Abstract: Within the framework of a molecular exploration of target resistance in populations of Myzus persicae on oilseed rapes in France, (1) the S431F mutation (coding gene ace2), although previously reckoned to be rare, revealed to be frequent, (2) M918L (phenotypically characterised) and L932F (both on para) were found for the first time in M. persicae, (3) a linkage was revealed between M918L and S431F. While until recently populations developing on French oilseed rapes were dominated by genotypes possessing pyrethroid target resistance and esterase overproduction, to date a different type of dominating genotype, equipped with carbamate and pyrethroid target resistance, seems to be invading such fields.
Abstract: Among global changes induced by human activities, association of breakdown of geographical barriers and impoverishered biodiversity of agroecosystems may have a strong evolutionary impact on pest species. As a consequence of trade networks’ expansion, secondary contacts between incipient species, if hybrid incompatibility is not yet reached, may result in hybrid swarms, even more when empty niches are available as usual in crop fields and farms. By providing important sources of genetic novelty for organisms to adapt in changing environments, hybridization may be strongly involved in the emergence of invasive populations.
Because national and international trade networks offered multiple hybridization opportunities during the previous and current centuries, population structure of many pest species is expected to be the most intricate and its inference often blurred when using fast-evolving markers. Here we show that mito-nuclear sequence datasets may be the most helpful in disentangling successive layers of admixture in the composition of pest populations. As a model we used D. gallinae s. l., a mesostigmatid mite complex of two species primarily parasitizing birds, namely D. gallinae L1 and D. gallinae s. str. The latter is a pest species, considered invading layer farms in Brazil. The structure of the pest as represented by isolates from both wild and domestic birds, from European (with a focus on France), Australian and Brazilian farms, revealed past hybridization events and very recent contact between deeply divergent lineages. The role of wild birds in the dissemination of mites appears to be null in European and Australian farms, but not in Brazilian ones. In French farms, some recent secondary contact is obviously consecutive to trade flows. Scenarios of populations’ history were established, showing five different combinations of more or less dramatic bottlenecks and founder events, nearly interspecific hybridizations and recent population mixing within D. gallinae s. str.
Abstract: Molecular markers for cladistic analyses may perform differently according to the taxonomic group considered and the historical level under investigation. Here we evaluate the phylogenetic potential of five different markers for resolving evolutionary relationships within the ectoparasitic genus Dermanyssus at the species level, and their ability to address questions about the evolution of specialization. COI provided 9–18% divergence between species (up to 9% within species), 16S rRNA 10–16% (up to 4% within species), ITS1 and 2 2–9% (up to 1% within species) and Tropomyosin intron n 8–20% (up to 6% within species). EF-1a revealed different non-orthologous copies withinindividuals of Dermanyssus and Ornithonyssus. Tropomyosin intron n was shown containing consistent phylogenetic signal at the specific level within Dermanyssus and represents a promising marker for future prospects in phylogenetics of Acari. Phylogenetic analyses revealed that the generalist condition is apomorphic and D. gallinae mightrepresent a complex of hybridized lineages. The split into hirsutus-group and gallinae-group in Dermanyssus does not seem to be appropriate based upon these results and D. longipes appears to be composed of two different entities.
Abstract: parasitism of swifts apus sp. by mites of the genus dermanyssus (Acari: mesostigmata).— in the course of a research program on the mites of the genus Dermanyssus, parasites were collected in 2007 and 2008 on live adults and young as well as on complete (after the young fledged) or partial (unsuccessful or old) unoccupied nests of common swift (Apus apus) in gard (southern France) and Pallid
swift (A. pallidus) in corsica. two mite species were found: Dermanyssus gallinae (on common swift, but sampling could have been too small for Pallid swift) and above all a new species Dermanyssus apodis (on both common and Pallid swifts) which has been described in 2009. the eventual effects of these parasites on their hosts are briefly discussed. [in French]
Abstract: The two hematophagous mite species, the Northern Fowl Mite Ornithonyssus sylviarum (Macronyssidae) and the Chicken Red Mite Dermanyssus gallinae (Dermanyssidae), are considered serious pests in fowl farms in the USA and in Europe respectively. However, neither of them seems to be restricted to either of these two continents according to sparse records in the literature. The aim here was to explore the respective ecological repartitions of these two species in France and to compare them with data from the USA. We thus analyzed hematophagous mesostigmatid mites collected in France in natura, in orchards agroecosystems, in pet bird and fowl farms and compared DNA sequences from some North American and French mites in both species. It is remarkable that O. sylviarum has been recurrently encountered in bird nests from France and yet been absent from French layer farms, whereas it is a serious pest in layer farms in the USA. On the other hand, O. sylviarum has been isolated from ornamental bird farms in France (canary, pheasant). This suggests either a strong impact of different farming practices between continents or a colonization in process in Europe. It remains to be explored whether the opposite applies to D. gallinae in the USA. Lastly, mites belonging to the special lineage D. gallinae L1 have been isolated from North American pigeons providing mt and nDNA sequences very close to French L1 isolates. This confirms the specific status of this cryptic entity.
Abstract: The genus Dermanyssus is currently composed of 24 hematophagous mite species and includes the Poultry Red Mite, Dermanyssus gallinae, a serious pest in poultry houses. Morphologically, Dermanyssus species fall into two groups corresponding to Moss’ gallinae-group and to hirsutus-group + Microdermanyssus. Species of the gallinae-group exhibit high levels of morphological variability, and are nearly impossible to distinguish. Species of the second group display consistent characters and host associations and are easily distinguishable. Species of the gallinae-group tend to be the major problems in poultry houses and it is unknown whether D. gallinae is the only pest, or if there are numerous cryptic species present in the system. Twenty species of Dermanyssus were tested phylogenetically based on 46 morphological characters. A subset of species, mainly of the gallinae-group, represented each by several populations, was sequenced for two mitochondrial and one nuclear gene regions. This allowed testing their specific status and their interrelationships based and on morphological and molecular characters. The molecular data was analysed separately and in combination with morphological characters. As expected, morphology did a poor job resolving relationships. Molecular data proved more informative. The resulting phylogenetic hypotheses brought some information about interrelationships among species of the gallinae-group showing a split into two main clades. The invasion of human managed environments seems to occur only in taxa within one of the two clades. The host spectrum seems to get enlarged in more derived taxa in the same clade. A delineation of six species within the gallinae-group is provided. Additionally, a key for morphological identification of these species is provided. D. gallinae appears to be the only pest in poultry houses, but is composed of several different and more or less strongly isolated lineages. A new species found from the black swift is described.
Notes: Contains the description of Dermanyssus apodis Roy, Dowling, Chauve, Buronfosse 2009, based upon morphological and molecular data.
Abstract: This study evaluates both the frequency and distribution of two insecticide families target resistance (pyrethroids and carbamates) in M. persicae populations sampled from oilseed rape cultures in North-Eastern France. Mace target resistance to carbamates proved to be widespread in all 7 administrative geographical areas analyzed (78% of the aphids). Target resistance to pyrethroids induced by kdr mutation was less frequent (< 25% of the aphids). Other mutations affecting the pyrethroids target were, however, detected. Among them, the M918L super-kdr mutation, which had never before been detected in M. persicae, seems to be linked to a strong resistance to pyrethroids.
Abstract: Myzus persicae is a generalist aphid, which parasitizes a diversity of crop plants. The nearly inverted ratio Mace/kdr (two mutations which are linked with high resistance levels against carbamates and pyrethroïds resp. and were found in most individuals separately), have been evidenced in populations developing on oilseed rape in France between 2001 (Mace <¼) and 2009 (Mace >¾). Does this result from the expansion of one lineage with Mace present and kdr absent which was very scarcely encountered in 2001 at the expense of the others or does it result from the introduction of some new populations on this crop ? This very recently started study aims at, on the longer term, inferring scenarios which may explain so dramatic changes. According to first results, no inversion of population structure is revealed as estimated based on neutral markers, but instead a diversification of major genotypes. Two populations seem to be mixed together within the different 2009-2010 isolates and to be respectively associated with one of the two mutations on target proteins.
Abstract: The Poultry Red Mite Dermanyssus gallinae is a hematophagous mite inducing more or less serious damages in layer farms. Uncommon nidicolous habits of this parasite make it very difficult to be controlled, since it does not stay on host. Its dispersal modes also keep unresolved: Are wild birds responsible for it? What is the role of animal trade? Do infestations of two successive flocks in a single building result from two different introduction events or are they due to the ability of mite populations to endure empty periods and cleaning actions? In order to partly answer these questions, some DNA fragments located on two independent genes (Tropomyosin and Cytochrome oxidase 1) have been sequenced in a variety of isolates. Estimation of nucleotide diversity, F-statistics and a bayesian assignment method have been used to explore the population structure of the Poultry Red Mite, then compared to available ecological and economical information. Main results show that wild birds are not involved in the spread of mites today and the lack of differentiation between populations sampled several hundreds if not thousands kilometres apart seem to stem from trade flows. Lastly, an analysis involving several different isolates from a single farm confirms that mite populations at least in some case may resist to the between-flock cleaning up.
Abstract: The genus Dermanyssus Dugès, 1834 (Mesostigmata: Dermanyssidae) includes hematophagous mites that are
ectoparasites of birds. Over the years, the number of species included varied greatly: 56 or more species have once
been classified in this genus, but after the last review by Moss in 1978 only 18 species remained; presently there are
23. Major changes in genus definition drastically reduced the number of species included, involving not only the establishment
of synonymies, but also many changes in systematic position based on literature data (Roy & Chauve, 2007).
However, in 2007 the species definition is not yet clear. We present an overview of the current systematic position of
all 56 species that were once included in this genus. In addition, we review host specificity and geographic distribution
of Dermanyssus species, and we discuss morphological characters posing problems in species characterization.
Abstract: Micropredator species of Dermanyssus (Moss'gallinae-group), which parasitize birds, represent an interesting model for the study of loose associations. Thus, these unwinged arthropods do not stay on host (blood meal as quick as mosquitoe's), are part of the nest's microecosystem and their hosts are winged. Moreover, micropredator Dermanyssus include at least one species of economic importance in fowl farms, D. gallinae (the Poultry Red Mite), which enables the comparison between species restricted to wild avifauna and synanthropic species.
At the beginning of the study, micropredator species are not clearly delimited. Most of species specific morphological characters are variable within species, in some cases within population, and are overlapping between species. In the aim to investigate the ecological needs for proliferation in D. gallinae and its ways for dispersal, a DNA-based comparative analysis involving this species and its close relatives has been performed. The first section consists of the clearing of the taxonomy and species delineations. In the second section, ecological and intrinsic data (host specificity, flexibility) are compared between species of the gallinae-group.
One species has been described (D. apodis), one lineage within D. gallinae seems to represent a cryptic species and D. longipes currently groups two different entities. Important ecological differences between D. gallinae and other species seem to result not only from human activities, but also from intrinsic characteristics. Currently, the role of trade flows in D. gallinae’s spread in layer farms appears to be essential, at least in France, as opposed to the role of wild birds (nearly nul).
