We redescribe the only previously known species of Myrsidea from bulbuls, M. pycnonoti Eichler. Sixteen new species are described; they and their type hosts are: M. phillipsi ex Pycnonotus goiavier goiavier (Scopoli), M. gieferi ex P. goiavier suluensis Mearns, M. kulpai ex P. flavescens Blyth, M. finlaysoni ex P. finlaysoni Strickland, M. kathleenae ex P. cafer (L.), M. warwicki ex Ixos philippinus (J. R. Forster), M. mcclurei ex Microscelis amaurotis (Temminck), M. zeylanici ex P. zeylanicus (Gmelin), M. plumosi ex P. plumosus Blyth, M. eutiloti ex P. eutilotus (Jardine and Selby), M. adamsae ex P. urostictus (Salvadori), M. ochracei ex Criniger ochraceus F. Moore, M. borbonici ex Hypsipetes borbonicus (J. R. Forster), M. johnsoni ex P. atriceps (Temminck), M. palmai ex C. ochraceus, and M. claytoni ex P. eutilotus. A key is provided for the identification of these 17 species.

A new species

Cell-to-cell communication and long-distance signaling play a key role in the response of plants to pests, mechanical wounding, and extreme environmental conditions Here, we report on a rapid systemic signal in Arabidopsis thaliana that traveled at a rate of 84 centimeters per minute and was dependent on the respiratory burst oxidase homolog D (RbohD) gene Signal propagation was accompanied by the accumulation of reactive oxygen species (ROS) in the extracellular spaces between cells and was inhibited by the suppression of ROS accumulation at locations distant from the initiation site The rapid systemic signal was triggered by wounding, heat, cold, high-intensity light, and salinity stresses Our results reveal the profound role that ROS play in mediating rapid, long-distance, cell-to-cell propagating signals in plants

https://stke.sciencemag.org/content/sigtrans/2/84/ra45.full.pdf

The plant NADPH oxidase RBOHD mediates rapid systemic signaling in response to diverse stimuli.

Global food production must increase by 50% to meet the projected demand of the world’s population by 2050. Meeting this difficult challenge will be made even harder if climate change melts portions of the Himalayan glaciers to affect 25% of world cereal production in Asia by influencing water availability. Pest and disease management has played its role in doubling food production in the last 40 years, but pathogens still claim 10–16% of the global harvest. We consider the effect of climate change on the many complex biological interactions affecting pests and pathogen impacts and how they might be manipulated to mitigate these effects. Integrated solutions and international co-ordination in their implementation are considered essential. Providing a background on key constraints to food security, this overview uses fusarium head blight as a case study to illustrate key influences of climate change on production and quality of wheat, outlines key links between plant diseases, climate change and food security, and highlights key disease management issues to be addressed in improving food security in a changing climate.

/pdf/climate-change-plant-diseases-and-food-security-an-overview-3bhf3j81bn.pdf

Climate change, plant diseases and food security: an overview

The evolution of insecticide resistance in the peach–potato aphid, Myzus persicae

BACKGROUND The extent of urban areas is increasing around the world, and most humans now live in cities. Urbanization results in dramatic environmental change, including increased temperatures, more impervious surface cover, altered hydrology, and elevated pollution. Urban areas also host more non-native species and reduced abundance and diversity of many native species. These environmental changes brought by global urbanization are creating novel ecosystems with unknown consequences for the evolution of life. Here, we consider how early human settlements led to the evolution of human commensals, including some of the most notorious pests and disease vectors. We also comprehensively review how contemporary urbanization affects the evolution of species that coinhabit cities. ADVANCES A recent surge of research shows that urbanization affects both nonadaptive and adaptive evolution. Some of the clearest results of urban evolution show that cities elevate the strength of random genetic drift (stochastic changes in allele frequencies) and restrict gene flow (the movement of alleles between populations due to dispersal and mating). Populations of native species in cities often represent either relicts that predate urbanization or populations that established after a city formed. Both scenarios frequently result in a loss of genetic diversity within populations and increased differentiation between populations. Fragmentation and urban infrastructure also create barriers to dispersal, and consequently, gene flow is often reduced among city populations, which further contributes to genetic differentiation between populations. The influence of urbanization on mutation and adaptive evolution are less clear. A small number of studies suggest that industrial pollution can elevate mutation rates, but the pervasiveness of this effect is unknown. A better studied phenomenon are the effects of urbanization on evolution by natural selection. A growing number of studies show that plant and animal populations experience divergent selection between urban and nonurban environments. This divergent selection has led to adaptive evolution in life history, morphology, physiology, behavior, and reproductive traits. These adaptations typically evolve in response to pesticide use, pollution, local climate, or the physical structure of cities. Despite these important results, the genetic basis of adaptive evolution is known from only a few cases. Most studies also examine only a few populations in one city, and experimental validation is rare. OUTLOOK The study of evolution in urban areas provides insights into both fundamental and applied problems in biology. The thousands of cities throughout the world share some features while differing in other aspects related to their age, historical context, governmental policies, and local climate. Thus, the phenomenon of global urbanization represents an unintended but highly replicated global study of experimental evolution. We can harness this global urban experiment to understand the repeatability and pace of evolution in response to human activity. Among the most important unresolved questions is, how often do native and exotic species adapt to the particular environmental challenges found in cities? Such adaptations could be the difference as to whether a species persists or vanishes from urban areas. In this way, the study of urban evolution can help us understand how evolution in populations may contribute to conservation of rare species, and how populations can be managed to facilitate the establishment of resilient and sustainable urban ecosystems. In a similar way, understanding evolution in urban areas can lead to improved human health. For example, human pests frequently adapt to pesticides and evade control efforts because of our limited understanding of the size of populations and movement of individuals. Applied evolutionary studies could lead to more effective mitigation of pests and disease agents. The study of urban evolution has rapidly become an important frontier in biology, with implications for healthy and sustainable human populations in urban ecosystems.

Evolution of life in urban environments.

The green peach aphid, Myzus persicae (Sulzer), is a world-wide insect pest capable of infesting more than 40 plant families, including many crop species. However, despite the significant damage inflicted by M. persicae in agricultural systems through direct feeding damage and by its ability to transmit plant viruses, limited genomic information is available for this species. Sequencing of 16 M. persicae cDNA libraries generated 26,669 expressed sequence tags (ESTs). Aphids for library construction were raised on Arabidopsis thaliana, Nicotiana benthamiana, Brassica oleracea, B. napus, and Physalis floridana (with and without Potato leafroll virus infection). The M. persicae cDNA libraries include ones made from sexual and asexual whole aphids, guts, heads, and salivary glands. In silico comparison of cDNA libraries identified aphid genes with tissue-specific expression patterns, and gene expression that is induced by feeding on Nicotiana benthamiana. Furthermore, 2423 genes that are novel to science and potentially aphid-specific were identified. Comparison of cDNA data from three aphid lineages identified single nucleotide polymorphisms that can be used as genetic markers and, in some cases, may represent functional differences in the protein products. In particular, non-conservative amino acid substitutions in a highly expressed gut protease may be of adaptive significance for M. persicae feeding on different host plants. The Agilent eArray platform was used to design an M. persicae oligonucleotide microarray representing over 10,000 unique genes. New genomic resources have been developed for M. persicae, an agriculturally important insect pest. These include previously unknown sequence data, a collection of expressed genes, molecular markers, and a DNA microarray that can be used to study aphid gene expression. These resources will help elucidate the adaptations that allow M. persicae to develop compatible interactions with its host plants, complementing ongoing work illuminating plant molecular responses to phloem-feeding insects.

/pdf/genomic-resources-for-myzus-persicae-est-sequencing-snp-22yqw3gjzc.pdf

Genomic resources for Myzus persicae : EST sequencing, SNP identification, and microarray design

The 18S ribosomal DNA (rDNA) and cytochrome oxidase I region of mitochondrial DNA (mtDNA) were sequenced for 24 Xiphinema americanum-group populations sourced from a number of geographically disparate locations. Sequences were subjected to phylogenetic analysis and compared. 18S rDNA strongly suggested that only X. pachtaicum, X. simile (two populations) and a X. americanum s.l. population from Portugal were different from the other 20 populations studied, whereas mtDNA indicated some heterogeneity between populations. Phylogenetically, based on mtDNA, an apparent dichotomy existed amongst X. americanum-group populations from North America and those from Asia, South America and Oceania. Analyses of 18S rDNA and mtDNA sequences underpin the classical taxonomic issues of the X. americanum-group and cast doubt on the degree of speciation within the X. americanum-group.

Ribosomal and Mitochondrial DNA Analyses of Xiphinema americanum-Group Populations

Clones of the peach-potato aphid, Myzus persicae (Sulzer), mostly from Scotland, UK were examined using an rDNA fingerprinting technique. Eighty patterns (genotypes) were found amongst the 276 clones. A large number of clones (30%) from all sample areas in Scotland exhibited the same simple pattern, suggesting the presence of a single M. persicae clone. There was no difference in genotype distributions between M. persicae collected from brassica or potato crops, suggesting that host-adapted genotypes have no advantage in the field. Different fingerprints were randomly distributed in the environment, although clones taken from the same leaf were more often the same fingerprint. Highly distinctive fingerprints, which were more widely distributed, suggest that this technique could be used to follow individual clones. In addition to the common clonal type, multiple fingerprint bands were found over successive years, implying that, in Scotland, local overwintering asexual populations are the most common source of M. persicae in the following year.

Analysis of clonal diversity of the peach-potato aphid, Myzus persicae (Sulzer), in Scotland, UK and evidence for the existence of a predominant clone.

1. Phenotypic diversity is the fuel that powers evolution.



2. Asexual organisms rely on mutation whereas sexual organisms combine mutation with recombination.



3. Few organisms provide examples of species that are both sexual and asexual, but aphids do.



4. To examine evolution on perceptible timescales requires strong evolutionary forces and, as Darwin noted, agricultural practices provide strong selection. In the case of aphids, insecticides provide a considerable force in the elimination of genotypes.



5. Insecticide resistance in Myzus persicae (Sulzer) has arisen independently through point mutation and gene amplification on a number of occasions and at different times. Resistance to organophosphates, pyrethroids, and pirimicarb (a dimethyl carbamate) is now widespread.



6. In this paper, we examine these three elements: sexual recombination, clonal expansion, and insecticide selection in the peach–potato aphid M. persicae in relation to the evolution of insecticide resistance and survival of the fittest clone.

Micro-evolutionary change in relation to insecticide resistance in the peach–potato aphid, Myzus persicae

Background
Global commerce and human transportation are responsible for the range expansion of various insect pests such as the plant sucking aphids. High resolution DNA markers provide the opportunity to examine the genetic structure of aphid populations, identify aphid genotypes and infer their evolutionary history and routes of expansion which is of value in developing management strategies. One of the most widespread aphid species is the peach-potato aphid Myzus persicae, which is considered as a serious pest on various crops in many parts of the world. The present study examined the genetic variation of this aphid at a world scale and then related this to distribution patterns. In particular, 197 aphid parthenogenetic lineages from around the world were analysed with six microsatellite loci.

/pdf/tracking-the-global-dispersal-of-a-cosmopolitan-insect-pest-20spzyxvic.pdf

G. Malloch

Papers

Genomic resources for Myzus persicae : EST sequencing, SNP identification, and microarray design

Ribosomal and Mitochondrial DNA Analyses of Xiphinema americanum-Group Populations

Analysis of clonal diversity of the peach-potato aphid, Myzus persicae (Sulzer), in Scotland, UK and evidence for the existence of a predominant clone.

Micro-evolutionary change in relation to insecticide resistance in the peach–potato aphid, Myzus persicae

Tracking the global dispersal of a cosmopolitan insect pest, the peach potato aphid