Spruce budworm feeding and oviposition are stimulated by monoterpenes in white spruce epicuticular waxes

Monoterpenes, source of the distinctive odor of conifers, are generally considered plant defensive compounds. However, they are also known to act as long‐range insect attractants, as they are volatile and permeate forest airspaces. Moreover, they are lipid soluble and can be absorbed into plant epicuticular waxes. We test their role in short‐range host plant choice by both adult females and larvae of a folivorous forest pest (Choristoneura fumiferana). We conducted laboratory assays testing the responses of Eastern spruce budworm to an artificial monoterpene mix (α‐pinene, β‐pinene, limonene, myrcene) and to white spruce (Picea glauca) epicuticular waxes in closed arenas. Ovipositing females preferred filter paper discs treated with P. glauca waxes to controls, and preferred the waxes + monoterpenes treatment to waxes alone. However, females showed no preference between the monoterpene‐treated disc and the control when presented without waxes. Feeding larvae prefered wax discs to control discs. They also consumed discs treated with realistic monoterpene concentrations and wax preferentially over wax‐only discs, but showed no preference between extremely high monoterpene concentrations and wax‐only controls. In an insect‐free assay, P. glauca epicuticular wax decreased monoterpene volatilization. These results suggest that P. glauca waxes and realistic concentrations of monoterpenes are stimulatory to both egg‐laying females and feeding larvae, and that their effects are synergistic

Behavioural interactions between the large pine weevil, Hylobius abietis L.(Coleoptera: Curculionidae), and entomopathogenic nematodes

Entomopathogenic nematodes (EPN) of the families steinernematidae and Heterorhabditidae are a promising prospective control agent of the large pine weevil, Hylobius abietis L. (Coleoptera: Curculionidae), a major pest in Irish forestry. Applications of EPN to tree stumps in Ireland and the UK have been shown to significantly reduce adult H. abietis populations emerging from the stumps. To date however, little work had been done on the host-finding abilities of applied EPN in the field and how those EPN will interact with adult H. abietis either already on site or those that emerge from the stumps. The main objectives of this study were to investigate the behavioural interactions between two EPN species and adult H. abietis and to assess one of the methods used to investigate the impact of applied EPN strains on the indigenous EPN population. To investigate if adult H. abietis react to the presence of EPN, one thousand nematodes were applied to the head region of adult weevils and grooming responses were recorded (Chapter 3). Insects that had Steinernema carpocapsae applied on average groomed for significantly longer (44.16 seconds), than those that had Heterorhabditis downesi applied (11.33 seconds). In order to gain an insight into the possible cause of these different insect reactions to these two EPN species observations of nematode behaviour on adult H. abietis were carried out (Chapter 3). Infective juveniles (IJs) of S. carpocapsae were more likely to be observed standing or moving across the body of the insect while H. downesi IJs were more likely to be observed not moving. It is thought that this difference in behaviour has caused the differences observed in H. abietis grooming reactions. Adult H. abietis were tested to see if the presence of EPN in the substrate would alter the amount of time the insects would take to leave the area (Chapter 3). There was no difference found in the time taken to leave S. carpocapsae or H. downesi treated substrates when compared to controls. The impact of EPN presence in the substrate on H. abietis feeding was also investigated (Chapter 3). Steinernema carpocapsae was found to reduce the level of feeding on bark discs after two days when compared to controls in a choice test. This difference was not found with H. downesi or after two days post-application with either nematode species. Adult H. abietis that had been exposed to EPN did not significantly change the amount of feeding on bark discs compared to non-exposed controls (Chapter 3). In all nematode treatments, infected weevils fed more than non-infected weevils in that treatment. Weevils that died during the assay fed more than those that did not die when exposed to a low dose of H. downesi but not in the other EPN treatments. As weevils that died that were not exposed to EPN also fed more it is thought that this is not due to nematode exposure. Weevils were able to mount an immune response to both S. carpocapsae and H. downesi as encapsulated IJs of each species were found upon dissection of the exposed insects. Foraging strategies of entomopathogenic nematodes have been the subject of several studies but most have been based on simple substrates such as agar and have not reflected the ability of certain EPN species to infect hosts in cryptic field habitats. The presence of twigs in the substrate increased H. abietis larval mortality by S.carpocapsae. Insects that were able to feed differed in their mortality from those that could not in a sand/peat mixed substrate but this difference was not found in a sand only substrate (Chapter 4). The presence of twigs or insect feeding did not alter the mortality of H. abietis larvae to H. downesi in a sand substrate. The various life stages of H. abietis were tested for susceptibility to EPN infection (Chapter 4). The adult proved to be relatively insusceptible to EPN infection at low doses, with a two day exposure of 200 IJs killing none of the adult weevils exposed. Continuous exposure on filter paper at doses up to 4000 IJs resulted in a higher mortality rate. In a peat medium with an eight hour exposure mortality was different for each EPN species tested with S. carpocapsae killing more adult insects than both S. feltiae and H. downesi at all doses. When larvae and pupae were tested for EPN susceptibility it was found that larvae were highly susceptible to even low concentrations for both continuous and limited exposure. Pupae were found to be less susceptible than callow adults as insects that fully pupated during assays became readily infected by EPN (Chapter 4). The amplified fragment length polymorphism (AFLP) method for assessing levels of hybridisation between EPN strains was assessed to examine the level of accuracy possible with this method (Chapter 5). A certain level of inheritance patterns of strains of known parentage was possible but this level proved too low for statistically valid examination. The AFLP method proved to be difficult to reproduce when assessing EPN gene flow

Behavioural interactions between the large pine weevil, Hylobius abietis L.(Coleoptera: Curculionidae), and entomopathogenic nematodes

Entomopathogenic nematodes (EPN) of the families steinernematidae and Heterorhabditidae are a promising prospective control agent of the large pine weevil, Hylobius abietis L. (Coleoptera: Curculionidae), a major pest in Irish forestry. Applications of EPN to tree stumps in Ireland and the UK have been shown to significantly reduce adult H. abietis populations emerging from the stumps. To date however, little work had been done on the host-finding abilities of applied EPN in the field and how those EPN will interact with adult H. abietis either already on site or those that emerge from the stumps. The main objectives of this study were to investigate the behavioural interactions between two EPN species and adult H. abietis and to assess one of the methods used to investigate the impact of applied EPN strains on the indigenous EPN population. To investigate if adult H. abietis react to the presence of EPN, one thousand nematodes were applied to the head region of adult weevils and grooming responses were recorded (Chapter 3). Insects that had Steinernema carpocapsae applied on average groomed for significantly longer (44.16 seconds), than those that had Heterorhabditis downesi applied (11.33 seconds). In order to gain an insight into the possible cause of these different insect reactions to these two EPN species observations of nematode behaviour on adult H. abietis were carried out (Chapter 3). Infective juveniles (IJs) of S. carpocapsae were more likely to be observed standing or moving across the body of the insect while H. downesi IJs were more likely to be observed not moving. It is thought that this difference in behaviour has caused the differences observed in H. abietis grooming reactions. Adult H. abietis were tested to see if the presence of EPN in the substrate would alter the amount of time the insects would take to leave the area (Chapter 3). There was no difference found in the time taken to leave S. carpocapsae or H. downesi treated substrates when compared to controls. The impact of EPN presence in the substrate on H. abietis feeding was also investigated (Chapter 3). Steinernema carpocapsae was found to reduce the level of feeding on bark discs after two days when compared to controls in a choice test. This difference was not found with H. downesi or after two days post-application with either nematode species. Adult H. abietis that had been exposed to EPN did not significantly change the amount of feeding on bark discs compared to non-exposed controls (Chapter 3). In all nematode treatments, infected weevils fed more than non-infected weevils in that treatment. Weevils that died during the assay fed more than those that did not die when exposed to a low dose of H. downesi but not in the other EPN treatments. As weevils that died that were not exposed to EPN also fed more it is thought that this is not due to nematode exposure. Weevils were able to mount an immune response to both S. carpocapsae and H. downesi as encapsulated IJs of each species were found upon dissection of the exposed insects. Foraging strategies of entomopathogenic nematodes have been the subject of several studies but most have been based on simple substrates such as agar and have not reflected the ability of certain EPN species to infect hosts in cryptic field habitats. The presence of twigs in the substrate increased H. abietis larval mortality by S.carpocapsae. Insects that were able to feed differed in their mortality from those that could not in a sand/peat mixed substrate but this difference was not found in a sand only substrate (Chapter 4). The presence of twigs or insect feeding did not alter the mortality of H. abietis larvae to H. downesi in a sand substrate. The various life stages of H. abietis were tested for susceptibility to EPN infection (Chapter 4). The adult proved to be relatively insusceptible to EPN infection at low doses, with a two day exposure of 200 IJs killing none of the adult weevils exposed. Continuous exposure on filter paper at doses up to 4000 IJs resulted in a higher mortality rate. In a peat medium with an eight hour exposure mortality was different for each EPN species tested with S. carpocapsae killing more adult insects than both S. feltiae and H. downesi at all doses. When larvae and pupae were tested for EPN susceptibility it was found that larvae were highly susceptible to even low concentrations for both continuous and limited exposure. Pupae were found to be less susceptible than callow adults as insects that fully pupated during assays became readily infected by EPN (Chapter 4). The amplified fragment length polymorphism (AFLP) method for assessing levels of hybridisation between EPN strains was assessed to examine the level of accuracy possible with this method (Chapter 5). A certain level of inheritance patterns of strains of known parentage was possible but this level proved too low for statistically valid examination. The AFLP method proved to be difficult to reproduce when assessing EPN gene flow

Competencias en argumentación y uso de pruebas : 10 ideas clave

Incluye glosarioEl libro trata en las 5 primeras ideas la caracterización y elementos de los argumentos y el uso de las pruebas. En las 5 siguientes la argumentación en diferentes contextos: explicaciones causales, cuestiones sociocientíficas, argumentación oral y escrita y cómo promoverla y evaluarla en el aula. El libro esta dirigido al profesorado que se centra en que los alumnos razonen las respuestas.CataluñaBiblioteca de Educación del Ministerio de Educación, Cultura y Deporte; Calle San Agustín 5 -3 Planta; 28014 Madrid; Tel. +34917748000; [email protected]

Pine weevils modulate defensive behaviour in response to parasites of differing virulence

Grooming and avoidance of contaminated areas are among the behavioural defences employed by animals against parasites. Antiparasite defence behaviour is costly in terms of time, energy and/or food foregone and therefore animals are expected to modulate their defences depending on the risk of attack and/or the severity of the symptoms caused.We tested the hypothesis that an insect host invests more in defence against more virulent (more likely to cause death) than less virulent parasites. We tested avoidance and grooming of adult pine weevils, Hylobius abietis, in response to infective juveniles of two species of entomopathogenic nematodes, the more virulent Steinernema carpocapsae and less virulent Heterorhabditis downesi. Weevils avoided feeding on a substrate contaminated with S. carpocapsae but not H. downesi. Weevils also groomed more when their bodies were contaminated with S. carpocapsae than either H. downesi or water. We also made direct observations of nematodes on weevils. When equal numbers of nematodes were applied to weevils more S. carpocapsae than H. downesi moved actively on the weevil’s cuticle. Thus, the differential response of weevils to the two nematode species can be explained by the weevils detecting the more aggressive behaviour of S. carpocapsae than H. downesi, which corresponds to a higher probability of death

A genome-wide screen for dendritically localized RNAs identifies genes required for dendrite morphogenesis.

Localizing messenger RNAs at specific subcellular sites is a conserved mechanism for targeting the synthesis of cytoplasmic proteins to distinct subcellular domains, thereby generating asymmetric protein distributions necessary for cellular and developmental polarity. However, the full range of transcripts that are asymmetrically distributed in specialized cell types and the significance of their localization, especially in the nervous system, are not known. We used the EP-MS2 method, which combines EP transposon insertion with the MS2/MCP in vivo fluorescent labeling system to screen for novel localized transcripts in polarized cells, focusing on the highly branched Drosophila class IV dendritic arborization neurons. Of a total of 541 lines screened, we identified 55 EP-MS2 insertions producing transcripts that were enriched in neuronal processes, particularly in dendrites. The 47 genes identified by these insertions encode molecularly diverse proteins and are enriched for genes that function in neuronal development and physiology. RNAi-mediated knockdown confirmed roles for many of the candidate genes in dendrite morphogenesis. We propose that the transport of mRNAs encoded by these genes into the dendrites allows their expression to be regulated on a local scale during the dynamic developmental processes of dendrite outgrowth, branching, and/or remodeling

A Genome-Wide Screen for Dendritically Localized RNAs Identifies Genes Required for Dendrite Morphogenesis

Localizing messenger RNAs at specific subcellular sites is a conserved mechanism for targeting the synthesis of cytoplasmic proteins to distinct subcellular domains, thereby generating asymmetric protein distributions necessary for cellular and developmental polarity. However, the full range of transcripts that are asymmetrically distributed in specialized cell types and the significance of their localization, especially in the nervous system, are not known. We used the EP-MS2 method, which combines EP transposon insertion with the MS2/MCP in vivo fluorescent labeling system to screen for novel localized transcripts in polarized cells, focusing on the highly branched Drosophila class IV dendritic arborization neurons. Of a total of 541 lines screened, we identified 55 EP-MS2 insertions producing transcripts that were enriched in neuronal processes, particularly in dendrites. The 47 genes identified by these insertions encode molecularly diverse proteins and are enriched for genes that function in neuronal development and physiology. RNAi-mediated knockdown confirmed roles for many of the candidate genes in dendrite morphogenesis. We propose that the transport of mRNAs encoded by these genes into the dendrites allows their expression to be regulated on a local scale during the dynamic developmental processes of dendrite outgrowth, branching, and/or remodeling

Systematic analysis of YFP traps reveals common mRNA/protein discordance in neural tissues

While post-transcriptional control is thought to be required at the periphery of neurons and glia, its extent is unclear. Here, we investigate systematically the spatial distribution and expression of mRNA at single molecule sensitivity and their corresponding proteins of 200 YFP trap lines across the intact Drosophila nervous system. 97.5% of the genes studied showed discordance between the distribution of mRNA and the proteins they encode in at least one region of the nervous system. These data suggest that post-transcriptional regulation is very common, helping to explain the complexity of the nervous system. We also discovered that 68.5% of these genes have transcripts present at the periphery of neurons, with 9.5% at the glial periphery. Peripheral transcripts include many potential new regulators of neurons, glia, and their interactions. Our approach is applicable to most genes and tissues and includes powerful novel data annotation and visualization tools for post transcriptional regulation.Acknowledgments. We are very grateful to the Bloomington, Vienna, and Kyoto Drosophila Stock Centres (fly stocks), Flybase and Flymine (Lyne et al., 2007) for their reagents and open data, which were invaluable to this work. We are grateful to David Ish-Horowicz, Alfredo Castello, and members of the Davis laboratory for critical reading of the manuscript and feedback on the project. We thank Zegami Ltd. for their help, advice, and hosting the collection. This work was generously supported by a Wellcome Senior Research Fellowship (096144) and Wellcome Investigator Award (209412) to I. Davis, which funded A.I. Jarvelin, R.M. Parton, J.S. Titlow, and M.K. Thompson. Advanced microscopy facilities and technical advice as well as support to D.M. Susano Pinto were provided by Micron Oxford (https://micronoxford.com), supported by Wellcome Strategic Awards (091911 and 107457) and a Medical Research Council/Engineering and Physical Sciences Research Council/Biotechnology and Biological Sciences Research Council next-generation imaging award to I. Davis as the principal investigator. J.S. Titlolw and M.K. Thompson were supported by a Leverhulme Trust grant to I. Davis. Department of Biochemistry DPhil studentships supported J.Y. Lee and D.S. Gala. M. Kiourlappou was supported by the Biotechnology and Biosciences Research Council, grant numbers: BB/M011224/1 and BB/S507623/1, by A.G. Leventis Foundation, and by Zegami Ltd

Differential susceptibility of pine weevil, Hylobius abietis (Coleoptera: Curculionidae), larvae and pupae to entomopathogenic nematodes and death of adults infected as pupae

The large pine weevil Hylobius abietis is a serious pest of reforestation in northern Europe. Development takes place in the stumps of felled conifer trees and emerging adults feed on and kill newly planted trees. Application of entomopathogenic nematodes around tree stumps has been shown to reduce the emergence of adult weevils. In order to target application at the most susceptible stage, the susceptibility of larvae and pupae to Heterorhabditis downesi and Steinernema carpocapsae was compared in a close-contact assay on filter paper. An average of 95.8 % of larvae were killed by H. downesi and 82.1 % by S. carpocapsae while only 16.3 and 15.0 % of pupae were killed by these two species, respectively. However, many of the H. abietis that were exposed as pupae died after metamorphosis to callow adult, with mortality of pupae and callow adults combined reaching 62.5 % for H. downesi and 69.9 % for S. carpocapsae. For both nematode species significantly more insects died as larvae than as either pupae or pupae/callow adults. When pupae were exposed to infective juveniles (IJs) for 2 days and were then washed while still pupae to remove surface IJs, adults were later found to be infected indicating that IJs can infect pupae, survive metamorphosis and subsequently kill adults