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Search Results: 1 - 10 of 119282 matches for " Astrid T Groot "
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Circadian rhythms of sexual activities in moths: a review
Astrid T. Groot
Frontiers in Ecology and Evolution , 2014, DOI: 10.3389/fevo.2014.00043
Abstract: The circadian rhythm of behavior has interested many researchers in the past decades, yet amazingly little is known on the evolution of natural variation in circadian rhythms of behavior. Most research has been focused on identifying the circadian clock genes that form an intricate clock network, which turns out to be more complex with every discovery. To understand the importance of circadian rhythms of behavior in speciation, genetic analyses should be conducted on intra- and interspecific allochronic differentiation of behaviors. Many moth species show specific daily activity rhythms in their sexual activities, some species being sexually active early at night, while others are sexually active late at night. This differentiation has been suggested to have arisen to minimize communication interference between closely related species, as co-occurring and closely related species with overlapping sex pheromone blends show a temporal differentiation in their daily sexual activities. However, the genetic differentiation of this allochronic separation has barely been examined in any species so far. In this review I summarize studies conducted on timing of sexual activities in moths, and which factors have been found to influence this timing, with the aim to identify the gaps and challenges, to unravel the possible contribution of allochronic differentiation of sexual activities in moth speciation.
Host strain specific sex pheromone variation in Spodoptera frugiperda
Astrid T Groot, Melanie Marr, Gerhard Sch?fl, Sybille Lorenz, Ales Svatos, David G Heckel
Frontiers in Zoology , 2008, DOI: 10.1186/1742-9994-5-20
Abstract: Relative to intra-strain variation, the pheromone composition of the two strains differed significantly. Corn strain females contained significantly more of the second most abundant pheromone compound Z11-16:Ac (m), and significantly less of most other compounds, than rice strain females. When females were injected with PBAN before their glands were extracted, the differences between the strains were less pronounced but still statistically significant. The pheromone composition of hybrid females showed a maternal inheritance of the major component Z9-14:Ac (M) as well as of Z11-16:Ac (m). Most other compounds showed an inheritance indicating genetic dominance of the corn strain. The within-strain phenotypic correlations among the various components were consistent with their hypothesized biosynthetic pathway, and between-strain differences in the correlation structure suggested candidate genes that may explain the pheromone differences between the two strains. These include Δ9- and Δ11 desaturases, and possibly also a Δ7-desaturase, although the latter has not been identified in insects so far.The two host strains of S. frugiperda produce systematically differing female sex pheromone blends. Previously-documented geographic variation in the sexual communication of this species did not take strain identity into account, and thus may be partly explained by different strain occurrence in different regions. The finding of pheromone differences reinforces the possibility of incipient reproductive isolation among these strains, previously shown to differ in the timing of nocturnal mating activity and host plant use. Finding the genetic basis of the pheromone differences, as well as these other biological traits, will help to elucidate the role of premating isolation in the continuing differentiation of these two strains that may eventually lead to speciation.In night-flying moths, highly specific, long distance, pheromonal communication ensures that males and females can
Ostrinia revisited: Evidence for sex linkage in European Corn Borer Ostrinia nubilalis (Hubner) pheromone reception
Shannon B Olsson, Subaharan Kesevan, Astrid T Groot, Teun Dekker, David G Heckel, Bill S Hansson
BMC Evolutionary Biology , 2010, DOI: 10.1186/1471-2148-10-285
Abstract: As part of a larger study to finely map the loci responsible for pheromone communication in this species, we have reanalyzed peripheral physiology among parental, and first and second generation hybrids between the two pheromone strains using tungsten electrode electrophysiology. Our results reveal that differences in spike amplitude ratio between male pheromone-sensitive sensory neurons in O. nubilalis races are controlled, at least partially, by sex-linked genes that exhibit E-strain dominance.We propose that peripheral olfactory response in O. nubilalis may be affected both by autosomal and sex-linked genes exhibiting a cross-locus dominance effect, and suggest that the genetic basis for pheromone reception and response in the species is more closely linked than previously thought.In recent years, sensory systems have received significant attention as catalysts to establish reproductive isolation between populations [1]. Chemical signals are perhaps the most ubiquitous sensory system, mediating behaviors between systems as diverse as gametes [2], and plants [3]. The evolution of pheromone diversity is an excellent resource to evaluate the role of sensory systems in speciation, both for its prevalence among several taxa and its definitive signal [4].In insects, sex pheromones are typically blends of small numbers of volatile organic compounds (e.g. [5]). Minute changes in the ratio or identity of the blend can drastically alter the nature of the response. These characteristics result in both an extraordinary specificity in pheromone communication, as well as the potential for huge diversity in pheromone blends [4]. Sex pheromones thus provide an enticing evolutionary palette for the analysis of reproductive isolation and the development of species diversity.Perhaps the most well studied system for assessing the role of pheromone diversity in reproductive isolation is the European Corn Borer (ECB; Ostrinia nubilalis). This species consists of two sympatric races, e
Transcriptome analysis of the sex pheromone gland of the noctuid moth Heliothis virescens
Heiko Vogel, Andrew J Heidel, David G Heckel, Astrid T Groot
BMC Genomics , 2010, DOI: 10.1186/1471-2164-11-29
Abstract: To facilitate identifying sets of genes involved in a broad range of processes and to capture rare transcripts, we developed our majority of ESTs from a normalized cDNA library of Heliothis virescens pheromone glands (PG). Combining these with a non-normalized library yielded a total of 17,233 ESTs, which assembled into 2,082 contigs and 6,228 singletons. Using BLAST searches of the NR and Swissprot databases we were able to identify a large number of putative unique gene elements (unigenes), which we compared to those derived from previous transcriptomic surveys of the larval stage of Heliothis virescens. The distribution of unigenes among GO Biological Process functional groups shows an overall similarity between PG and larval transcriptomes, but with distinct enrichment of specific pathways in the PG. In addition, we identified a large number of candidate genes in the pheromone biosynthetic pathways.These data constitute one of the first large-scale EST-projects for Noctuidae, a much-needed resource for exploring these pest species. Our analysis shows a surprisingly complex transcriptome and we identified a large number of potential pheromone biosynthetic pathway and immune-related genes that can be applied to population and systematic studies of Heliothis virescens and other Noctuidae.Moth sexual communication has been a major research focus for understanding the evolution of prezygotic isolation [1-7]. This is because moth sexual communication is primarily chemical, and thus variation at the chemical level provides the basis for evolutionary change. The females produce and emit pheromone from a specialized structure, the sex pheromone gland (PG) at the tip of their abdomen [8-10], while the males perceive and respond to these pheromones from a distance [11]. Since the first identification of the sex pheromone in Bombyx mori [12], sex pheromones and attractants of about 1,600 moth species have been chemically identified [13]. Most moth pheromone components are e
Semi–Selective Fatty Acyl Reductases from Four Heliothine Moths Influence the Specific Pheromone Composition
?sa K. Hagstr?m, Marjorie A. Liénard, Astrid T. Groot, Erik Hedenstr?m, Christer L?fstedt
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0037230
Abstract: Background Sex pheromones are essential in moth mate communication. Information on pheromone biosynthetic genes and enzymes is needed to comprehend the mechanisms that contribute to specificity of pheromone signals. Most heliothine moths use sex pheromones with (Z)–11–hexadecenal as the major component in combination with minor fatty aldehydes and alcohols. In this study we focus on four closely related species, Heliothis virescens, Heliothis subflexa, Helicoverpa armigera and Helicoverpa assulta, which use (Z)–11–hexadecenal, (Z)–9–tetradecanal, and (Z)–9–hexadecenal in different ratios in their pheromone blend. The components are produced from saturated fatty acid precursors by desaturation, β–oxidation, reduction and oxidation. Results We analyzed the composition of fatty acyl pheromone precursors and correlated it to the pheromone composition. Next, we investigated whether the downstream fatty–acyl reduction step modulates the ratio of alcohol intermediates before the final oxidation step. By isolating and functionally characterizing the Fatty Acyl Reductase (pgFAR) from each species we found that the pgFARs were active on a broad set of C8 to C16 fatty acyl substrates including the key pheromone precursors, Z9–14, Z9–16 and Z11–16:acyls. When presenting the three precursors in equal ratios to yeast cultures expressing any of the four pgFARs, all reduced (Z)–9–tetradecenoate preferentially over (Z)–11–hexadecenoate, and the latter over (Z)–9–hexadecenoate. Finally, when manipulating the precursor ratios in vitro, we found that the pgFARs display small differences in the biochemical activity on various substrates. Conclusions We conclude that a pgFAR with broad specificity is involved in heliothine moth pheromone biosynthesis, functioning as a semi–selective funnel that produces species–specific alcohol product ratios depending on the fatty–acyl precursor ratio in the pheromone gland. This study further supports the key role of these in pheromone biosynthesis and emphasizes the interplay between the pheromone fatty acyl precursors and the Lepidoptera specific pgFARs in shaping the pheromone composition.
Geographic Variation in Sexual Attraction of Spodoptera frugiperda Corn- and Rice-Strain Males to Pheromone Lures
Melanie Unbehend, Sabine H?nniger, Gissella M. Vásquez, María Laura Juárez, Dominic Reisig, Jeremy N. McNeil, Robert L. Meagher, David A. Jenkins, David G. Heckel, Astrid T. Groot
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0089255
Abstract: The corn- and rice-strains of Spodoptera frugiperda exhibit several genetic and behavioral differences and appear to be undergoing ecological speciation in sympatry. Previous studies reported conflicting results when investigating male attraction to pheromone lures in different regions, but this could have been due to inter-strain and/or geographic differences. Therefore, we investigated whether corn- and rice-strain males differed in their response to different synthetic pheromone blends in different regions in North America, the Caribbean and South America. All trapped males were strain-typed by two strain-specific mitochondrial DNA markers. In the first experiment, we found a nearly similar response of corn- and rice-strain males to two different 4-component blends, resembling the corn- and rice-strain female blend we previously described from females in Florida. This response showed some geographic variation in fields in Canada, North Carolina, Florida, Puerto Rico, and South America (Peru, Argentina). In dose-response experiments with the critical secondary sex pheromone component (Z)-7-dodecenyl acetate (Z7-12:OAc), we found some strain-specific differences in male attraction. While the response to Z7-12:OAc varied geographically in the corn-strain, rice-strain males showed almost no variation. We also found that the minor compound (Z)-11-hexadecenyl acetate (Z11-16:OAc) did not increase attraction of both strains in Florida and of corn-strain males in Peru. In a fourth experiment, where we added the stereo-isomer of the critical sex pheromone component, (E)-7-dodecenyl acetate, to the major pheromone component (Z)-9-tetradecenyl acetate (Z9-14:OAc), we found that this compound was attractive to males in North Carolina, but not to males in Peru. Overall, our results suggest that both strains show rather geographic than strain-specific differences in their response to pheromone lures, and that regional sexual communication differences might cause geographic differentiation between populations.
Opportunity and Problem in Context (OPiC): A Framework for Environmental Management
David Tsetse,Wouter T. De Groot
Sustainability , 2009, DOI: 10.3390/su1010019
Abstract: Most frameworks used in the management of environmental problems focus on problem analysis and pay little or no attention to the explanation of the problem and the opportunities for solving it. The Opportunity and Problem in Context (OPiC) framework aims to be fully balanced in this respect. On a broad theoretical footing, the framework can give structure and interconnection to (i) the analysis and explanation of environmental problems by making use of parallel effect chains and norm chains, the functions and values of the environment, a breakdown of human action through lifecycle principles and explanation through fields of causally related actors, (ii) the identification of opportunities for solutions based on the problem analysis, on system concepts and on creativity enhancement, and (iii) the synthesis of this in the process of design and evaluation of solutions. The OPiC framework has been developed with a special view to developing countries but its applicability is not greatly dependent on scale and context.
Participative environmental management and social capital in Poland
A. Hunka,W. T. de Groot
Social Geography (SG) & Discussions (SGD) , 2011, DOI: 10.5194/sg-6-39-2011
Abstract: Eastern European countries, such as Poland, often illustrate social capital studies. Upon entering the European Union, social capital in Poland was seen as a problem in implementing new regulations, particularly in the field of environmental policy. Equally important, environmental issues often present a high degree of complexity – and European legislation requires multi-stakeholder involvement in decision-making processes. Thus, the dilemma: on the one hand, there is a demand to engage and consult many actors; on the other hand, the actors function in administrative culture with a ubiquitous top-down approach taken by institutional decision makers. This paper attempts to address the problem from the perspective of social capital theory. An overview of administrative culture and examples of decision-making processes shows the way decisions are currently made. We also propose a way to achieve more participative environmental management.
Participative environmental management and social capital in Poland
A. Hunka,W. T. de Groot
Social Geography Discussions , 2010, DOI: 10.5194/sgd-6-39-2010
Abstract: Eastern European countries, such as Poland, are often used as exemplary in social capital studies. Upon entering the European Union, the low social capital level in Poland posed problems with implementing new regulations, particularly in the environmental policy field. Environmental issues often present a high degree of complexity – and European legislation requires multi-stakeholder involvement in decision-making processes. Thus, the dilemma: on the one hand, there is a demand to engage and consult many actors; on the other hand, low social capital contributes to an administrative culture with a ubiquitous top-down approach taken by institutional decision-makers. The paper addresses this problem from the perspective of social capital theory. A study of administrative culture and decision-making processes shows the way decisions are currently made. We also propose a way to achieve more participative environmental management.
The Importance of Insects in Agricultural Ecosystems  [PDF]
Astrid Jankielsohn
Advances in Entomology (AE) , 2018, DOI: 10.4236/ae.2018.62006
Abstract: Sufficient food production for a growing human population has become an issue of global concern. Almost all of the world’s fertile land is currently in use and arable land areas cannot be expanded significantly. The global challenge is to secure high and quality yields and to make agricultural production environmentally compatible. Insects have been hugely successful in terms of both species richness and abundance. Insects make up the most numerous group of organisms on earth, around 66% of all animal species, and being good dispersers and exploiters of virtually all types of organic matter, can be found almost everywhere, forming an important part of every ecosystem and are vital within our food supply chains performing valuable ecosystem services. Insects have been predominantly perceived as competitors in the race for survival. Herbivorous insects damage 18% of world agricultural production. Despite this damage less than 0.5 percentage of the total number of the known insect species are considered pests. Insect pests are created through the manipulation of habitats by humans, where crops are selected for larger size, higher yields, nutritious value, and are cultivated in monocultures for maximum production. This provides a highly favourable environment for the population increase of herbivorous insects. To ensure stable crop yields we need to change the management strategies of agroecosystems. We need to manage these systems in such a way that insects performing valuable ecosystem services are also incorporated into the system. This will ensure stable, resilient and sustainable systems in a constantly changing environment and will go a long way to ensure future food security. This paper examines the important role that insects generally play in ecosystems and how the services that insects provide can improve agricultural ecosystems.
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