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In Western Burkina Faso, fruit flies (Diptera: Tephritidae) cause economic impacts. Damage on a mango can reach 100% in late varieties, and on shea fruits, the average attack rate is 66.5%. Parasitoids offer natural biocontrol services, but the potential for this in Burkina Faso remains unknown. We performed a survey (2017–2019) in three plant formations (natural fallows n = 6; agroforestry parks n = 6 and mango orchards n = 6) to determine the levels of parasitism of tephritid fruit fly pests. For this purpose, fruits from cultivated and wild fruit fly host plant species were sampled in these plant formations and incubated for insects' emergence. In total, 1822 adults belonging to 7 parasitoid species were found. Fopius caudatus (Szépligeti) and Psyttalia concolor (Szépligeti) with 51.47% and 30.60% of the total of parasitoid adults emerged, respectively, were the most predominant. Parasitism rate varied according to host fruit species. Pupae recorded from Sarcocephalus latifolius and Vitellaria paradoxa were most parasitized (27.22% ± 3.96%) and (17.08% ± 2.37%), respectively, while those obtained from mangoes were the less parasitized (3.73% ± 0.91%). Mass rearing of F. caudatus and P. concolor, as well as habitat management, will contribute to the promotion of both, augmentation and conservation biological control.

International audience; The epidemiology of yam viruses remains largely unexplored. We present a large-scale epidemiological study of yam viruses in Guadeloupe based on the analysis of 1124 leaf samples collected from yams and weeds. We addressed the prevalence of cucumber mosaic virus (CMV), Cordyline virus 1 (CoV1), Dioscorea mosaic associated virus (DMaV), yam asymptomatic virus 1 (YaV1), yam mosaic virus (YMV), yam mild mosaic virus (YMMV), badnaviruses, macluraviruses and potexviruses, and the key epidemiological drivers of these viruses. We provide evidence that several weeds are reservoirs of YMMV and that YMMV isolates infecting weeds cluster together with those infecting yams, pointing to the role of weeds in the epidemiology of YMMV. We report the occurrence of yam chlorotic necrosis virus (YCNV) in Guadeloupe, the introduction of YMMV isolates through the importation of yam tubers, and the absence of vertical transmission of YaV1. We identified specific effects on some cropping practices, such as weed management and the use of chemical pesticides, on the occurrence of a few viruses, but no crop-related factor had a strong or general effect on the overall epidemiology of the targeted viruses. Overall, our work provides insights into the epidemiology of yam viruses that will help design more efficient control strategies.

Anticipating the establishment of pest reservoirs, and therefore pest infestation in sugarcane agrosystems, is a challenge for the implementation of integrated pest management (IPM) programs. The objective of this work was to develop a decision support system that suggests host plant species and pest natural enemies located in a production area. A knowledge base system (KBBI) was developed and coupled to DECIPESTS, a decision support system for PEST management in sugarcane. According to an observed damage, KBBI suggests the wild and cultivated plants that host the potential pests previously identified by DECIPESTS. The comparison with a local floristic inventory enables to determine pest reservoirs. Applied to a case study in Senegal, the system showed, for instance, that Eldana saccharina can be hosted by nine wild plant species located in the irrigation canals and two neighboring cultivated crops of socioeconomic importance in the area. This latter result indicates that the management of Eldana saccharina has to be tackled jointly by local farmers to be successful. While DECIPESTS uses a tactical approach to identify possible causes of pest infestation, its combination with KBBI makes it a strategic tool to enhance IPM strategy at a local scale.

The African weaver ant Oecophylla longinoda builds woven leaf nests inside tree canopies and is a major conservation biocontrol agent in sub-Saharan Africa. Weaver ant colonies provide well-protected and resource-rich environments for many associated trophobionts, thereby boosting their establishment on host plants. There is very little published literature on O. longinoda, their hosts plants and their associated trophobionts in West Africa. These tri-trophic interactions were studied over a period of four consecutive years (2010–2013) from south to north Benin. Our fieldwork revealed that all O. longinoda colonies were consistently associated with trophobionts. Oecophylla longinoda nests were recorded on 82 plant species belonging to 30 families, with 35 associated trophobiont species representing 11 families. Among cultivated plants, Mangifera indica was the most common species hosting O. longinoda, while Sarcocephalus latifolius the most frequent native one. Among trophobionts, Parasaissetia nigra, Udinia catori, Udinia farquharsoni (Coccidae) and Stictococcus sjostedti (Stictococcidae) were the most common hemipterans associated with O. longinoda. We identified a wide range of host plants that could be preserved (or planted) to promote the establishment of weaver ants to control different insect pests in fruit plantations in sub-Saharan Africa. When planted around fruit plantations with their nests and tended hemipterans, these host plants could facilitate biocontrol of mango fruit flies (Tephritidae) and cashew bugs (Coreidae, Miridae), by O. longinoda in the fruit plantations.

The South American tomato pinworm, Tuta absoluta (Meyrick), is one of the major threats to tomato production. Larvae can cause losses of more than 80% of production. It was officially detected for the first time in West Africa in 2012, in Senegal, and was subsequently reported in most countries in this part of the continent. To identify infested vegetable production areas and determine reservoir plants in Cote d'Ivoire, surveys were carried out and pheromone traps set in the North, South, East, West and Center in the main tomato production areas of the country. The pest was detected in all surveyed areas, with the highest number of males (623 ± 19.5 insects/week) caught by pheromone traps in Bouake in the Center of Cote d'Ivoire and a highest percentage of infested leaves, 96 ± 2.5%, was obtained in the locality of Agnibilekro in the East of the country. Tuta absoluta attacked all phenological stages of tomato plant in field. Larval mines were observed on the eggplant, Solanum melongena, the black nightshade, Solanum nigrum and the peppers, Capsicum annuum. Apart from tomato, T. absoluta seems to prefer S. melongena (41.64 ± 2.95% of infested leaves/plant; 4.88 ± 0.4 mine/plant) and S. nigrum (36.27 ± 3.42% of infested leaves/plant; 4.26 ± 0.6 mine/plant) more than C. annuum (13.48 ± 2.42% of infested leaves/plant and 1.38 ± 0.18 mine/plant). This study led to understanding that T. absoluta is well established in the main tomato production areas of Cote d’Ivoire, causing damage regardless of plant development stages and is present on other plant species.

This work is dedicated to Serge Quilici who has been leading prolific research on the tephritids of Reunion his whole career. This article has been reviewed and recommended by Peer Community in Ecology, https://doi.org/10.24072/pci.ecology.100080. The peer review history for this article is available at https://publo ns.com /publo n/10.1111/ele.13825.; International audience; The relative importance of ecological factors and species interactions for shaping species distributions is still debated. The realised niches of eight sympatric tephritid fruit flies were inferred from field abundance data using joint species distribution modelling and network inference, on the whole community and separately on three host plant groups. These estimates were then confronted the fundamental niches of seven fly species estimated through laboratory-measured fitnesses on host plants. Species abundances depended on host plants, followed by climatic factors, with a dose of competition between species sharing host plants. The relative importance of these factors mildly changed among the three host plant groups. Despite overlapping fundamental niches, specialists and generalists had almost distinct realised niches, with possible competitive exclusion of generalists by specialists on Cucurbitaceae. They had different assembly rules: Specialists were mainly influenced by their adaptation to host plants, while generalist abundances varied regardless of their fundamental host use.

14 Pág. (This article belongs to the Special Issue Integrating Science on Xanthomonas and Xylella for Integrated Plant Disease Management), Xanthomonas citri pv. citri (Xcc) and X. citri pv. aurantifolii (Xca) are causal agents of Citrus Bacterial Canker (CBC), a devastating disease that severely affects citrus plants. They are harmful organisms not reported in Europe or the Mediterranean Basin. Host plants are in the Rutaceae family, including the genera Citrus, Poncirus, and Fortunella, and their hybrids. In addition, other genera of ornamental interest are reported as susceptible, but results are not uniform and sometimes incongruent. We evaluated the susceptibility of 32 ornamental accessions of the Rutaceae family belonging to the genera Citrus, Fortunella, Atalantia, Clausena, Eremocitrus, Glycosmis, Microcitrus, Murraya, Casimiroa, Calodendrum, and Aegle, and three hybrids to seven strains of Xcc and Xca. Pathotyping evaluation was assessed by scoring the symptomatic reactions on detached leaves. High variability in symptoms and bacterial population was shown among the different strains in the different hosts, indicative of complex host–pathogen interactions. The results are mostly consistent with past findings, with the few discrepancies probably due to our more complete experimental approach using multiple strains of the pathogen and multiple hosts. Our work supports the need to regulate non-citrus Rutaceae plant introductions into areas, like the EU and Mediterranean, that are currently free of this economically important pathogen., This research was funded ORPRAMed Project on “Risk assessment of introduction of Xanthomonas citri subsp. citri through commercial trade of ornamental rutaceous plants in the Mediterranean basin”, ERA-NET ARIMNET 2-Call 2015.C.B., V.C. acknowledge the University of Catania for support under the projects “Investigation of phytopathological problems of the main Sicilian productive contexts and eco-sustainable defense strategies” (PIA.CE.RI. 2020–2022 Linea 2-Research Project MEDIT-ECO.); “Emergent Pests and Pathogens and Relative Sustainable Strategies” (Progetto di ricerca di Ateneo 2018-2020). O.P. and I.R. acknowledge the European Union (ERDF, EAFRD) and Réunion regional council for support

Les attaques de mouches des fruits sont la cause, chaque année, de nombreux dégâts sur les cultures fruitières et légumières dans les îles de l'océan Indien, et l'introduction non intentionnelle de nouvelles espèces représente toujours une menace supplémentaire de pertes importantes de récoltes. L'amélioration des méthodes de lutte contre les ravageurs passe notamment par une meilleure connaissance de ceux-ci et de leurs foyers potentiels de multiplication. Ce guide présente l'ensemble des plantes-hôtes des différentes espèces de mouches des fruits (Tephritidae), qui ont été recensées aux Comores, à Madagascar, à Maurice, à Mayotte, à La Réunion et aux Seychelles. Chaque plante-hôte est illustrée par des photos (fleurs, fruits, feuillage) et fait l'objet d'une brève description botanique ; les noms vernaculaires de ces plantes sont signalés dans les différentes langues et créoles de la zone. Les différentes espèces de mouches sont mentionnées pour chacune des plantes-hôtes et pour chacune des différentes îles. Sont présentées également des indications sur la qualité et l'importance du fruit vis-à-vis des mouches. De plus, des données sont proposées sur la répartition géographique, l'abondance et les périodes de fructification des plantes-hôtes. Enfin, sont présentés quelques éléments de taxonomie des espèces de mouches les plus communes dans les îles du Sud-Ouest de l'océan Indien.

In Western Burkina Faso, the host range of fruit flies was evaluated in three plant formations between May 2017 and April 2019. Samples of 61 potential hosts were collected and incubated for fruit fly emergence. Twenty-seven hosts including cultivated and wild fruit were identified. Among cultivated fruit species, mango, and guava were the most infested while high infestation incidences were observed in the fruit of the indigenous plants Vitellaria paradoxa, Annona senegalensis, Sarcocephalus latifolius, and Saba senegalensis. Low infestation rates were observed in Anacardium occidentale, Citrus species, Opilia celtidifolia, and Cissus populnea. The highest infestation index (1648.57 flies kg−1) was observed from V. paradoxa. Eleven new host fruit infested with many fruit fly species are reported in Burkina Faso. A total of 18 fruit fly species were reared; Bactrocera dorsalis (42.94%), Ceratitis cosyra (29.93%), and Ceratitis silvestrii (22.33%) dominated those that emerged. Four fruit fly species have been detected for the first time in Burkina Faso. The main suitable fruit hosts are abundant and available from May through August during the rainy season and become rare and have low infestation from November to April during the dry season. This is the first study of its kind in the region. This study shows that the three plant formations had an impact on population dynamics of the three tephritid species of economic importance in Western Burkina Faso. This information should be integrated into the development of a fruit fly pests management strategy.

Cacao (Theobroma cacao L.) was introduced into West Africa from South America during the nineteenth century. However, cacao swollen shoot disease (CSSD) was first observed in Ghana in 1936 and, later, discovered in Nigeria, Côte d’Ivoire, Togo, and Sierra Leone. The objectives of this work were to assess the genetic diversity and spatial distribution of the Cacao swollen shoot virus (CSSV) in Ghana and investigate the origin and spread of the virus by identifying alternative host plants. Results obtained from polymerase chain reaction amplifications and phylogenetic relationship analyses of infected cacao and alternative host plants collected from the cacao-growing regions in Ghana revealed the existence of nine CSSV groups, A, B, C, E, G, J, K, L and M, with six groups detected for the first time in Ghana. The CSSV groups in Ghana are very divergent and correspond to at least five different putative species, according to the International Committee on Taxonomy of Viruses recommendations (A, B-C complex, G, E, and M), with the M species only being detected in the alternate host Ceiba pentandra. The spatial distribution of the different molecular groups in Togo, Côte d’Ivoire, and Ghana makes it difficult to predict a single origin for CSSV among the West African cacao-growing countries.

BGPI : équipe 2 / 5; International audience; Efficient strategies for limiting the impact of pathogens on crops require a good understanding of the factors underlying the evolution of compatibility range for the pathogens and host plants, i.e., the set of host genotypes that a particular pathogen genotype can infect and the set of pathogen genotypes that can infect a particular host genotype. Until now, little is known about the evolutionary and ecological factors driving compatibility ranges in systems implicating crop plants. We studied the evolution of host and pathogen compatibility ranges for rice blast disease, which is caused by the ascomycete Magnaporthe oryzae. We challenged 61 rice varieties from three rice subspecies with 31 strains of M. oryzae collected worldwide from all major known genetic groups. We determined the compatibility range of each plant variety and pathogen genotype and the severity of each plant pathogen interaction. Compatibility ranges differed between rice subspecies, with the most resistant subspecies selecting for pathogens with broader compatibility ranges and the least resistant subspecies selecting for pathogens with narrower compatibility ranges. These results are consistent with a nested distribution of R genes between rice subspecies.

Characterization and expression profiling of microRNAs associated to host-plant adaptation in Lepidopteran pests of corn. 10. International workshop on molecular biology and genetics of the lepidoptera

Contexte : La spécificité à une plante hôte est un phénomène courant chez les insectes phytophages et notamment chez les pucerons. L’identité de l’hôte est par conséquent souvent utilisée dans l’identification des espèces, pour son côté pratique mais aussi pour des groupes chez lesquels peu de caractères morphologiques sont fiables. Ce problème est notamment important dans le cas des espèces cryptiques qui, par définition, ne présentent pas de différences morphologiques avec les espèces apparentées. Cependant, les populations d’une même espèce d’insecte vivant sur différentes plantes hôtes peuvent parfois montrer des différences phénotypiques induites par celles-ci. Par conséquent, bien que l’association avec une plante hôte puisse être un caractère diagnostique pratique, il peut aussi être trompeur dans la reconnaissance et la délimitation des espèces. L’utilisation de l’association avec un hôte comme caractère diagnostique est plus fiable quand les espèces en question sont bien décrites et délimitées en utilisant d’autres critères diagnostiques tels que des séquences ADN. Essigella (Insecta, Hemiptera, Sternorrhyncha, Aphididae, Lachninae) est un genre de pucerons regroupant treize espèces, dont deux avec deux sous-espèces chacune. Elles se nourrissent de phloème sur les aiguilles des pins (Pinus) et des douglas (Pseudotsuga). La plupart des espèces d’Essigella sont monophages et se développent sur une seule ou quelques espèces d’hôtes apparentés. Deux espèces d’Essigella, E. californica et E. pini, sont toutefois oligophages et sont trouvées sur plusieurs espèces de pins. Les espèces d’Essigella sont naturellement néarctiques. Une espèce, E. californica, a toutefois été accidentellement introduite dans plusieurs pays autour du monde, devenant dans certains cas, un important ravageur dans les plantations de pins. Essigella, Cinara, Eulachnus et Pseudessigella appartiennent à la tribu des Eulachnini, bien que les relations phylogénétiques entre ces genres n’aient pas encore été clarifiées. Les espèces d’Essigella présentent une forte variabilité morphologique intra- et interspécifique. De plus, il existe peu ou pas de caractères diagnostiques fiables, rendant la taxonomie de ce genre difficile. Plusieurs espèces ont été circonscrites par de subtiles variations morphologiques seulement détectables avec des mesures morphométriques et des analyses multivariées. Aussi, l’identification des espèces d’Essigella est traditionnellement basée sur la combinaison de la morphométrie et de l’identité de la plante hôte. Parce que la systématique d’Essigella n’a pas été testée par des moyens moléculaires, il est possible que certaines espèces proches morphologiquement et vivant sur des plantes hôtes apparentées correspondent en fait à des populations d’une même espèce. En même temps, il est également possible que différentes populations d’une présumée espèce puissent correspondre à différentes espèces cryptiques. Cette thèse présente une révision de la systématique d’Essigella en utilisant des données moléculaires et plus particulièrement les séquences ADN de quatre gènes : ATP6, COI, EF-1α et Gnd. Méthodes : J’ai estimé une phylogénie d’Essigella en utilisant le maximum de vraisemblance et l’inférence bayésienne avec les séquences ADN de quatre gènes : ATP6 et COI (mitochondriaux), EF-1α (nucléaire), et Gnd (de l’endosymbiote obligatoire Buchnera aphidicola). Des espèces représentatives des trois autres genres d’eulachnines ont été utilisées comme groupes externes. J’ai employé cinq méthodes de délimitation d’espèces dans le but de tester la taxonomie d’Essigella. Celles-ci furent la méthode traditionnelle du barcode utilisant COI avec un seuil de 2%, la méthode de l’« Automatic Barcode Gap Discovery » (ABGD), celle du « General Mixed Yule Coalescent » (GMYC), celle du « Bayesian Poisson Tree Process » (bPTP), ainsi que celle du « Refined Single Linkage » (RESL) via la base de données BOLD (Barcode of Life Data Systems). J’ai aussi comparé les séquences d’ATP6, COI, EF-1α et Gnd de populations exotiques d’E. californica avec celles de populations nord-américaines pour confirmer qu’elles appartenaient bien à cette espèce. Résultats : La phylogénie d’Essigella a montré que Pseudessigella était le groupe frère d’Essigella et qu’Eulachnus était le groupe frère du groupe Essigella + Pseudessigella. Cette phylogénie, combinée avec deux méthodes de délimitation d’espèces, ABGD et le barcode utilisant COI, a confirmé que toutes les espèces connues d’Essigella étaient valides et que par conséquent, les variations morphologiques observées étaient réellement spécifiques et non liées à la plante hôte. Aussi, les spécificités respectives de chaque espèce d’Essigella avec sa plante hôte ont été confirmées. Les analyses ont aussi révélé que les taxons connus comme E. californica et E. pini incluaient en réalité respectivement quatre et deux espèces, et que la base de données de BOLD renfermait les séquences de trois autres espèces non répertoriées. Dans le cas d’E. pini, l’espèce cryptique additionnelle correspond à son synonyme, E. patchae, qui ainsi a été rétablie. Dans le cas d’E. californica, les trois espèces nouvelles ne correspondent à aucun synonyme connu de l’espèce. Par conséquent, E. californica sensu lato inclut au moins quatre espèces distinctes, E. californica sensu stricto et trois autres décrites comme nouvelles : Essigella domenechi, E. gagnonae et E. sorenseni. À cause de la forte proximité morphologique entre les quatre espèces, et pour la première fois dans la taxonomie des pucerons, les différences nucléotidiques de séquences ADN (ATP6, COI et Gnd) sont utilisées comme caractères dans les diagnoses respectives de trois espèces nouvelles. Malgré la découverte de ces trois espèces, j’ai confirmé que seule E. californica sensu stricto avait été introduite en dehors de l’Amérique du Nord, et que les introductions se sont produites indépendemment et au moins quatre fois. Conclusion : Cette thèse a en grande partie confirmé la délimitation spécifique d’Essigella basée sur la morphométrie et la spécificité étroite de la plupart des espèces avec une plante hôte. Cependant, elle a aussi mis au jour l’existence de plusieurs espèces cryptiques et suggéré que de telles autres espèces pouvaient exister au sein d’Essigella, leur confirmation nécessitant un travail supplémentaire et un matériel additionnel substantiel. Cette étude souligne aussi que l’utilisation des données ADN comme caractères diagnostiques est essentielle dans la délimitation mais aussi dans la reconnaissance des espèces cryptiques., Background: Host plant specificity is a common phenomenon in phytophagous insects and notably in aphids. Host identity is therefore often used in species recognition, for its practicality but also for groups for which few morphological characters are reliable. This issue is notably important in the case of cryptic species that, by definition, exhibit no morphological difference with related species. However, populations of one same insect species living on different host plants can sometimes show host-mediated phenotypic differences. As a consequence, although host plant association can be a practical diagnostic character, it can also be misleading when recognizing and circumscribing species. The use of host association as a diagnostic character is most reliable when the species in question are well described and delimited using other diagnostic criteria such as DNA sequences. Essigella (Insecta, Hemiptera, Sternorrhyncha, Aphididae, Lachninae) is an aphid genus encompassing thirteen species, two of which have two subspecies each. They are phloem-feeders on the needles of true pines (Pinus) and Douglas firs (Pseudotsuga). Most Essigella species are monophagous and develop on a single or a few closely-related host species. Two species of Essigella, E. californica and E. pini, are oligophagous, however, and found on several pine species. Essigella species are naturally Nearctic. One species, E. californica, has however been accidentally introduced in several countries around the world, becoming in some instances an important pest in pine plantations. Essigella, Cinara, Eulachnus and Pseudessigella comprise the tribe Eulachnini, although the phylogenetic relationships between these genera have not yet been clarified. Essigella species exhibit high intra- and interspecific morphological variability. Moreover, there exists few or no diagnostic reliable characters, making the taxonomy of the genus difficult. Several species were circumscribed by subtle morphological variations only detectable with morphometric measurements and multivariate analyses. Thus, identification of Essigella species has traditionally been based on a combination of morphometry and host plant identity. Because Essigella systematics has not been tested with molecular means, it is likely that some morphologically close species living on related host plants actually correspond to populations of a single species. At the same time, it is also possible that different populations of one apparent species may actually correspond to different cryptic species. This thesis presents a revision of Essigella systematics using molecular data and more particularly DNA sequences of four genes: ATP6, COI, EF-1α and Gnd. Methods: I estimated a phylogeny of Essigella using maximum likelihood and Bayesian inference using DNA sequences of four genes: ATP6 and COI (mitochondrial), EF-1α (nuclear), and Gnd (from the obligate endosymbiont Buchnera aphidicola). Representative species of the three other eulachnine genera were used as outgroups. I employed five species delimitation methods in order to test the species taxonomy of Essigella: the traditional 2% COI barcode threshold, the Automatic Barcode Gap Discovery (ABGD), the General Mixed Yule Coalescent (GMYC), the Bayesian Poisson Tree Process (bPTP), and the Refined Single Linkage (RESL) via the BOLD (Barcode of Life Data Systems) database. I also compared ATP6, COI, EF-1α and Gnd sequences from exotic E. californica populations with sequences of North American ones to confirm they actually belongs to that species. Results: The Essigella phylogeny showed that Pseudessigella is the sister-group of Essigella and that Eulachnus is the sister group of Essigella + Pseudessigella. That phylogeny, combined with two species delimitation methods, ABGD and COI barcoding, confirmed that all known Essigella species were valid and, as a result, morphological variations were truly specific and not linked to the host plant. Thus, respective specificity between Essigella species and their host plant were confirmed. The analyses also revealed that the taxa known as E. californica and E. pini actually include four and two cryptic species, respectively, and that the BOLD database contained sequences of three other unknown species. In the case of E. pini, the additional cryptic species corresponds to its synonym, E. patchae, which I thus re-established. In the case of E. californica, the three new species do not correspond to any known synonym of the species. Thus E. californica sensu lato includes at least four distinct species, E. californica sensu stricto and three others described as new: Essigella domenechi, E. gagnonae and E. sorenseni. Because of the strong morphological proximity between the four species, and for the first time in aphid taxonomy, nucleotide differences in DNA sequences (ATP6, COI and Gnd), are used in the respective diagnoses of the three new species. Despite discovery of these three species, I confirmed that only E. californica sensu stricto was introduced outside North America, and that the introductions occurred independently and at least four times. Conclusion: This thesis largely confirmed the morphometrics-based species delimitation of Essigella and the narrow host plant specificity of most of the species. However, it also uncovered the existence of several cryptic species and suggested that other such species may exist within Essigella, confirmation requiring further work and substantial additional material. This study also highlights that the use of DNA data as diagnostic characters is essential in delimiting but also in recognizing cryptic species.

Background Divergent selection has been shown to promote speciation in many taxa and especially in phytophagous insects. In the Ostrinia species complex, the European corn borer (ECB) and adzuki bean borer (ABB) are two sibling species specialized to different host plants. The first is a well-known maize pest, whereas the second is a polyphagous species associated with various dicotyledons. Their specialization to host plants is driven by morphological, behavioral and physiological adaptations. In particular, previous studies have shown that ECB and ABB display marked behavior with regard to plant choice during oviposition, involving specific preference and avoidance mechanisms. In this study, our goal was to identify the mechanisms underlying this host-plant specialization in adult females through an analysis of their gene expression. We assembled and annotated a de novo reference transcriptome and measured differences in gene expression between ECB and ABB females, and between environments. We related differentially expressed genes to host preference behavior, and highlighted the functional categories involved. We also conducted a specific analysis of chemosensory genes, which are considered to be good candidates for host recognition before oviposition. Results We recorded more differentially expressed genes in ECB than in ABB samples, and noticed that the majority of genes potentially involved in the host preference were different between the two species. At the functional level, the response to plant environment in adult females involved many processes, including the metabolism of carbohydrates, lipids, proteins, and amino acids; detoxification mechanisms and immunity; and the chemosensory repertoire (as expected). Until now, most of the olfactory receptors described in Ostrinia spp. had been tested for their putative role in pheromone recognition by males. Here we observed that one specific olfactory receptor was clearly associated with ECB’s discrimination between maize and mugwort conditions, highlighting a potential new candidate involved in plant odor discrimination in adult females. Conclusions Our results are a first step toward the identification of candidate genes and functions involved in chemosensory processes, carbohydrate metabolism, and virus and retrovirus dynamics. These candidates provide new avenues for research into understanding the role of divergent selection between different environments in species diversification.

International audience

Background: A change in the environment may impair development or survival of living organisms leading them to adapt to the change. The resulting adaptation trait may reverse, or become fixed in the population leading to evolution of species. Deciphering the molecular basis of adaptive traits can thus give evolutionary clues. In phytophagous insects, a change in host-plant range can lead to emergence of new species. Among them, Spodoptera frugiperda is a major agricultural lepidopteran pest consisting of two host-plant strains having diverged 3 MA, based on mitochondrial markers. In this paper, we address the role of microRNAs, important gene expression regulators, in response to host-plant change and in adaptive evolution.[br/] Results: Using small RNA sequencing, we characterized miRNA repertoires of the corn (C) and rice (R) strains of S. frugiperda, expressed during larval development on two different host-plants, corn and rice, in the frame of reciprocal transplant experiments. We provide evidence for 76 and 68 known miRNAs in C and R strains and 139 and 171 novel miRNAs. Based on read counts analysis, 34 of the microRNAs were differentially expressed in the C strain larvae fed on rice as compared to the C strain larvae fed on corn. Twenty one were differentially expressed on rice compared to corn in R strain. Nine were differentially expressed in the R strain compared to C strain when reared on corn. A similar ratio of microRNAs was differentially expressed between strains on rice. We could validate experimentally by QPCR, variation in expression of the most differentially expressed candidates. We used bioinformatics methods to determine the target mRNAs of known microRNAs. Comparison with the mRNA expression profile during similar reciprocal transplant experiment revealed potential mRNA targets of these host-plant regulated miRNAs.[br/] Conclusions: In the current study, we performed the first systematic analysis of miRNAs in Lepidopteran pests feeding on host-plants. We identified a set of the differentially expressed miRNAs that respond to the plant diet, or differ constitutively between the two host plant strains. Among the latter, the ones that are also deregulated in response to host-plant are molecular candidates underlying a complex adaptive trait.

This paper reviews all available information regarding the occurrence and biology of the melon fly, Zeugodacus cucurbitae (Coquillett), in the Afrotropical Region, including data on invasion history, distribution patterns, population genetics, host range, and interspecific competition. Although limited intraspecific variability has been observed within the region regarding the above mentioned aspects, there seems to be no indication that Zeugodacus cucurbitae represents a species complex. A checklist of all of the species included in Zeugodacus as recently proposed by Virgilio et al. (2015) is provided.

International audience; In plants, host response to pathogenic microbes is driven both by microbial perception and detection of modified-self. The Xanthomonas campestris effector protein AvrAC/XopAC uridylylates the Arabidopsis BIK1 kinase to dampen basal resistance and thereby promotes bacterial virulence. Here we show that PBL2, a paralog of BIK1, is similarly uridylylated by AvrAC. However, in contrast to BIK1, PBL2 uridylylation is specifically required for host recognition of AvrAC to trigger immunity, but not AvrAC virulence. PBL2 thus acts as a decoy and enables AvrAC detection. AvrAC recognition also requires the RKS1 pseudokinase of the ZRK family and the NOD-like receptor ZAR1, which is known to recognize the Pseudomonas syringae effector HopZ1a. ZAR1 forms a stable complex with RKS1, which specifically recruits PBL2 when the latter is uridylylated by AvrAC, triggering ZAR1-mediated immunity. The results illustrate how decoy substrates and pseudokinases can specify and expand the capacity of the plant immune system.

International audience; A potential strategy for controlling pests is through the use of "companion plants" within a crop system. This strategy has been used in several trials to fight against a major crop insect pest: the aphid. We reviewed the literature to highlight the major mechanisms by which a companion plant may act. Trials carried out under laboratory or field conditions revealed that companion plants operate through several mechanisms. A companion plant may be associated with a target crop for various reasons. Firstly, it can attract aphids and draw them away from their host plants. Secondly, it can alter the recognition of the host plant. This effect is mostly attributed to companion plant volatiles since they disturb the aphid host plant location, and additionally they may react chemically and physiologically with the host plant, making it an unsuitable host for aphids. Thirdly, it can attract natural enemies by providing shelter and food resources. In this review, the feasibility of using companion plants is discussed. We conclude that many factors need to be taken into account for a successful companion plant strategy. For the best long-term results, companion plant strategies have to be combined with other alternative approaches against aphids.

Phytophagous insects are a very diverse group of organisms and most of them are considered as specialized. Patterns of specialization regarding their host plants depend on their ability to interact with their hosts (fundamental niche) and on environmental factors which modulate these interactions leading to observed patterns in the field (realized niche). Fundamental specialization is determined by the joint evolution of two traits: larval performance and female preference. To understand this specialization, we studied a community of eight fruit fly species (Diptera: Tephritidae) present in La Réunion.First, we determined the realized niche of each species and showed that they were structured by plant phylogeny with D. demmerezi, D. ciliatus and Z. cucurbitae as Cucurbitaceae specialists, N. cyanescens as Solanaceae specialist and C. catoirii, C. capitata et C. quilicii as generalists feeding on plants belonging to different families. After the invasion of B. zonata in 2000, C. capitata et C. quilicii were subjected to a decrease of their host range.Then, we determined the fundamental niche of these species (except D. ciliatus). We assessed female preferences by measuring their fecundity on 29 fruits, then we tested the presence of a correlation between female preference and larval performance (mother knows best hypothesis). We showed a positive correlation for Cucurbitaceae specialists laying eggs on plants where larvae survive the best, at the opposite of generalist species laying eggs and surviving on many hosts without any correlation between these two traits.Finally, host selection by females being mostly done thanks to volatile organic compounds (VOCs) emitted by fruits, we showed that fruits infested by generalist species have common VOCs responsible for fruit maturation. On the contrary, the fruits of several Solanaceae emit specific VOCs suggesting their detection by N. cyanescens females. Cucurbitaceae species emit abundant VOCs rarely present in other families suggesting a detection of a specific blend of these VOCS by Cucurbitaceae specialists., Les insectes phytophages forment un groupe d’organismes très diversifié et la plupart sont considérés comme spécialistes. Les patrons de spécialisation des insectes vis à vis de leurs plantes hôtes dépendent en partie de leur capacité à interagir avec les plantes (niche fondamentale) et aux facteurs environnementaux modulant ces interactions et aboutissant aux observations en milieu naturel (niche réalisée). La spécialisation fondamentale est déterminée par l'évolution conjointe de deux traits : la performance des larves et la préférence des femelles. Pour comprendre cette spécialisation, nous avons étudié une communauté de huit espèces de mouches des fruits (Diptera : Tephritidae) présentes à La Réunion. Dans un premier temps, nous avons déterminé la niche réalisée de chaque espèce et montré que ces niches étaient structurées par la phylogénie des plantes avec D. demmerezi, D. ciliatus et Z. cucurbitae spécialistes des Cucurbitaceae, N. cyanescensspécialiste des Solanaceae et C. catoirii, C. capitata et C. quilicii généralistes attaquant des plantes de différentes familles. Après l'invasion de B. zonata en 2000, C. capitata et C. quilicii ont subi une réduction de leur gamme d'hôtes. Dans un deuxième temps, nous avons déterminé la niche fondamentale de ces espèces (sauf D. ciliatus). Nous avons évalué les préférences des femelles en mesurant la fécondité de chacune d’entre elles sur une gamme de 29 fruits, puis nous avons testé l'existence d'une corrélation entre la préférence des femelles et la performance des larves (mother knows best hypothesis). Nous avons montré une corrélation positive chez spécialistes des Cucurbitaceae qui pondent sur les plantes pour lesquelles les larves survivent le mieux contrairement aux généralistes pondant et survivant sur une large gamme d'hôtes mais sans corrélation entre ces deux traits.Enfin, la sélection de l'hôte par les femelles se faisant principalement grâce aux composés organiques volatils (COVs) émis par les fruits, nous avons montré que les fruits infestés par les généralistes ont pour point commun l'émission de COVs responsables de la maturation des fruits. Au contraire, les fruits de plusieurs Solanaceae émettent des COVs spécifiques suggérant la détection de ceux-ci par les femelles de N. cyanescens. Les Cucurbitaceae émettent des COVs abondants peu présents dans les autres familles suggérant une détection d'un mélange spécifique de ces COVs par les Tephritidae spécialistes des Cucurbitaceae.

After 2007, upsurges of whiteflies on cassava plants and high incidences of cassava diseases were observed in Central African Republic. This recent upsurge in the abundance of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) was directly linked to serious damage to cassava crops resulting from spread of whitefly-borne cassava mosaic geminiviruses (CMGs). There is currently very little information describing whitefly populations on cassava and associated crops in Central African Republic. The current study aimed to address this gap, and to determine whether the increasing damage associated with B. tabaci whiteflies was the consequence of a new invasion, or an upsurge of a local population. The molecular genetic identification and phylogenetic relationships of 898 B. tabaci adult individuals collected from representative locations (54) throughout CAR were determined based on their mitochondrial cytochrome oxidase I sequences (mtCOI). Field and ecological data were also collected from each site, including whitefly abundance, CMD incidence, host plants colonized by B. tabaci and agro-ecological zone. Phylogenetic analysis of the whitefly mtCOI sequences indicated that SSA1 (-SG1, -SG2), SSA3, MED, MEAM1 and Indian Ocean (IO) putative species occur in CAR. One specific haplotype of SSA1-SG1 (SSA1-SG1-P18F5) predominated on most cassava plants and at the majority of sites. This haplotype was identical to the SSA1-SG1 Mukono8-4 (KM377961) haplotype that was recorded from Uganda but that also occurs widely in CMD pandemic-affected areas of East Africa. These results suggest that the SSA1-SG1-P18F5 haplotype occurring in CAR represents a recent invasive population, and that it is the likely cause of the increased spread and severity of CMD in CAR. Furthermore, the high mtDNA sequence diversity observed for SSA1 and its broad presence on all sites and host plants sampled suggest that this genetic group was the dominant resident species even before the arrival of this new invasive haplotype.

The invasive tomato leafminer, Tuta absoluta (Meyrick) (Lepidoptera, Gelechiidae) has become a real threat for the continued production of tomatoes across Sub-Saharan Africa since its first detection in Senegal. However, little is known of its geographical expansion, seasonal population dynamics, and damage to crops. A trapping network was deployed in 2014 and 2015 in Senegal to monitor the dynamics of T. absoluta populations at a regional and nationwide scale. A field network was also implemented in the most infested area to get information on the pest incidence during the 2013–2014 cropping season. In 2014, pheromone traps did not detect the presence of T. absoluta moths in remote areas of Eastern Senegal. In 2015, moths were detected in all the fifteen monitored areas deployed throughout the country. Abundance of trapped moths was greatest in 'Niayes', the main tomato-producing area. Unexpectedly, T. absoluta moths were trapped in some areas with few or no tomato crops, including off-season in the 'Vallee du fleuve', hot drylands ('Matam' and 'Kidira') and urban environments ('Dakar'). This suggests high mobility of moth populations and capacity to survive in harsh environments and to persist on alternative host plants. Field monitoring in the main tomato-producing area showed a very low incidence of T. absoluta over the early dry season (0–2% mined leaves), followed by severe outbreaks during the late dry season (up to 60% mined leaves). Results on the invasive pest occurrence will be helpful to decision-makers with a view to develop alternative strategies such as biological control by indigenous natural enemies or collective management strategies based on the temporal or spatial exclusion of host crops. (Resume d'auteur)