22 results on '"KREITER S"'
Search Results
2. Colonization of vineyards by phytoseiid mites: their dispersal patterns in the plot and their fate
- Author
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Tixier, M.-S., Kreiter, S., and Auger, P.
- Published
- 2000
- Full Text
- View/download PDF
Catalog
3. Molecular approach in spider mites (Acari: Tetranychidae): Preliminary data on ribosomal DNA sequences
- Author
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Navajas, M., Cotton, D., Kreiter, S., and Gutierrez, J.
- Published
- 1992
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4. Hypersensitive reaction ofSolanum dulcamara to the gall miteAceria cladophthirus causes an increased susceptibility toTetranychus urticae
- Author
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Westphal, E., Perrot-Minnot, M. J., Kreiter, S., and Gutierrez, J.
- Published
- 1992
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- View/download PDF
5. Phytoseiidae (Acari: Mesostigmata) on plants of the family Solanaceae: results of a survey in the south of France and a review of world biodiversity.
- Author
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Tixier MS, Douin M, and Kreiter S
- Subjects
- Animals, Biodiversity, France, Pest Control, Biological, Predatory Behavior, Surveys and Questionnaires, Solanum lycopersicum, Mites
- Abstract
Species of the family Phytoseiidae are predators of pest mites and small insects. Their biodiversity is not equally known according to regions and supporting plants. This paper focuses on Phytoseiidae species on plants of the family Solanaceae. The Solanaceae contain many cultivated plants, for example tomato on which leaf characteristics hinder Phytoseiidae settlement and dispersal. This study presents (i) results of surveys carried out on Solanaceae in the south of France, and (ii) Phytoseiidae biodiversity on Solanaceae worldwide. Eleven species were retrieved on 20 solanaceous plants in the south of France with four main species: Euseius gallicus, Euseius stipulatus, Phytoseiulus persimilis and Typhlodromus (Anthoseius) recki. The global analysis suggests that much more species might be found enhancing sampling efforts, whatever the biogeographic region considered. Five Phytoseiidae genera concentrate the highest number of reports and species [Amblyseius, Neoseiulus, Euseius, Phytoseius and Typhlodromus (Anthoseius)]. These genera are not evolutionarily related; adaptation on Solanaceae seems to be recent, except in the Neotropical region. The latter region represents the highest number of reports, species and Solanaceae plants sampled, probably as the centre of origin of this plant family. Occurrence probabilities in biogeographic regions and plant genera are provided as a baseline for searching for new predators adapted to Solanaceae. more...
- Published
- 2020
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6. Is Neoseiulus wearnei the Neoseiulus californicus of Australia?
- Author
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Tixier MS, Otto J, Kreiter S, Dos Santos V, and Beard J
- Subjects
- Animals, Australia, Female, Male, Mites anatomy & histology, Mites genetics, Mites classification
- Abstract
Species of the family Phytoseiidae are known as predatory mites, some of them being used in crops to control mite pests, all around the world. Neoseiulus (=Cydnodromus) californicus is among the most commonly used Phytoseiidae species in biological control programs, especially in vineyards, orchards and vegetable fields. This species is distributed world-wide but has never been reported from Australia. On the other hand, specimens morphologically close to N. californicus have been assigned to a species called Neoseiulus wearnei, only reported from Australia. Investigations based on morphological and molecular comparisons were carried out to investigate whether these two taxa are conspecific. Morphological analyses showed no significant difference between specimens identified as N. wearnei and N. californicus. Similarly, genetic distances between these taxa were null, showing that all these specimens belong to the same species. Although it is not yet possible to conclude that all the specimens identified as N. wearnei are N. californicus, we can conclude that N. californicus is present in Australia. The information about the biology of N. californicus can thus now be applied to the Australian population of this species for biological control purposes. more...
- Published
- 2014
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7. Different feeding behaviours in a single predatory mite species. 2. Responses of two populations of Phytoseiulus longipes (Acari: Phytoseiidae) to various prey species, prey stages and plant substrates.
- Author
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Ferrero M, Tixier MS, and Kreiter S
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- Animals, Choice Behavior, Female, Male, Food Chain, Food Preferences, Solanum lycopersicum, Phaseolus, Predatory Behavior, Tetranychidae growth & development
- Abstract
Tritrophic studies involving several populations of the predatory mite Phytoseiulus longipes showed distinct life history traits depending on the prey offered and/or the plant substrate. In order to better understand the biology of this predator, the response to several combinations of prey species (Tetranychus evansi and Tetranychus urticae), prey stages (eggs and mobile stages) and plant substrates (bean and tomato leaf discs) has been assessed for two populations of P. longipes. Unlike what was found for life history traits, both populations displayed similar behaviour: they went and stayed more on tomato than on bean, they preferred T. urticae over T. evansi and mobile stages over eggs. Combining the previous life history data with the present results suggests that P. longipes may display host-plant mediated specialization on a prey species, T. evansi. Possible underlying mechanisms are discussed, as well as directions for future work. more...
- Published
- 2014
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8. Different feeding behaviors in a single predatory mite species. 1. Comparative life histories of three populations of Phytoseiulus longipes (Acari: Phytoseiidae) depending on prey species and plant substrate.
- Author
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Ferrero M, Tixier MS, and Kreiter S
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- Animals, Female, Fertility, Longevity, Male, Food Chain, Solanum lycopersicum, Phaseolus, Predatory Behavior, Tetranychidae growth & development
- Abstract
The spider mites Tetranychus evansi and T. urticae are key pests of tomato crops, for which no sustainable practical control strategy is available yet. A Brazilian (B) and an Argentinean (A) population of a phytoseiid predatory mite species, Phytoseiulus longipes, are able to develop and reproduce on T. evansi on tomato, whereas a Chilean (C) population is not. In order to better characterize the two distinct feeding behaviours of these three populations, life table data were assessed when the predator was offered T. evansi or T. urticae as prey on bean or tomato leaves. No effect of the prey offered nor the plant substrate was demonstrated on development durations of the three populations. However, immature mortality was low for the Argentinean and the Brazilian populations whatever the prey or plant substrate, whereas 89 % of P. longipes from Chile died before reaching adulthood when fed T. evansi on tomato. No difference in effect on female longevity was detected among the three populations. Finally, the demographic parameters of all populations were lower in presence of tomato compared to beans. Possible explanations for these results are discussed. more...
- Published
- 2014
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9. Obtaining molecular data for all life stages of Typhlodromus (Typhlodromus) exhilaratus (Mesostigmata: Phytoseiidae): consequences for species identification.
- Author
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Okassa M, Kreiter S, and Tixier MS
- Subjects
- Animals, Female, Male, Mites classification, DNA, Mitochondrial genetics, Life Cycle Stages genetics, Mites genetics, Mites growth & development
- Abstract
Several species of the family Phytoseiidae are known to control mite pests in many crops worldwide. However, biological control success greatly depends on the accurate identification of these predatory mites. Species diagnostics is essentially based on the morphological characters of females. Thus, when only immature stages and/or males are collected, their identification is poorly supported. Molecular tools could be of great help to overcome these difficulties, as molecular sequences are assumed to be identical for the life stage considered. However, one of the essential points is to extract a sufficient DNA amount from a single specimen of immature stages (eggs, protonymphs, deutonymphs) and males (less than 300 μm in length) to amplify and sequence DNA. The markers used were two mitochondrial DNA fragments (12S rRNA and Cytb mtDNA) and the species studied were Typhlodromus (Typhlodromus) exhilaratus and T. (T.) phialatus, two cryptic species, reported to control mite pests in crops of southern Europe and commonly found on the same plants. Despite a low quantity of DNA extracted, particularly for the egg, larva and protonymph stages, DNA was amplified and sequences were obtained from all the life stages considered with the two mtDNA fragments. Sequences from all the developmental stages of T. (T.) exhilaratus were identical and well differentiated from those of its sister-species. However, contaminations were observed especially for eggs and DNA amplified with the Cytb mt marker. Utility of the present results are discussed and protocol improvements are proposed. more...
- Published
- 2012
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10. Agroforestry management and phytoseiid communities in vineyards in the South of France.
- Author
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Liguori M, Tixier MS, Hernandes AF, Douin M, and Kreiter S
- Subjects
- Agriculture, Animals, Forestry, France, Pest Control, Biological, Population Density, Biodiversity, Mites, Pinus, Sorbus, Vitis parasitology
- Abstract
This study deals with the long-term effect of agroforestry management (trees within vine crops) on communities of phytoseiid mites. Several plots were considered: vineyards co-planted with Sorbus domestica or Pinus pinea, monocultures of vines and monocultures of S. domestica or P. pinea. All vine plots included two vine cultivars, Syrah and Grenache. Phytoseiid mites have been surveyed in these plots during several years within the previous 10 years. In 2010, samplings were again carried out in these same plots, from May to September, twice a month. Significantly higher densities of Phytoseiidae were observed on the cultivar Syrah (0.85 phytoseiids per leaf) than on Grenache (0.26 phytoseiids per leaf). Furthermore, significantly higher phytoseiid mite densities were observed in the monocultural grapevine plot than in the two co-planted ones. The main species found was Typhlodromus (Typhlodromus) exhilaratus in all vine plots considered. However, Kampimodromus aberrans was observed in the grapevine plots co-planted with the two trees, but never in the monocultural vine plot. Surprisingly, this phytoseiid species was not found on the co-planted trees, nor in the neighbouring uncultivated vegetation. Several hypotheses are discussed to explain such an unexpected distribution. Furthermore, contrary to what has been observed previously, agroforestry management did not seem to favour phytoseiid mite development, especially on the Grenache cultivar. Again, some hypotheses are developed to explain such observations and density modifications. more...
- Published
- 2011
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11. Influence of ground cover management on diversity and density of phytoseiid mites (Acari: Phytoseiidae) in Guadeloupean citrus orchards.
- Author
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Mailloux J, Le Bellec F, Kreiter S, Tixier MS, and Dubois P
- Subjects
- Animals, Biodiversity, Plants, Population Density, Rain, Temperature, Citrus, Mites physiology, Pest Control, Biological methods
- Abstract
The abundance and diversity of phytoseiid mites in the vegetal ground cover of a citrus orchard were surveyed by monthly samplings from October 2008 to July 2009. Six different vegetal cover management methods were studied: herbicide application without mowing (Gly), mowing without herbicide application (PV), mowing with herbicide application (AV), late mowing without herbicide application (LMV), cover crop (Neonotonia wightii, Fabaceae) without herbicide application (PNeo) and cover crop with herbicide application (ANeo). Eleven species were present in the ground cover, with Phytoseius rex and Proprioseiopsis mexicanus as major species. Species richness and densities (1.5 ± 4.5) in the Gly treatment were very low, except for one sample 4 months after herbicide treatment. The AV and PV treatments showed poor diversity and very low mite densities (1.2 ± 2.6 and 1.4 ± 1.5, respectively). The LMV treatment showed the highest diversity and high density of phytoseiid mites (6.9 ± 8.8). The ANeo and PNeo treatments also showed generally high diversity, but with variations in time and exhibited the highest density of phytoseiid mites (13.5 ± 12.7 and 13.4 ± 9.1, respectively). Neonotonia wightii as the cover crop seems to act as a reservoir of phytoseiid mites, sustaining abundant and diverse populations all year round. Some naturally occurring plant species such as Achyranthes aspera, Amaranthus dubius and Eleutheranthera ruderalis could also constitute favourable host plants for Phytoseiidae. Results are discussed in relation to the potential of collected phytoseiid species as candidates for biological control of phytophagous mites on Guadeloupean citrus orchards. more...
- Published
- 2010
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12. Morphological and molecular diagnostics of Phytoseiulus persimilis and Phytoseiulus macropilis (Acari: Phytoseiidae).
- Author
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Okassa M, Tixier MS, and Kreiter S
- Subjects
- Animals, Cytochromes b chemistry, DNA, Mitochondrial chemistry, Female, Mites classification, Mites genetics, Molecular Sequence Data, Pest Control, Biological, RNA, Ribosomal chemistry, Species Specificity, Mites anatomy & histology
- Abstract
This study focuses on the diagnostics of two natural enemy species, belonging to the genus Phytoseiulus in the family Phytoseiidae (sub-family Amblyseiinae): P. macropilis and P. persimilis. These two species are of primary importance in biological control all over the world. However, they are morphologically very similar and specific diagnostics is difficult. This study utilizes mitochondrial molecular markers (12S rRNA and Cytb mtDNA) to differentiate these two species. Morphological analyses showed significant differences between P. persimilis and P. macropilis for 17 morphological characters of the 32 considered. However, despite these significant differences, the ranges of all characters overlap. Only the serration of the macroseta on the basitarsus (StIV) allows the differentiation between P. persimilis and P. macropilis. Despite these small morphological differences, molecular results, for both mitochondrial DNA fragments considered (rRNA and Cytb mtDNA), showed a clear delineation between the specimens of P. macropilis and P. persimilis. This study emphasizes (i) that only one morphological character (serration of the seta StIV) clearly separates these two species, and (ii) the usefulness of an automatical molecular and simple diagnostic tool for accurate differentiation of the two species and ensure the morphological diagnostics. Further studies are proposed, including more DNA sequences especially for P. macropilis. more...
- Published
- 2010
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13. Cannibalism and intraguild predation in Typhlodromus exhilaratus and T. phialatus (Acari: Phytoseiidae) under laboratory conditions.
- Author
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Meszaros A, Tixier MS, Cheval B, Barbar Z, and Kreiter S
- Subjects
- Animals, Female, Laboratories, Larva, Nymph, Cannibalism, Mites physiology, Predatory Behavior physiology
- Abstract
Two species of Phytoseiidae are found in the same agroecosystem: Typhlodromus exhilaratus prevails in vine plots, while T. phialatus prevails in uncultivated surrounding areas. The objective of the present paper was to investigate whether the poor settlement of T. phialatus in vine plots can be explained by intraguild predation of these two species and/or cannibalism. Predatory abilities of the females on larvae and protonymphs were studied under laboratory conditions. A first experiment was conducted with only conspecific or heterospecific phytoseiid prey, in a second experiment Tetranychus urticae eggs were added to the phytoseiid prey. Oviposition, prey consumption, and escape rates of females were recorded. Oviposition and intraguild predation rates were higher for T. exhilaratus than for T. phialatus. Typhlodromus exhilaratus consumed fewer conspecifics than heterospecific phytoseiids, and oviposited when feeding on both diets. Typhlodromus phialatus consumed equal amounts of con- and heterospecifics. Although these two generalist predators belong to the type III defined by McMurtry and Croft (Annual Review of Entomology 42:291-321, 1997), our results suggest that they have different predation behaviour. However, because these results were obtained in experiments where no choice was given between the two phytoseiid species, they are difficult to link to previous studies conducted on the intraguild predation of the Phytoseiidae. The greater voracity and prolificacy of T. exhilaratus could partially explain the poor settlement of T. phialatus in vineyards and the predominance of T. exhilaratus. However, a full understanding of this phenomenon will require the study of other factors, such as susceptibility to pesticides and micro-climatic conditions, as well as the ability to cope with different food sources and host plants. more...
- Published
- 2007
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14. Search for effective natural enemies of Tetranychus evansi (Acari: Tetranychidae) in northwest Argentina.
- Author
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Furtado IP, Toledo S, de Moraes GJ, Kreiter S, and Knapp M
- Subjects
- Animals, Argentina, Female, Male, Mites classification, Predatory Behavior, Food Chain, Solanaceae parasitology, Tetranychidae classification
- Abstract
The mite Tetranychus evansi Baker & Pritchard (Tetranychidae) probably originated in South America. Because of its importance as a tomato pest in Africa, an extensive project has been conducted to detect potentially effective natural enemies in South America for the classical biological control of the pest in Africa. A search for the natural enemies of T. evansi was conducted in the Province of Tucumán, northwestern Argentina, in December 2004, and this report describes the results. One hundred predatory mites of the family Phytoseiidae referring to 11 species were collected on 11 examined species of solanaceous plants. The most abundant phytoseiid species collected were Neoseiulus californicus (McGregor) and Euseius concordis (Chant). Adults and immatures of those species, as well as of Neoseiulus idaeus Denmark & Muma, Phytoseiulus fragariae Denmark & Schicha and Proprioseiopsis cannaensis (Muma) were found in association with T. evansi, suggesting that they were developing on the pest. However, because of the possible biological differences between populations of a given species, biological studies evaluating T. evansi as a prey for those predators seem desirable. more...
- Published
- 2007
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15. Life tables of the predatory mite Phytoseiulus longipes feeding on Tetranychus evansi at four temperatures (Acari: Phytoseiidae, Tetranychidae).
- Author
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Ferrero M, de Moraes GJ, Kreiter S, Tixier MS, and Knapp M
- Subjects
- Animals, Life Cycle Stages, Life Tables, Reproduction, Temperature, Mites physiology, Predatory Behavior physiology
- Abstract
The tomato red spider mite, Tetranychus evansi, is reported as a severe pest of tomato and other solanaceous crops from Africa, from Atlantic and Mediterranean Islands, and more recently from the south of Europe (Portugal, Spain and France). A population of the predaceous mite Phytoseiulus longipes has been recently found in Brazil in association with T. evansi. The objective of this paper was to assess the development and reproduction abilities of this strain on T. evansi under laboratory conditions at four temperatures: 15, 20, 25 and 30 degrees C. The duration of the immature phase ranged from 3.1 to 15.4 days, at 30 and 15 degrees C, respectively. Global immature lower thermal threshold was 12.0 degrees C. Immature survival was high at all temperatures tested (minimum of 88% at 30 degrees C). The intrinsic rate of increase (r (m)) of P. longipes ranged from 0.091 to 0.416 female/female/day, at 15 and 30 degrees C, respectively. P. longipes would be able to develop at a wide range of temperatures feeding on T. evansi and has the potential to control T. evansi populations. more...
- Published
- 2007
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16. Assessment of pesticide susceptibility for Typhlodromus exhilaratus and Typhlodromus phialatus strains (Acari: Phytoseiidae) from vineyards in the south of France.
- Author
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Barbar Z, Tixier MS, and Kreiter S
- Subjects
- Animals, Chlorpyrifos, Female, France, Male, Maneb, Morpholines, Organothiophosphorus Compounds, Zineb, Fungicides, Industrial, Insecticides, Mites growth & development, Vitis parasitology
- Abstract
Two species of Phytoseiidae predominated in and around vineyards in an experimental site in the south of France: Typhlodromus exhilaratus is the dominant species on grapes, whereas T. phialatus occurs in the uncultivated areas surrounding these crops. To help understand their distribution, this study aims to determine their susceptibility to a fungicide (dimethomorph + mancozeb) and an insecticide (chlorpyriphos-ethyl), which have been widely used at the experimental site for at least four years. The hypothesis tested is that the effects of these two pesticides differ between T. exhilaratus and T. phialatus. Two populations of T. exhilaratus, one collected on a vine crop where the two pesticides were applied and the other in an unsprayed orchard of Sorbus domestica, and one population of T. phialatus collected on Viburnum tinus from uncultivated areas adjacent to the vine crop, were tested under laboratory conditions. The fungicide seems to affect the females of T. phialatus more than those of T. exhilaratus from vine. However, at the recommended field concentration the female mortality rates of the three strains were low and female fecundities were not significantly different. Conversely, mortality rates were very high for the three strains at the recommended field concentration of chlorpyrifos-ethyl. The strain of T. exhilaratus from vine seems to be more tolerant and 20% of females survived the recommended field rate. This suggests better survival after insecticide application than females of T. phialatus (100% mortality at a lower concentration than the recommended rate). As extrapolation of laboratory results to the field is often irrelevant, these differences could be just one of several factors affecting the spatial segregation of the two species in the agrosystem considered. Possible explanations other than pesticides for the poor settlement of T. phialatus in vine plots are discussed. more...
- Published
- 2007
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17. Search for effective natural enemies of Tetranychus evansi in south and southeast Brazil.
- Author
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Furtado IP, de Moraes GJ, Kreiter S, and Knapp M
- Subjects
- Animals, Brazil, Seasons, Tetranychidae classification, Mite Infestations prevention & control, Pest Control, Biological methods, Plant Diseases parasitology, Solanaceae, Tetranychidae growth & development
- Abstract
Tetranychus evansi Baker & Pritchard is an important pest of Solanaceae in several countries. Introduced accidentally to Africa, it presently occurs in many countries of that continent. In some of them, it is considered a key pest. The suspected area of origin of this mite is South America. The objective of the present study was to identify phytoseiid mites on solanaceous plants in association with T. evansi in south and southeast Brazil for introduction in the African continent for use in a classic biological control program. Almost 1,400 predatory mites of the family Phytoseiidae were collected, on 22 solanaceous species. The Amblyseiinae were the most diverse group in this study. Twenty-three of the species found belong to this subfamily, while only three belong to the Typhlodrominae and two to the Phytoseiinae. The most abundant and most frequent phytoseiid species were Phytoseius guianensis De Leon and Galendromus annectens (De Leon) of the Phytoseiinae and Typhlodrominae, respectively. The most frequent and abundant species of Amblyseiinae was Neoseiulus tunus (De Leon). Phytoseius guianensis and N. tunus were never found in association with T. evansi and G. annectens was found only once in association with it. Two factors suggested Phytoseiulus longipes Evans as the most promising predator found in this study. It could walk very well on tomato leaves infested by T. evansi, without being hampered by the profuse webbing produced by the prey and by the trichomes. In addition, several specimens of both sexes including eggs and nymphs of the predator were found associated with T. evansi on three different plant species and in two different periods of the year, when T. evansi was the only arthropod present on the leaves. more...
- Published
- 2006
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18. Effects of agroforestry on phytoseiid mite communities (Acari: Phytoseiidae) in vineyards in the South of France.
- Author
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Barbar Z, Tixier MS, Cheval B, and Kreiter S
- Subjects
- Agriculture methods, Animals, Forestry methods, France epidemiology, Mite Infestations epidemiology, Mites growth & development, Pinus, Plant Diseases parasitology, Sorbus, Vitis
- Abstract
The abundance and diversity of phytoseiid mites were surveyed from April to September 2003 to 2005 in vineyards (Grenache and Syrah cultivars) co-planted with rows of Sorbus domestica or Pinus pinea and in monoculture plots of grapes in the South of France. Densities of phytoseiid mites were different on the two tree species, with P. pinea a more suitable host than S. domestica. Typhlodromus (Typhlodromus) exhilaratus was the dominant species occurring on grapes and on co-planted rows of S. domestica and P. pinea, whereas T. (T.) phialatus was the most abundant species in monoculture plots of both S. domestica and P. pinea. Factors determining the dominance of T. (T.) phialatus over T. (T.) exhilaratus in monoculture trees are discussed. In this study, agroforestry management did not affect phytoseiid diversity in vineyards, but did affect phytoseiid density, especially in 2005. The results obtained in 2003 and 2004 are not easy to discuss in this regard because of the low densities of mites observed during these 2 years (very dry climatic conditions and pesticide applications). more...
- Published
- 2006
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19. Immigration of phytoseiid mites from surrounding uncultivated areas into a newly planted vineyard.
- Author
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Tixier MS, Kreiter S, Cheval B, Guichou S, Auger P, and Bonafos R
- Subjects
- Animals, France, Population Density, Predatory Behavior, Wind, Mites, Pest Control, Biological methods, Sorbus parasitology, Vitis parasitology
- Abstract
This study reports (1) a faunistic survey of phytoseiid mites observed inside a vine plot and in neighbouring vegetation (other vine plots and uncultivated areas) and (2) dispersal of phytoseiid mites into the plot studied. These data aim to raise some hypotheses concerning natural colonisation of a vineyard by predatory mites. The study was carried out over 3 years (1999, 2000 and 2001) in an experimental plot planted with two cultivars (Grenache and Syrah) and with Sorbus domestica in a framework of agroforestry investigations. Phytoseiid mites were collected in both cultivated and uncultivated areas surrounding the experimental plot, and their dispersal into the plot studied using "aerial" traps. Densities remained quite low compared to previous studies. The main species encountered in the uncultivated areas and in the traps was Typhlodromus phialatus. Despite the low numbers of phytoseiid mites trapped, densities of phytoseiid mites into the vine field increased during 3 years. Typhlodromus phialatus, the species mainly found in the neighbouring uncultivated areas, was rarely found in vineyards. Another morphologically close species was predominant on vines: Typhlodromus exhilaratus. However, Kampimodromus aberrans the main phytoseiid mite species in vineyards of Southern France was not found in the present survey. Hypotheses for this colonisation process are discussed. more...
- Published
- 2006
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20. A genetic analysis of mancozeb resistance in Typhlodromus pyri (Acari: Phytoseiidae).
- Author
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Auger P, Bonafos R, Kreiter S, and Delorme R
- Subjects
- Animals, Crosses, Genetic, Drug Resistance, Female, Male, Selection, Genetic, Fungicides, Industrial pharmacology, Maneb pharmacology, Mites drug effects, Mites genetics, Zineb pharmacology
- Abstract
A field population of Typhlodromus pyri (Acari: Phytoseiidae) tolerant to mancozeb was selected in the laboratory. After 10 mancozeb selections the LC50 value for mancozeb was 73 times higher in the selected-10 strain compared to the standard susceptible strain. A genetic analysis using reciprocal crosses and backcrosses of female F1 progeny found no maternal effect. Resistance in the selected-10 strain was codominant in expression, dominance value was about -0.1. Backcrosses between F1 females and the susceptible strain indicate that the resistance to mancozeb could be principally conferred by a predominant gene, but additional factors would also be involved. more...
- Published
- 2005
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21. Cannibalism and interspecific predation in a phytoseiid predator guild from cassava fields in Africa: evidence from the laboratory.
- Author
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Zannou ID, Hanna R, de Moraes GJ, and Kreiter S
- Subjects
- Animals, Benin, Female, Larva, Malawi, Mite Infestations prevention & control, Mites growth & development, Nymph, Pest Control, Biological, Cannibalism, Manihot, Mites physiology, Plant Diseases parasitology, Predatory Behavior
- Abstract
Interspecific predation and cannibalism are common types of interaction in phytoseiid predator guilds, but the extent and nature of these interactions have not been determined yet in phytoseiid guilds composed of African native and neotropical exotic phytoseiid predators found in cassava habitat in southern Africa. We determined in laboratory experiments the level of cannibalism and interspecific predation among the three phytoseiid mite species Euseius fustis, Iphiseius degenerans, and Typhlodromalus aripo in the absence of food and in the presence of limited or abundant quantities of two food types--Mononychellus tanajoa and maize pollen--commonly found on cassava in Africa. When confined without food, only two T. aripo females laid each two eggs within 5 days, and this species survived longer than I. degenerans and E. fustis. In the presence of con- or hetero-specific larvae or protonymphs, the three species fed more on the former than on the latter, and more on hetero-specifics than on con-specifics. Oviposition rates of the three species did not exceed 0.7 egg/female/day on con- and hetero-specific immatures. Typhlodromalus aripo and E. fustis survived longer on con-specific and hetero-specific larvae and on hetero-specific protonymphs than in the absence of any food, while T. aripo survived longer than the two other species on the same diets. Provision of limited quantity of food decreased interspecific predation rate by I. degenerans and T. aripo, but not by E. fustis, and increased oviposition rate and longevity of all three species. Provision of abundant food, however, eliminated cannibalism by all three species and further reduced interspecific predation rates, but their oviposition and longevity remained relatively unchanged compared with limited food provision. Potential consequences of cannibalism and interspecific predation among phytoseiid mites on cassava for the biological control of M. tanajoa are discussed. more...
- Published
- 2005
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22. Side effects of mancozeb on Typhlodromus pyri (Acari: Phytoseiidae) in vineyards: results of multi-year field trials and a laboratory study.
- Author
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Auger P, Kreiter S, Mattioda H, and Duriatti A
- Subjects
- Animals, Female, Phthalimides, Statistics, Nonparametric, Vitis growth & development, Vitis microbiology, Fungicides, Industrial, Maneb, Mites, Zineb
- Abstract
The side effects of mancozeb on the predatory mite Typhlodromus pyri were studied in 4-year field trials on grapevine and in the laboratory. In the field, the effect of mancozeb varied according to previous mancozeb use. In vineyards where mancozeb had commonly been used over years, this fungicide is generally slightly toxic, in some cases moderately toxic and rarely toxic. In plots were mancozeb has never been used, its effect on T. pyri was more pronounced and varied from moderately toxic to toxic. Despite the toxicity of mancozeb, T. pyri populations have never been eradicated. Laboratory results obtained with the French CEB guideline no. 167 confirmed those of the 4-year field study: mancozeb was significantly more toxic to T. pyri populations collected in plots where it had rarely been used before the field experiment. In plots where mancozeb had been used for a long time, the susceptibility of T. pyri populations to this fungicide was reduced and female survival, fecundity but also viability of female progeny were less affected by mancozeb. Even though toxicity of mancozeb increased in controlled conditions, a significant correlation was established between field and laboratory results. more...
- Published
- 2004
- Full Text
- View/download PDF
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