Engineered inorganic core/shell nanoparticles

International audienceIt has been for a long time recognized that nanoparticles are of great scientific interest as they are effectively a bridge between bulk materials and atomic structures. At first, size effects occurring in single elements have been studied. More recently, progress in chemical and physical synthesis routes permitted the preparation of more complex structures. Such structures take advantages of new adjustable parameters including stoichiometry, chemical ordering, shape and segregation opening new fields with tailored materials for biology, mechanics, optics magnetism, chemistry catalysis, solar cells and microelectronics. Among them, core/shell structures are a particular class of nanoparticles made with an inorganic core and one or several inorganic shell layer(s). In earlier work, the shell was merely used as a protective coating for the core. More recently, it has been shown that it is possible to tune the physical properties in a larger range than that of each material taken separately. The goal of the present review is to discuss the basic properties of the different types of core/shell nanoparticles including a large variety of heterostructures. We restrict ourselves on all inorganic (on inorganic/inorganic) core/shell structures. In the light of recent developments, the applications of inorganic core/shell particles are found in many fields including biology, chemistry, physics and engineering. In addition to a representative overview of the properties, general concepts based on solid state physics are considered for material selection and for identifying criteria linking the core/shell structure and its resulting properties. Chemical and physical routes for the synthesis and specific methods for the study of core/shell nanoparticle are briefly discussed

Evidence for a cryptic parasitoid species reveals its suitability as a biological control agent.

Uncertainty about the taxonomic status and the specificity of a species commonly prevent its consideration as a candidate for biological control of pest organisms. Here we use a combination of molecular analysis and crossing experiments to gather evidence that the parasitoid wasp Ganaspis brasiliensis, a candidate for biological control of the invasive spotted wing drosophila Drosophila suzukii, is a complex of at least two cryptic species. Complementary experiments demonstrate that individuals from one genetic group readily parasitize several drosophila species regardless of their food source while individuals from the other one are almost exclusively specific to larvae feeding in ripening fruits. Because only D. suzukii attacks ripening fruits in its area of invasion, parasitoids from this second group appear to be well suited as a biological control agent. Our study demonstrates the need for a combination of biosystematics with biological and ecological investigations for the development of safe and efficient biological control programs

Recherche d’espèces du genre Trichogramma sur Cucurbitacées cultivées et plantes associées en Martinique en vue du développement de méthodes de lutte biologique (Hymenoptera, Trichogrammatidae)

Sampling of Trichogramma species on Cucurbitaceae and associated plants in Martinique : a first step towards biological control (Hymenoptera, Trichogrammatidae). Cucurbitaceae represent an important part of the vegetable production in Martinique. One of the main pest on these crops is the melonworm, Diaphana hyalinata. With the final objective of defining sustainable strategies for the management of this pest with low quantities of pesticides, an inventory of the Trichogramma egg parasitoids was conducted in 2014 on the island. This survey was implemented using two methods, the use of sentinel eggs of Ephestia kuehniella and collections of natural egg clutches. Based on molecular information, two species were finally observed, Trichogramma pretiosum Riley, 1879, and T. chilonis Ishii, 1941. Based on this survey, a strain of T. pretiosum was mass-reared using Corcyra cephalonica and used for first promising inundative releases.Les Cucurbitacées représentent une part importante de la production maraîchère de Martinique. Un des principaux ravageurs de ces cultures est la Pyrale des cucurbitacées, Diaphania hyalinata. Avec pour objectif final la définition de stratégies de gestion économe en produits phytosanitaires, un inventaire des parasitoïdes oophages du genre Trichogramma a été réalisé en novembre 2014 sur l’île de la Martinique. Cet échantillonnage a été réalisé selon deux méthodes, l’utilisation d’oeufs-sentinelles d’Ephestia kuehniella et la recherche de pontes naturelles. Au final, deux espèces ont été identifiées sur une base moléculaire, Trichogramma pretiosum Riley, 1879, et T. chilonis Ishii, 1941. Suite à cet échantillonnage, T. pretiosum a été mis en élevage sur un hôte de substitution, Corcyra cephalonica, et utilisé pour des premiers lâchers inondatifs prometteurs.Dumbardon-Martial Thierry, Lucas Pierre-Damien, Warot Sylvie, Ris Nicolas, Groussier Géraldine. Recherche d’espèces du genre Trichogramma sur Cucurbitacées cultivées et plantes associées en Martinique en vue du développement de méthodes de lutte biologique (Hymenoptera, Trichogrammatidae). In: Bulletin de la Société entomologique de France, volume 123 (4),2018. pp. 401-410

First record of Telenomus kolbei (Hymenoptera, Scelionidae) in France, parasitizing the eggs of Nymphalis antiopa and Aglais io (Lepidoptera, Nymphalidae)

Telenomus kolbei is newly reported in France, parasitizing two new host species: Aglais io and Nymphalis antiopa. Oviposition by the parasitoid into eggs of both species was observed. Films were made, to which links are given. DNA sequences were obtained and deposited in Genbank

Investigating Biological Control Agents for Controlling Invasive Populations of the Mealybug Pseudococcus comstocki in France

WOS: 000378865200032PubMed ID: 27362639Pseudococcus comstocki (Hemiptera: Pseudococcidae) is a mealybug species native to Eastern Asia and present as an invasive pest in northern Italy and southern France since the start of the century. It infests apple and pear trees, grapevines and some ornamental trees. Biocontrol programmes against this pest proved successful in central Asia and North America in the second half of the 20th century. In this study, we investigated possible bio-control agents against P. comstocki, with the aim of developing a biocontrol programme in France. We carried out systematic DNA-barcoding at each step in the search for a specialist parasitoid. First we characterised the French target populations of P. comstocki. We then identified the parasitoids attacking P. comstocki in France. Finally, we searched for foreign mealybug populations identified a priori as P. comstocki and surveyed their hymenopteran parasitoids. Three mealybug species (P. comstocki, P. viburni and P. cryptus) were identified during the survey, together with at least 16 different parasitoid taxa. We selected candidate biological control agent populations for use against P. comstocki in France, from the species Allotropa burrelli (Hymenoptera: Platygastridae) and Acerophagus malinus (Hymenoptera: Encyrtidae). The coupling of molecular and morphological characterisation for both pests and natural enemies facilitated the programme development and the rejection of unsuitable or generalist parasitoids.French "Agence Nationale de la Recherche"French National Research Agency (ANR) [ANR-10-JCJC-1708 BICORAMICS]; EUEuropean Union (EU) [324475 COLBICS, 265865 PURE]; Turkey-France Cooperation grant CNRS-TUBITAK; INRA Plant Health and Environment DivisionInstitut National de la Recherche Agronomique (INRA)This work was funded by the French "Agence Nationale de la Recherche" (grant ANR-10-JCJC-1708 BICORAMICS), by the EU Seventh Framework Programme (grants Marie-Curie IAPP #324475 COLBICS and KBBE #265865 PURE), by a Turkey-France Cooperation grant CNRS-TUBITAK, and by the INRA Plant Health and Environment Division. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Data from: Intraspecific variability in the parasitoid wasp Trichogramma chilonis: can we predict the outcome of hybridization?

In the framework of biological control, the selection of effective natural enemies determines the final pest control. Thus, the genetic improvement of biocontrol agents could enhance the efficiency of biocontrol programs. Although promising, this approach has rarely been applied in this field. At the intraspecific level, hybridization between divergent populations of agents is expected to promote hybrid vigor (heterosis), but it is not clear to what extent. An even more difficult task is the ability to predict the fitness of hybrids from the biological characteristics of their parents. We investigated these general questions by crossing seven populations of the parasitoid wasp Trichogramma chilonis (Hymenoptera: Trichogrammatidae). Our results show different levels of mating compatibilities among populations, including asymmetric or almost complete reproductive isolation. Hybrids’ performance (fitness of the F1 generation) ranges from inbreeding depression to heterosis. It was possible, to some extent, to predict hybrid fitness from pairwise genetic and phenotypic distances among parents, in accordance with the “dominance” hypothesis. This may provide general guidelines for the genetic improvement of biological control agents

Diversity and geographic distribution of the indigenous and exotic parasitoids of the olive fruit fly, Bactrocera oleae (Diptera: Tephritidae), in Southern France

International audienceThe olive fruit fly, Bactrocera oleae (Dipt., Tephritidae), is the most important pest of olive crops in the world. Economic losses associated to the limited efficiency of pesticides and natural regulation require the development of new alternatives. A classical biological control program was thus implemented in 2007 in France with two main objectives : (1) test the efficiency of a new exotic parasitoid, Psyttalia lounsburyi (Hym., Braconidae) on the olive fruit fly populations and (2) understand how intraspecific hybridization could affect the demographic success of exotic biocontrol agents and, more generally, invasive species. In 2008, more than 43,000 P. lounsburyi were consequently introduced in 60 sites located in Southern France, covering the whole geographic distribution of olive crops in this country. The pluri-annual surveys realised between 2007 and 2010 gave the opportunity to better document the dynamics of olive fruit fly populations as well as the associated communities of parasitoids. Main results on these two topics are outlined here in a view to stimulate collaborative research and more precisely document the community ecology of B. oleae and its natural enemies in the Mediterranean area and elsewhere