological control agents against a variety of agricultural pests. Dispersal is an essential element of the EPN life cycle in which newly developed infective juveniles (IJs) emerge and migrate away from a resource-depleted insect cadaver in order to search for new hosts. Emergence and dispersal are complex processes that involve biotic and abiotic factors, however, the elements that result in EPN dispersal behaviors have not been well-studied. Prenol is a simple isoprenoid and a natural alcohol found in association with EPN-infected, resource-depleted insect cadavers, and this odorant has been speculated to play a role in dispersal behavior in EPNs. This hypothesis was tested by evaluating the behavioral responses of five different species of EPNs to prenol both as a distal-chemotactic cue and as a dispersal cue. The results indicate that prenol acted as a repulsive agent for all five species tested, while only two species responded to prenol as a dispersal cue

Heterorhabditis, Steinernema and their bacterial symbionts - lethal pathogens of insects

The entomopathogenic nematodes (EPN) Heterorhabditis and Steinernema together with their symbiont bacteria Photorhabdus and Xenorhabdus, respectively, are obligate and lethal parasites of insects. EPN can provide effective biological control of some important lepidopteran, dipteran and coleopteran pests of commercial crops and they are amenable to large-scale culture in liquid fermentors. They are unique among rhabditids in having a symbiotic relationshipwith an enteric bacterium species. The bacterial symbiont is required to kill the insect host and to digest the host tissues, thereby providing suitable nutrient conditions for nematode growth and development. This review describes the general biology of EPN and their symbionts and gives an overview of studies to date on EPN biodiversity, biogeography and phylogeny. The impetus for research in EPN and their symbionts has come about because of their biological control potential, with much of the focus in EPN research having been on applied aspects relating to pest control. However EPN and their symbionts are increasinglybeing viewed as exciting subjects for basic research in the areas of ecology, biodiversity, evolution, biochemistry, symbiosis and molecular genetics. Much progress has been made over the past 20 years in our understanding of the basic biology and genetics of EPN and their symbionts. We are now entering a new phase in which the tools of molecular genetics are being increasingly used to address a range of biological questions in EPN research. The knowledge gained from this endeavour should ensure that EPN will become even more effective biopesticides and should also ensure that EPN and their symbionts gain prominence as unique and intrinsically interesting biological systems

A reexamination of end-point and rebound nystagmus in normals.

In order to detail the characteristics of end-point (EPN) and rebound nystagmus (RN), two series of experiments were performed with infrared oculography for measurement of horizontal eye movements. Experiment 1 consisted of EPN recordings during sustained lateral gaze (40° and 50°) in 20 normal subjects. Experiment 2 consisted of recordings of RN in 5 normal subjects. Nine of 20 subjects demonstrated a jerk EPN. EPN almost always appeared immediately and was sustained for 15-25 sec. In Experiment 2, RN occurred in 5 of the 5 subjects who demonstrated EPN. The mean amplitude of RN was always less than that of EPN, and decayed over a 5-10-sec time period. The experiment demonstrated that RN can be evoked in normals even when a fixation target, in a fully lit room, is present

cAMP and Pyk2 interact to regulate prostate cell proliferation and function.

In cultured prostate cancer cells cAMP blocks proliferation and induces neuroendocrine differentiation. Pyk2 expression inversely correlates with malignancy of prostate cancer. The aim of this study was to investigate the interaction between cAMP and Pyk2 in the prostate. EPN cells, a line derived from human normal prostate expressing Pyk2, and EPN-PKM3 cells, an EPN clone bearing a Pyk2 kinase-negative mutant, were adopted as model system. cAMP inhibited cell growth in both prostate cell lines, and activated Pyk2, but not ERK1/2, in EPN cells. cAMP treatment, abolished the activation of AKT1, an important component of the pro-survival pathway, in the EPN cells but not in EPN-PKM3 cells. Finally, upon cAMP treatment, EPN and EPN-PKM3 cells exhibited different expression patterns of HOX genes, an important network controlling cell identity. These data demonstrated for the first time that Pyk2 and cAMP interact in regulating prostate cell functions and in "keeping" prostate identity

Effectiveness of entomopathogenic nematodes in the control of Cydia pomonella larvae in Northern Italy

Since 2006, a large scale research on the effectiveness of entomopathogenic nematodes (EPN) in the control of codling moth (CM), Cydia pomonella, overwintering larvae has been performed on about 35 ha of pear orchards per year in Emilia-Romagna, Northern Italy. Steinernema carpocapsae and Steinernema feltiae activity was checked after spray applications of EPNs to the trunk and branches. In 2006, the treatment was applied either in spring or in autumn at different doses, before CM pupation; in 2007 the EPN treatment was applied only in autumn at 1.5 x 109 I.J. ha –1. Every year it was distributed by means of a conventional mist blower. The larval mortality was assessed directly on sentinel larvae in card boards on the trunks and indirectly on the eggs laid by the females of the first CM generation in spring. Moreover, each year, a trial was performed applying only S. carpocapsae on sentinel larvae with the aim of testing this nematode at suitable temperatures but at different water volumes. The CM sentinel larvae were effectively parasitized after autumnal EPN application. Moreover, the egg assessment demonstrated a good decrease in CM population in spring 2007, when EPNs had been applied at the best weather conditions (t° 12-14 °C and rain) in the previous autumn