Inventaire des moustiques (Diptera : Culicidae) des îles du sud-ouest de l’océan Indien,Madagascar excepté — Une revue critique

Inventory of the mosquitoes (Diptera: Culicidae) of the islands of southwestern Indian Ocean, Madagascar excluded – A Critical Review. The biodiversity of mosquitoes in the islands of southwestern Indian Ocean is the concern of numerous publications. Here, we propose a synthetic inventory and the analysis of the mosquito diversity, based on the available literature. A comprehensive annotated checklist of mosquito species has been recently published on Madagascar; this is the reason why this land is excluded from our work. Studied area encompasses 28 tropical islands in the southern hemisphere: 4 islands in the Comoros archipelago, 5 Scattered Islands (îles Éparses), 5 in Mascarene, 11 in the Seychelles and 3 in the Chagos archipelago. In total, the mosquito list presents 73 valid species, of which 10 are Anophelinae and 63 Culicinae. The number of species that are distributed in these islands only is 19, i.e. 26%, which is a remarkable level for endemism. The richness in mosquito species in these islands is analysed through several aspects including geography, local speciation and natural or human dissemination. This updated inventory increases by 33% the number of known species by regard to the previous inventory published by Julvez & Mouchet in 1994. The historical responsibility of humans in the introduction of new mosquito species in these islands is strongly documented. For instance, the species with the highest distribution among islands are Aedes aegypti, Ae. albopictus and Culex quinquefasciatus. The islands belong to the afrotropical biogeographic area and, logically, the majority (63%) of mosquito species present phylogenetic affinities with continental Africa and/or Madagascar; interestingly, the number of species present in these islands and in Madagascar but absent in continental Africa is higher than the number of species present in these islands and in continental Africa but absent in Madagascar (respectively 12 and 2 species). Thanks to valuable increase in the sampling effort, our knowledge of the culicidian fauna is increasing in these islands that constitute indisputably hotspots of biodiversity.     

The microsporidian pathogen Myrmecomorba nylanderiae: Intracolony transmission and impact upon tawny crazy ant (Nylanderia fulva) colonies

The microsporidian pathogen Myrmecomorba nylanderiae Plowes et al. infects introduced tawny crazy ants (Nylanderia fulva (Mayr)), and constitutes one of the first natural enemies known to attack this invasive ant. We assess how infection is transmitted within colonies and how infection impacts N. fulva colony fragment growth under carbohydrate‐deficient and carbohydrate‐sufficient dietary conditions. Carbohydrate scarcity is a common source of stress for ant colonies. Infected workers efficiently pass infection to developing larvae but all other potential pathways for within colony transmission are rare or non‐viable. For unknown reasons, queens within infected colony fragments are generally uninfected, limiting the role of transovarial transmission in intracolony transmission. In the laboratory, infection by M. nylanderiae primarily impacts the growth of N. fulva colonies by reducing pupal production. Colony growth showed a substantially greater impact under carbohydrate‐deficient conditions implying that the effect of the pathogen may depend on seasonally variable carbohydrate availability. In the colony growth assay, worker mortality did not differ with infection status under either nutrient regime. However, in a longer, direct test of survivorship, infected worker survivorship was significantly lower. Recently, some established N. fulva populations with high prevalence of M. nylanderiae infection have declined precipitously, though it is unknown if M. nylanderiae is a causative agent in these declines. The combination of chronic impacts, presence in North America, and potential association with population declines makes M. nylanderiae a promising prospect for the biological control of N. fulva.     

Cranial morphological scaling and relative prey size limitations for a native predator in an invaded system

Over evolutionary time, predator-prey interactions have shaped and constrained functional and behavioral traits of piscivorous fishes. The endangered Colorado Pikeminnow Ptychocheilus lucius, a large endemic piscivore of the Colorado River Basin, encounters a substantially altered prey base that differs in behaviors and morphologies compared to the historical suite of native prey. To assess physical limitations of Colorado Pikeminnow predation, we conducted a feeding experiment with two species of nonnative prey (spined and despined Channel Catfish Ictalurus punctatus and Red Shiner Cyprinella lutrensis) and quantified scaling of cranial morphology in this predator. In our predation experiments, Colorado Pikeminnow (215–312 mm total length) consumed both spined and despined Channel Catfish as well as Red Shiner but only consumed prey less than 20% of the predator’s total length. Previous feeding trials using smaller Colorado Pikeminnow, with native and nonnative prey species, indicated they consumed prey up to 35% of their total length, suggesting relative prey size limits may decrease as this predator grows. Morphological measurements also suggested relative prey size suitability may decrease as Colorado Pikeminnow become larger, with head depth and width demonstrating isometric scaling at small sizes and shifting to negative allometry as fish get larger. Together, these data suggest an ontogenetic shift in the head morphology of Colorado Pikeminnow may decrease the relative size of prey available to these predators. In severely altered systems, understanding trophic characteristics that limit overall predator resource availability will be critical for conservation of piscivorous fishes.     

A cascade synthesis, in vitro cholinesterases inhibitory activity and docking studies of novel Tacrine-pyranopyrazole derivatives

In this work, we describe the preparation of some new Tacrine analogues modified with a pyranopyrazole moiety. A one-pot multicomponent reaction of 3-methyl-1H-pyrazol-5(4H)-one, aryl(or hetero)aldehydes, malononitrile and cyclohexanone involving a Friedländer condensation led to the title compounds. The synthesized heterocyclic analogues of this molecule were evaluated in vitro for their AChE and BChE inhibitory activities in search for potent cholinesterase enzyme inhibitors. Most of the synthesized compounds displayed remarkable AChE inhibitory activities with IC₅₀ values ranging from 0.044 to 5.80?µM, wherein compounds 5e and 5j were found to be most active inhibitors against AChE with IC₅₀ values of 0.058 and 0.044?µM respectively. Molecular modeling simulation on AChE and BChE receptors, showed good correlation between IC₅₀ values and binding interaction template of the most active inhibitors docked into the active site of their relevant enzymes.     

Development of a UHPLC-FLD method for the analysis of ergot alkaloids and application to different types of cereals from Luxembourg

Ergot alkaloids are toxins produced by some species of fungi in the genus Claviceps, that may infect rye and triticale and, in a minor degree, other types of cereals. In this study, a new UHPLC-FLD method for the quantification of the six major ergot alkaloids as well as their corresponding epimers was developed. The sample preparation was done by a solid-liquid extraction with acetonitrile and clean-up via freeze-out. The method was fully validated and then applied to 39 samples (wheat, rye, triticale, and barley) harvested in Luxembourg in 2016. Samples were sieved (1.9?×?20 mm) prior to analysis in order to remove sclerotia, hosting the alkaloids. However, 23 samples still contained at least one ergot alkaloid >?LOQ and concentrations of the sum of the 6 ergot alkaloids ranged from 0.3 to 2530.1 μg/kg. Interestingly, the highest concentrations were measured in wheat and not in rye or triticale, suggesting that all kinds of cereals should be included in monitoring programs. The outcome of this study allowed giving a first overview of ergot alkaloid concentrations in cereals harvested in Luxembourg, and the measured concentrations were in similar ranges than in other parts of the world (e.g., Canada, France, Germany).     

Agriculture shapes the trophic niche of a bat preying on multiple pest arthropods across Europe: Evidence from DNA metabarcoding

The interaction between agricultural production and wildlife can shape, and even condition, the functioning of both systems. In this study, we i) explored the degree to which a widespread European bat, namely the common bent‐wing bat Miniopterus schreibersii, consumes crop‐damaging insects at a continental scale, and ii) tested whether its dietary niche is shaped by the extension and type of agricultural fields. We employed a dual‐primer DNA metabarcoding approach to characterize arthropod 16S and COI DNA sequences within bat faecal pellets collected across 16 Southern European localities, to first characterize the bat species’ dietary niche, second measure the incidence of agricultural pests across their ranges and third assess whether geographical dietary variation responds to climatic, landscape diversity, agriculture type and vegetation productivity factors. We detected 12 arthropod orders, among which lepidopterans were predominant. We identified >200 species, 44 of which are known to cause agricultural damage. Pest species were detected at all but one sampling site and in 94% of the analysed samples. Furthermore, the dietary diversity of M. schreibersii exhibited a negative linear relation with the area of intensive agricultural fields, thus suggesting crops restrict the dietary niche of bats to prey taxa associated with agricultural production within their foraging range. Overall, our results imply that M. schreibersii might be a valuable asset for biological pest suppression in a variety of agricultural productions and highlight the dynamic interplay between wildlife and agricultural systems.     

Sex‐dependent thermal history influences cold tolerance,longevity and fecundity in false codling moth Thaumatotibia leucotreta (Lepidoptera: Tortricidae)

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A new cell surface proteinase: sequencing and analysis of the prtB gene from Lactobacillus delbruekii subsp. bulgaricus.

Investigation of the chromosomal region downstream of the lacZ gene from Lactobacillus delbrueckii subsp. bulgaricus revealed the presence of a gene (prtB) encoding a proteinase of 1,946 residues with a predicted molecular mass of 212 kDa. The deduced amino acid sequence showed that PrtB proteinase displays significant homology with the N termini and catalytic domains of lactococcal PrtP cell surface proteinases and is probably synthesized as a preproprotein. However, the presence of a cysteine near the histidine of the PrtB active site suggests that PrtB belongs to the subfamily of cysteine subtilisins. The C-terminal region strongly differs from those of PrtP proteinases by having a high lysine content, an imperfect duplication of 41 residues, and a degenerated sequence compared with the consensus sequence for proteins anchoring in the cell walls of gram-positive bacteria. Finally, the product of the truncated prtM-like gene located immediately upstream of the prtB gene seems too short to be involved in the maturation of PrtB.     

Spatial variation in selection in a plant-pollinator system in the wadis of Sinai,Egypt

We studied an insect-plant pollination system in adjacent steep-sided wadis and a connecting plain in the mountains of southern Sinai (Egypt): this environment creates a strongly divided habitat, which may promote the local differentiation of sub-populations. We tested for spatial differences in phenotypic reproductive characters of the only plant flowering abundantly in early spring, Alkanna orientalis (Boraginaceae), and its major pollinator at that time of year, Anthophora pauperata (Apoidea, Anthophoridae). There were significant morphological differences between sub-populations of Alkanna, mainly between plants from the narrower wadis and those on the interconnecting plain. Flowers on the plain were larger, with wider corollas and more nectar standing crop; these plants retained more flowers on the inflorescence, but received many fewer visits to flowers. There was a significant selection gradient between flower size and maternal fitness (seed set) in the plain, but not elsewhere. Natural selection may have increased resources devoted to attracting insect visitors in response to fewer pollinating visits in the plain. Consistent with this explanation, by experimentally manipulating flower number per plant, we showed that within a wadi having more flowers on a plant secured more visits.