Climate of origin influences how a herbivorous mite responds to drought-stressed host plants

Drought associated with climate change can stress plants, altering their interactions with phytophagous arthropods. Drought not only impacts cultivated plants but also their parasites, which in some cases are favored by drought. Herbivorous arthropods feeding on drought-stressed plants typically produce bigger offspring and develop faster. However, it is unclear how much responses to drought stress differ among populations of herbivore species. Here, we evaluate variability among populations of a major agricultural pest, the two spotted spider mite, Tetranychus urticae, in response to drought stress. We compare key life history parameters of twelve populations that originate from climates ranging from wet and cool Atlantic locations to medium to dry hot Mediterranean locations. We evaluated how plant drought stress affects four life history traits: development time, fecundity, sex-ratio and emigration rate in an experiment comparing well-watered and drought-stressed bean plants. Mites feeding on drought-stressed plants developed faster and attempted to leave leaves less often, and young females were more fecund. The mites from wet temperate climates exhibited greater plasticity between the two water regimes than mites originating from dryer and hot climates, suggesting that the climate in the area of origin influences mite response to drought

Parasites and invasions: changes in gastrointestinal helminth assemblages in invasive and native rodents in Senegal

Understanding why some exotic species become widespread and abundant in their colonised range is a fundamental issue that still needs to be addressed. Among many hypotheses, newly established host populations may benefit from a parasite loss ("enemy release" hypothesis) through impoverishment of their original parasite communities or reduced infection levels. Moreover, the fitness of competing native hosts may be negatively affected by the acquisition of exotic taxa from invaders ("parasite spillover") and/or by an increased transmission risk of native parasites due to their amplification by invaders ("parasite spillback"). We focused on gastrointestinal helminth communities to determine whether these predictions could explain the ongoing invasion success of the commensal house mouse (Mus musculus domesticus) and black rat (Rattus rattus), as well as the associated decrease in native Mastomys spp., in Senegal. For both invasive species, our results were consistent with the predictions of the enemy release hypothesis. A decrease in overall gastrointestinal helminth prevalence and infracommunity species richness was observed along the invasion gradients as well as lower specific prevalence/abundance (Aspiculuris tetraptera in Mus musculus domesticus, Hymenolepis diminuta in Rattus rattus) on the invasion fronts. Conversely, we did not find strong evidence of GIH spillover or spillback in invasion fronts, where native and invasive rodents co-occurred. Further experimental research is needed to determine whether and how the loss of gastrointestinal helminths and reduced infection levels along invasion routes may result in any advantageous effects on invader fitness and competitive advantage

On a dragonfly collection from Nuku Hiva Island, Marquesas Islands and Paea, Tahiti (French Polynesia) with taxonomic discussion of some Polynesian genera (Insecta: Odonata)

A small collection of Odonata from Nuku Hiva Island, Marquesas Islands is presented. It adds Anax guttatus as a new species to this oceanic group. Hemicordulia sp. nov. is reported, but not described because the same species has been sampled before and is pending a formal description. A short taxonomic discussion on observed morphological similarity of male anal appendages in taxa presently assigned to Amorphostigma, Hivaagrion and Ischnura east of New Caledonia is provided. Important considerations for biogeography of the Pacific Odonata are discussed too

La dispersion passive de champignons prédateurs par les substrats de culture peut-elle favoriser le biocontrôle des nématodes phytoparasites en pépinières d’oliviers ?

International audienceDescription of the subject: In Morocco, expanding agricultural sector under "Morocco Green Plan" will also introduce plant diseases and plant parasitic nematodes (PPN). Soil substrate used in most of the olive nurseries is potentially inhabited by PPN and natural enemies.Objectives: This work assessed the co-occurrence of PPN and nematophagous fungi (NF) in substrates and potential of NF to suppress PPN. Method: The diversity of PPN and NF genera was characterized in 305 substrate samples, isolated from 25 olive nurseries and functional activity (nematicidal and enzymatic) of NF was evaluated.Results: High PPN diversity was detected in the isolated samples and substrates were differentiated by NF activity. Global partition between PPN and NF diversity patterns confirmed prey-predator antagonism. Moreover, PPN-NF patterns depend on the fungal survival (saprophytes vs obligate parasites) and antagonism (predation vs toxicity) processes. However, even the NF strains with maximum fitness (growth, sporulation, enzymatic activity) were not inevitably the most effective against PPN. Consequently, it was hypothesized that predation and competition could be an adaptation process of NF to overcome environmental stress and exploit alternative or supplementary nutrient sources.Conclusions: The use of diverse native NF from cultivated and wild soils offer future prospects for the development of PPN management strategies in olive nurseries.Description du sujet : Au Maroc, le développement d’une agriculture intensive dans le cadre du « Plan Maroc Vert » induira très probablement l’émergence de pathologies végétales, dont des nématoses. Dans le cas de l’olivier, la majorité des pépiniéristes utilisent des substrats constitués de sols d'origine indigène potentiellement contaminés en nématodes phytoparasites (NPP) et en champignons nématophages (CNP). Objectifs : Le but de ce travail était de pouvoir évaluer la co-occurrence des NPP et des CNP dans les substrats ainsi que le potentiel antagoniste des CNP. Méthode : La diversité des genres de NPP et de CNP a été caractérisée dans 305 échantillons de substrats prélevés dans 25 pépinières d'oliviers. L'activité fonctionnelle (nématicide et enzymatique) des CNP a été évaluée.Résultats : Une grande diversité de NPP a été détectée, dont les 10 espèces les plus pathogènes à l’échelle mondiale. Les substrats se sont avérés riches en CNP qui diffèrent par leur activité prédatrice. L’analyse des communautés a révélé une partition nette entre NPP et CNP dans les substrats, confirmant l’antagonisme proie-prédateur. De plus, les patrons de NPP et de CNP dépendent de la stratégie trophique des CNP (saprophytes vs parasites obligatoires) et du mode d’antagonisme (prédation vs toxicité) impliqués. Mais les souches de CNP les plus performantes (croissance, sporulation, activité enzymatique) n'étaient pas forcément les plus efficaces contre les NPP. Par conséquent, la prédation et la compétition pourraient être un processus d'adaptation permettant au CNP de surmonter le stress environnemental et d'exploiter des sources nutritives alternatives ou supplémentaires.Conclusions : L'utilisation des CNP indigènes offre des perspectives pour le développement de stratégies de gestion microbiologique des NPP respectueuses de l’environnement

Diversity of nematophagous fungi in Moroccan olive nurseries: Highlighting prey-predator interactions and efficient strains against root-knot nematodes

International audiencePlant-parasitic nematodes are major pests in agriculture. Microbial antagonists such as nematophagous fungi are of great interest for developing alternative biocontrol strategies to replace nematicide use. This study aims to isolate, identify and assess the diversity and the in vitro predatory activity of nematophagous fungi from various olive nurseries in Morocco. A total of 305 soil samples were collected in 25 nurseries in Moroccan olive-producing areas (Jbala, Guerouane, Haouz and Souss). Seventy-three pure fungal strains from nematophagous fungi were recovered from nursery substrates infested with root-knot nematodes. Diversity indices showed that fungi were more numerous in southern regions, whereas fungal communities were more numerically alike in northern regions, partly depending on the occurrence of root-knot nematodes. One fungal strain, Talaromyces assiutensis, killed all Meloidogyne javanica juveniles during in vitro predation tests. Orbiliaceae (Arthrobotrys spp., Drechslerella brochopaga, Monacrosporium spp.) trapped 50 to 80% of juveniles. Purpureocillium and Trichoderma species killed 30 to 50% of juveniles. The diversity of nematophagous communities could be affected by the north-south climate gradient of Morocco, by their nematode prey expansion, and, to a lesser extent, by the habitat origin of the substrates used. Talaromyces assiutensis was the most efficient nematophagous species against M. javanica. The use of native nematophagous fungi is a promising alternative strategy for nematode control in olive nurseries and to prevent nematode introduction into olive orchards

Native and Invasive Small Mammals in Urban Habitats along the Commercial Axis Connecting Benin and Niger, West Africa

International audienceBased on compiled small mammal trapping data collected over 12 years from Benin and Niger (3701 individual records from 66 sampling sites), located in mainland Africa, we here describe the small mammal community assemblage in urban habitats along the commercial axis connecting the two countries, from the seaport of Cotonou to the Sahelian hinterland, with a particular focus on invasive species. In doing so, we document extant species distributions, which highlight the risks of continuing the range expansion of three synanthropic invasive rodent species, namely black rats (Rattus rattus), brown rats (R. norvegicus), and house mice (Mus musculus). Using various diversity estimates and community ecology approaches, we detect a latitudinal gradient of species richness that significantly decreased Northward. We show that shrews (Crocidura) represent a very important component of micro-mammal fauna in West African towns and villages, especially at lower latitudes. We also demonstrate that invasive and native synanthropic rodents do not distribute randomly in West Africa, which suggests that invasive species dynamics and history differ markedly, and that they involve gradual, as well as human-mediated, long distance dispersal. Patterns of segregation are also observed between native Mastomys natalensis and invasive rats R. rattus and R. norvegicus, suggesting potential native-to-invasive species turn over. Consequences of such processes, especially in terms of public health, are discussed

Parasites and invasions: changes in gastrointestinal helminth assemblages in invasive and native rodents in Senegal

International audienceUnderstanding why some exotic species become widespread and abundant in their colonised range is a fundamental issue that still needs to be addressed. Among many hypotheses, newly established host populations may benefit from a parasite loss (''enemy release " hypothesis) through impoverishment of their original parasite communities or reduced infection levels. Moreover, the fitness of competing native hosts may be negatively affected by the acquisition of exotic taxa from invaders (''parasite spillover ") and/or by an increased transmission risk of native parasites due to their amplification by invaders (''parasite spill-back "). We focused on gastrointestinal helminth communities to determine whether these predictions could explain the ongoing invasion success of the commensal house mouse (Mus musculus domesticus) and black rat (Rattus rattus), as well as the associated decrease in native Mastomys spp., in Senegal. For both invasive species, our results were consistent with the predictions of the enemy release hypothesis. A decrease in overall gastrointestinal helminth prevalence and infracommunity species richness was observed along the invasion gradients as well as lower specific prevalence/abundance (Aspiculuris tetra-ptera in Mus musculus domesticus, Hymenolepis diminuta in Rattus rattus) on the invasion fronts. Conversely, we did not find strong evidence of GIH spillover or spillback in invasion fronts, where native and invasive rodents co-occurred. Further experimental research is needed to determine whether and how the loss of gastrointestinal helminths and reduced infection levels along invasion routes may result in any advantageous effects on invader fitness and competitive advantage.

Nematodes associated with saffron II: Bioindication for soil health assessment and impact of agricultural practices

International audienceHighlights: • High diversity of nematodes communities is detected in the Moroccan saffron field. • Saffron soils health are degraded in Taliouine-Taznakht regions. • Plant parasitic index (PPI) is strongly influenced by the high frequency of Traditional irrigation. • Agricultural practices are significantly impacted (MI) and (SI) indices and saffron nematodes trophic groups.Abstract: Background: Saffron cultivation is vital in the Taliouine-Taznakht regions, but the influence of agricultural practices on soil nematode communities, critical for soil health and plant productivity, is not well understood. This study characterizes nematode communities in saffron fields of the Taliouine-Taznakht regions, assessing the impact of various agricultural practices on these communities, with a focus on their diversity, functional roles, and potential as bio-indicators of soil health. A total of 163 soil samples were collected from saffron fields in Taliouine-Taznakht. Nematode communities were identified, quantified, and their functional diversity analyzed. Principal Component Analysis (PCA) was used to visualize relationships between nematode communities and sampling sites. Co-inertia analysis assessed the impact of agricultural practices on nematode diversity. The nematode communities were diverse and varied across regions. PCA identified unique nematode community compositions in different saffron fields. Omnivorous nematodes were strongly linked with Taouyalte (TA), and herbivorous ones were prevalent at Agadir Melloul (AM) and Sidi Hssaine (SH). Modern crop types, high-frequency irrigation, and alfalfa-barley rotation were positively correlated with predator nematode abundance, potentially controlling plant parasitic nematodes and encouraging nutrient cycling. Conversely, monocropping, traditional irrigation, and long plantation age correlated with reduced structure and maturity indices, suggesting a less stable ecosystem. This study unveils the intricate relationships between nematode communities in Taliouine-Taznakht saffron fields and agricultural practices. Findings indicate that specific practices, such as crop rotation and modern irrigation techniques, can foster beneficial nematode groups that improve soil health and potentially regulate harmful plant parasitic nematodes. This knowledge is crucial for crafting sustainable and effective saffron cultivation strategies

Individual and immune variables of rodents from the black rat invasion route.

This file contains all the individual (sex, body mass, age class), methodological (plate factor, initial hemolysis of the serum) and immune (HA, HL, Hp) variables considered in the statistical analyses carried out on rodents from the black rat invasion route