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Publications (230)
Between 1959 and 1988, three populations of purple-flowered terrestrial orchids attributable to Dacty-lorhiza subgenus Dactylorhiza were discovered in Canada. The populations at Timmins, Ontario, and St John's, New-foundland were strongly marked on both flowers and leaves, in contrast with the anthocyanin-deficient population at Tilt Cove, Newfound...
The intensively studied Eurasian orchid genus Dactylorhiza has become a model system for exploring allopolyploid evolution, yet determining the optimal circumscriptions of, and most appropriate ranks for, its constituent taxa remain highly controversial topics. Here, novel allozyme data and detailed morphometric data for 16 Scottish marsh-orchid po...
The aphid Myzus persicae is a destructive agricultural pest that displays an exceptional ability to develop resistance to both natural and synthetic insecticides. To investigate the evolution of resistance in this species we generated a chromosome-scale genome assembly and living panel of >110 fully sequenced globally sampled clonal lines. Our anal...
In Turkey as elsewhere, control of the greenhouse whitefly, Trialeurodes vaporariorum (Westw.) (Hemiptera: Aleyrodidae), relies extensively on the use of insecticides, which can promote the development of insecticide resistance. In this study, resistance to commonly used pyrethroid and neonicotinoid insecticides was investigated using bioassays and...
Soils and plant root rhizospheres have diverse microorganism profiles. Components of this naturally occurring microbiome, arbuscular mycorrhizal (AM) fungi and plant growth promoting rhizobacteria (PGPR), may be beneficial to plant growth. Supplementary application to host plants of AM fungi and PGPR either as single species or multiple species ino...
Circumscriptions of both the genus Gymnadenia and the 11–27 species that it contains are highly controversial. These Eurasian terrestrial orchids are nectar-rewarding and pollinated primarily by Lepidoptera. Opinions expressed on the number of species occurring in the British Isles range from one to four, though there exists broad agreement that at...
Arbuscular Mycorrhizal (AM) fungi form mutualistic symbiotic relationships with approximately 80% of terrestrial plant species, while producing the glycoprotein glomalin as a structural support molecule along their mycelial network. Glomalin confers two benefits for soils: (1) acting as a carbon and nitrogen storage molecule; (2) the binding of soi...
Arbuscular mycorrhizal (AM) fungi are one of the most common fungal organisms to exist in symbiosis with terrestrial plants,
facilitating the growth and maintenance of arable crops. Wheat has been studied extensively for AM fungal symbiosis using
the carcinogen trypan blue as the identifying stain f or fungal components, namely arbuscles, vesicles...
The digitate-tubered clade (Dactylorhiza s.l. plus Gymnadenia s.l.) within subtribe Orchidinae is an important element of the North-temperate orchid flora and has become a model system for studying the genetic and epigenetic consequences of organism-wide ploidy change. Here, we integrate morphological phylogenetics with Sanger sequencing of nrITS a...
An international team of scientists and veterinarians was assembled in 1999 to develop a monitoring program to determine the susceptibility of cat fleas, Ctenocephalides felis felis (Bouché) (Siphonaptera: Pulicidae), to imidacloprid. Cat flea eggs were collected, shipped to laboratories, and tested for their susceptibility to imidacloprid. Over 3,...
Background:
The R81T mutation conferring target site resistance to neonicotinoid insecticides in Myzus persicae was first detected in France and has since spread across much of southern Europe. In response to recent claims of control failure with neonicotinoids in Tunisia, we have used a molecular assay to investigate the presence and distribution...
Although the majority of taxonomic studies of European orchids treat Pseudorchis as a monotypic genus, some observers have argued that the apparently circumboreal segregate P. straminea should also be treated as a full species. Here, we compare detailed in vivo measurements of 55 plants from nine populations of P. albida in Britain with ten plants...
Background:
Tools with the potential to predict risks of insecticide resistance and aid the evaluation and design of resistance management tactics are of value to all sectors of the pest management community. Here we describe use of a versatile individual-based model of resistance evolution to simulate how strategies employing single and multiple...
As well as arising from single point mutations in binding sites or detoxifying enzymes, it is likely that insecticide resistance mechanisms are frequently controlled by multiple genetic factors, resulting in resistance being inherited as a quantitative trait. However, empirical evidence for this is still rare. Here we analyse the causes of up-regul...
Background:
We used molecular assays to diagnose resistance to pyrethroids and pirimicarb in samples of Myzus persicae from field crops or an insect suction trap in Tunisia. Genotypes for resistance loci were related to ones for polymorphic microsatellite loci in order to investigate breeding systems, patterns of genetic diversity and to inform re...
The susceptibility of 12 field-collected isolates and 4 laboratory strains of cat fleas, Ctenocephalides felis was determined by topical application of some of the insecticides used as on-animal therapies to control them. In the tested field-collected flea isolates the LD50 values for fipronil and imidacloprid ranged from 0.09 to 0.35 ng/flea and 0...
The cat flea, Ctenocephalides felis (Siphonaptera: Pulicidae) is the most important ectoparasite of domestic cats and dogs worldwide. Infestations can lead to skin inflammation and cause flea allergy dermatitis, and fleas are also capable of transmitting several other parasites
and diseases between animals and, indirectly, to humans. Fleas have a h...
The first neonicotinoid insecticide, imidacloprid, was launched in 1991. Today this class of insecticides comprises at least seven major compounds with a market share of more than 25% of total global insecticide sales. Neonicotinoid insecticides are highly selective agonists of insect nicotinic acetylcholine receptors and provide farmers with inval...
Preventing a pest population from damaging an agricultural crop and, at the same time, preventing the development of pesticide resistance is a major challenge in crop protection. Understanding how farming practices and environmental factors interact with pest characteristics to influence the spread of resistance is a difficult and complex task. It...
The grain aphid, Sitobion avenae Fabricius (Hemiptera: Aphididae), is an important pest of cereal crops. Pesticides are the main method for control but carry the risk of selecting for resistance. In response to reports of reduced efficacy of pyrethroid sprays applied to S. avenae, field samples were collected and screened for mutations in the volta...
The peach potato aphid, Myzus persicae is a globally distributed crop pest with a host range of over 400 species including many economically important crop plants. The intensive use of insecticides to control this species over many years has led to populations that are now resistant to several classes of insecticide. Work spanning over 40 years has...
Insecticide-treated nets and indoor residual spray programs for malaria control are entirely dependent on pyrethroid insecticides. The ubiquitous exposure of Anopheles mosquitoes to this chemistry has selected for resistance in a number of populations. This threatens the sustainability of our most effective interventions but no operationally practi...
The monitoring of the susceptibility of fleas to insecticides has typically been conducted by exposing adults on treated surfaces. Other methods such as topical applications of insecticides to adults and larval bioassays on treated rearing media have been developed. Unfortunately, baseline responses of susceptible strains of cat flea, Ctenocephalid...
Widespread use of insecticides to control arthropod pests of agricultural, veterinary, and medical importance imposes selection for resistance to these chemicals. Resistance is an evolutionary adaptation conferred by genes encoding modified receptor proteins or enzymes that detoxify insecticides. Advances in insect biochemistry and genomics are cas...
Background:
Insecticides are important tools for managing damaging insect pests. Compounds that are effective against pests such as the whiteflies Bemisia tabaci and Trialeurodes vaporariorum, which show resistance to a range of insecticidal modes of action (MOA), have particular value as components of resistance management programmes. The sulfoxi...
In 2001, an international surveillance initiative was established, utilising a validated larval development inhibition assay to track the susceptibility of cat flea isolates to imidacloprid. In 2009, an Australian node was incorporated into the programme, joining laboratories in the United States and Europe. Field isolates of Ctenocephalides felis...
Resistance levels in whitefly, Bemisia tabaci (Gennadius) collections from cotton and sunflower (up to four districts) for five neonicotinoids and two insect growth regulators (IGRs) were investigated for two consecutive years. Based on the LC50(s), all collections showed slight to moderate levels of resistance for the tested insecticides compared...
Resistance to the organophosphate chlorpyrifos ethyl was investigated in greenhouse populations of Trialeurodes vaporariorum from Turkey using both bioassay and biochemical studies. These populations were collected from Antalya, Izmir, and Mersin. LC50 values to chlorpyrifos ethyl were determined for all populations using leaf dip bioassay. Resista...
Trialeurodes vaporariorum Westwood is an important pest of protected crops in temperate regions of the world. Resistance to pyrethroid insecticides is long established in this species, but the molecular basis of the mechanism(s) responsible has not previously been disclosed.
Mortality rates of three European strains of T. vaporariorum to the pyreth...
Spasmodic progress in understanding the morphology of European allotetraploid marsh-orchids of the genus Dactylorhiza achieved in the second half of the twentieth century has in the twenty-first century been largely superseded by rapid progress in the molecular systematics of the group. However, a grand synthesis is still needed to integrate the re...
Parthenogenetic clones of the green peach aphid, Myzus persicae (Sulzer), and the cotton aphid, Aphis gossypii Glover, were tested with the anthranilic diamide insecticide cyantraniliprole (i.e. DuPont(™) Cyazypyr(™) ) in systemic-uptake bioassays to investigate potential for cross-resistance conferred by mechanisms of insecticide resistance to org...
Spiromesifen is a novel insecticide and is classed as a tetronic acid derivative. It targets the insects' acetyl-coenzyme A carboxylase (ACCase) enzyme, causing a reduction in lipid biosynthesis. At the time of this publication, there are no reports of resistance to this class of insecticides in insects although resistance has been observed in seve...
The juvenile hormone mimic, pyriproxyfen is a suppressor of insect embryogenesis and development, and is effective at controlling pests such as the greenhouse whitefly Trialeurodes vaporariorum (Westwood) which are resistant to other chemical classes of insecticides. Although there are reports of insects evolving resistance to pyriproxyfen, the und...
CYP4G61
nucleotide sequences for the strains TV1 (assembled from 454 reads for this strain) and TV8pyrsel (identified by direct cDNA sequencing of this strain).
(TXT)
Probe IDs, corresponding contigs and closest BLAST hits in the NCBI nr database for each unique contig. (Note that only the contigs that returned a BLAST result are shown).
(XLS)
Volcano plot for the Trialeurodes vaporariorum microarray. Genes meeting a p value cut-off of 0.01 and showing a transcription ratio >2 fold in either direction were considered to be differentially transcribed between the two strains and here are represented by dark dots.
(TIF)
Amino acid alignment of two translated contigs (4648 and 21292) that they are coding for the full length CYP4G61 gene. Silent SNPs are marked in yellow coloured boxes and amino acid substitutions in green boxes.
(TIF)
Sequences of primers used in this study. Primer sequences are listed along with the purpose for which they were designed.
(XLS)
Genes identified by microarray analysis as significantly differentially transcribed between the pyriproxyfen resistant strain TV8pyrsel and the susceptible TV1. Here, the full list of these genes, along with probe name, p-value, fold-change and log2 fold-change, as well as a description based on the closest BLAST hit are detailed.
(XLS)
Four strains of the Q biotype and one of the B biotype of the whitefly Bemisia tabaci collected from China were characterised for resistance to four neonicotinoid insecticides and pymetrozine. Q biotype strains showed moderate to strong resistance to imidacloprid, thiamethoxam and acetamiprid, but little or no cross-resistance to dinotefuron. Resis...
a b s t r a c t The whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae), is an invasive insect pest of agriculture and horti-culture worldwide. The neonicotinoid insecticides, which target nicotinic acetylcholine receptors in post-synaptic nerve membranes, play a major role in controlling B. tabaci although the increasing incidence of resistance to t...
ESTs identified by microarray analysis significantly differentially transcribed between the insecticide resistant M. persicae clone FRC and the susceptible clone 4106A. The full list of ESTs along with Log2, calculated fold-change values and a description based on the closest BLAST hit is detailed.
Fold change in expression of CYP6CY3 and additional P450 genes in the M. persicae clones FRC and 5191A (compared to the susceptible reference clone 4106A) as determined by quantitative PCR. For each EST the most similar Acyrthosiphon pisum P450 gene is detailed.
Sequences of primers used in this study. Primer sequences are listed along with the purpose for which they were used.
Selected-Reaction-Monitoring transitions for selected imidacloprid metabolites. Molecular weight, SRM transitions, collision energies and availability of authentic standards are detailed for 11 imidacloprid metabolites.
Myzus persicae is a globally important aphid pest with a history of developing resistance to insecticides. Unusually, neonicotinoids have remained highly effective as control agents despite nearly two decades of steadily increasing use. In this study, a clone of M. persicae collected from southern France was found, for the first time, to exhibit su...
Although on-animal topical treatment with compounds such as imidacloprid has revolutionized the control of the cat flea, Ctenocephalides felis (Bouché) (Siphonaptera: Pulicidae), the development of insecticide resistance is a continuing threat. As part of a highly co-ordinated and unprecedented resistance monitoring programme for C. felis, 1437 fle...
Characteristics of assembled Trialeurodes vaporariorum 454 contigs and BLASTx alignments against Drosophila melanogaster. (A,B) length and coverage of contigs, (C,D) percent identity and deduced amino acid alignment length for all blast hits to D. melanogaster predicted proteins (additional file 1.pdf)
E-value (A) and percentage similarity (B) distributions of the top BLAST hit for each contig of Trialeurodes vaporariorum (additional file 3.tiff)
Names, corresponding contig numbers, amino-acid sequences and Acyrthosiphon pisum or Bemisia tabaci orthologues of contigs that encode detoxifying enzymes (additional file 4.xls)
Top BLAST hits in the NCBI nr database for each unique contig. Note that only the contigs that returned a BLAST result are shown in this file (additional file 2.xls)
Nucleotide sequences of target sites of the most important insecticide classes (additional file 8.txt)
Single nucleotide polymorphisms (SNPs) arising due to nucleotide divergence between the two strains (TV1 and TV6) (additional file 9.xls)
P450s nucleotide sequences (additional file 5.txt)
CCEs nucleotide sequences (additional file 6.txt)
GSTs nucleotide sequences (additional file 7.txt)
The whitefly Trialeurodes vaporariorum is an economically important crop pest in temperate regions that has developed resistance to most classes of insecticides. However, the molecular mechanisms underlying resistance have not been characterised and, to date, progress has been hampered by a lack of nucleotide sequence data for this species. Here, w...
Trialeurodes vaporariorum (Westwood), also known as the greenhouse whitefly, is a serious pest of protected vegetable and ornamental crops in most temperate regions of the world. Neonicotinoid insecticides are used widely to control this species, although resistance has been reported and may be becoming widespread.
Mortality rates of UK and Europea...
Insecticide-resistant clones of the peach-potato aphid, Myzus persicae (Sulzer), have previously been shown to have a reduced response to aphid alarm pheromone compared to susceptible ones. The resulting vulnerability of susceptible and resistant aphids to attack by the primary endoparasitoid, Diaeretiella rapae (McIntosh), was investigated across...
Background:
Although cross-resistance between compounds in the same insecticide group is a frequently observed phenomenon, cross-resistance between groups that differ in structural and functional characteristics can be extremely unpredictable. In the case of controlling the whitefly, Bemisia tabaci Gennadius, neonicotinoids and the pyridine azomet...
The discovery of sulfoxaflor [N-[methyloxido[1-[6-(trifluoromethyl)-3-pyridinyl]ethyl]-λ(4)-sulfanylidene] cyanamide] resulted from an investigation of the sulfoximine functional group as a novel bioactive scaffold for insecticidal activity and a subsequent extensive structure-activity relationship study. Sulfoxaflor, the first product from this ne...
Onion thrips, Thrips tabaci Lindeman, is a prevalent pest of glasshouse and field vegetables, such as leeks and salad onions. Pesticides are the main option for control, but this approach risks the evolution and spread of insecticide resistance. In the light of anecdotal reports in the United Kingdom of poor efficacy of pyrethroids against T. tabac...
Genes identified by microarray analysis significantly differentially transcribed between the insecticide resistant M. persicae clone 5191A and the susceptible clone 4106A. Microarray array analysis identified 273 genes significantly differentially transcribed between the insecticide resistant clone 5191A and the susceptible clone 4106A. The full li...
Sequences of primers used in this study. Primer sequences are listed along with the purpose for which they were used.
(0.03 MB XLS)
An amino acid alignment of Acyrthosiphon pisum CYP6CY3 with five partial EST gene sequences encoding P450s identified by microarray with elevated expression in the insecticide resistant M. persicae clone 5191A.
(0.10 MB DOC)
Effective control of the brown planthopper, Nilaparvata lugens Stål, across rice-growing regions of Asia has been seriously compromised over the last 2 years by the appearance of widespread resistance to the neonicotinoid insecticide, imidacloprid. Sequence analysis of the ligand-binding domain of the nicotinic acetylcholine receptor α1 subunit fro...
The aphid Myzus persicae is a globally significant crop pest that has evolved high levels of resistance to almost all classes of insecticide. To date, the neonicotinoids, an economically important class of insecticides that target nicotinic acetylcholine receptors (nAChRs), have remained an effective control measure; however, recent reports of resi...
Dispersion of invasive biotypes of the tobacco whitefly, Bemisia tabaci, has led to protracted crop protection constraints in numerous countries over recent decades. These polyphagous, highly efficient vectors of plant viruses present an intractable problem as they frequently carry a diverse suite of insecticide resistance mechanisms. In many areas...
The global importance of Bemisia tabaci (Gennadius) offers unique opportunities to examine patterns of infestation among diverse habitats and identify major factors
that determine pest status. Its occurrence on field, vegetable and ornamental crops grown under open or protected conditions
in temperate or tropical environments plays a critical role...
This chapter reviews the origins and mechanisms of resistance, the factors that influence its severity, and the current options for combating its detrimental impact on agricultural productivity and human health. The evolution of insecticide resistance is an obvious constraint on effective pest management, both of agricultural pests and of vectors o...
In the UK, the flowers of fruit-bearing hedgerow plants provide a succession of pollen and nectar for flower-visiting insects for much of the year. The fruits of hedgerow plants are a source of winter food for frugivorous birds on farmland. It is unclear whether recent declines in pollinator populations are likely to threaten fruit-set and hence fo...
Flowers of common ivy (Hedera helix L.) provide late season pollen and nectar for several insect groups, and its fruits are a winter and spring food source for
frugivorous birds. Ivy benefits from insect pollination in order to set fruit, but it is unknown which flower-visiting insects
are the most effective pollinators. Our observations suggest th...
We developed new methods for analyzing inheritance of insecticide resistance in haplodiploid arthropods and applied them to elucidate resistance of the whitefly Bemisia tabaci (Gennadius) to an insect growth regulator, pyriproxyfen. Two invasive biotypes of this devastating crop pest, the B biotype in Arizona and the Q biotype in Israel, have evolv...
Over the last decade, the number of pesticides registered for sale in Europe has reduced by more than 50%, with only about 400 active ingredients remaining on the market. It is predicted that by the end of 2008 only 372 will remain on the market. While the number of active ingredients will have declined by an estimated 61% by the end of the year, i...
Two full-length genes encoding different acetylcholinesterases (AChEs), designated as Ch-ace1 and Ch-ace2, were cloned from strains of the rice stem borer (Chilo suppressalis) susceptible and resistant to the organophosphate insecticide triazophos. Sequence analysis found an amino acid mutation A314S in Ch-ace1 (corresponding to A201 in Torpedo cal...
Neonicotinoid insecticides retain a crucial role within many chemical and integrated control strategies for the tobacco whitefly, Bemisia tabaci Gennadius, in spite of the establishment of potent and widespread resistance in many areas. Metabolic resistance mechanisms mediated by overexpression of P450‐dependent monooxygenases have been implicated...
