Helene Delatte

• PhD
• Researcher at French Agricultural Research Centre for International Development

Eucalyptus species are widely planted for their rapid growth, high timber and commercial cellulose fiber. Several Eucalyptus pests have spread around the world, generally without their natural enemies. The present study was carried out on Madagascar and the Mascarene islands (Mauritius and Reunion), located in the southwestern Indian Ocean, on new...

Plant pathogens can alter the behavior of their insect vectors as well as their survival and reproduction. The African psyllid, Trioza erytreae, is one of the vectors of Huanglongbing, a citrus disease caused mainly by "Candidatus Liberibacter asiaticus" (CLas). The purpose of this study was to characterize the effects of CLas on the psyllid, T. er...

The honey bee Apis mellifera has shown a great intraspecific diversity, together with a variability of its life history traits. The development of the brood has been well documented in temperate but much less in tropical subspecies, but a limited number of studies focused on tropical subspecies. This study measures the post-capping period of A. mel...

The microsporidian Vairimorpha (Nosema) ceranae is one of the most common parasites of the honeybee. A single honeybee carries many parasites and therefore multiple alleles of V. ceranae genes that seem to be ubiquitous. As a consequence, nucleotide diversity analyses have not allowed discriminating genetic structure of parasite populations. We per...

Novel transmission routes can allow infectious diseases to spread, often with devastating consequences. Ectoparasitic varroa mites vector a diversity of RNA viruses, having switched hosts from the eastern to western honey bees (Apis cerana to Apis mellifera). They provide an opportunity to explore how novel transmission routes shape disease epidemi...

Background Thermal history may induce phenotypic plasticity in traits that affect performance and fitness. One type of plastic response triggered by thermal history is acclimation. Because flight is linked to movement in the landscape, trapping and detection rates, and underpins the success of pest management tactics, it is particularly important t...

Outbreaks of whitefly, Bemisia tabaci species in East and Central Africa, have become increasingly prevalent during the previous 25 years and are responsible for driving the spread of plant-virus diseases, such as cassava mosaic disease and cassava brown steak disease. Epidemics of these diseases have expanded their ranges over the same period, spr...

In biological control strategies, the use of a combination of biological control agents leads to the necessity to test whether the biological control agents are compatible in term of survival and efficacy. Nesidiocoris tenuis and N. volucer are two miridae used as biological control agents, but N. tenuis can become a pest because of its necrotic sa...

Novel transmission routes can allow infectious diseases to spread, often with devastating consequences. Ectoparasitic varroa mites vector a diversity of RNA viruses and, having switched hosts from the eastern to western honey bees (Apis cerana to Apis mellifera). They provide an opportunity to explore how novel transmission routes shape disease epi...

When several polyphagous herbivore species share a parasitoid, the tri-trophic interaction networks can be difficult to predict. In addition to direct effects, the parasitoid may influence the herbivore community by mediating indirect interactions among hosts. The plant species can also modulate the parasitoid preference for a specific host. One of...

Crop losses from pests threaten global food security and safety. In the last six decades, pest control using chemical pesticides has resulted in important yield gains per unit area, worldwide. However, the long-term sustainability of chemical pest control has been increasingly thrown into doubt due to the negative impact on human health, biodiversi...

An increasing number of invasive fruit fly pests are colonizing new grounds. With this study, we aimed to uncover the invasion pathways of the oriental fruit fly, Bactrocera dorsalis into the islands of the Indian Ocean. By using genome‐wide SNP data and a multipronged approach consisting of PCA, ancestry analysis, phylogenetic inference, and kinsh...

Introduction Huanglonbing (HLB) is the most serious disease of citrus in the world, associated with three non-cultivable phloem-restricted bacteria Candidatus Liberibacter asiaticus (CLas), Ca L. africanus (CLaf) and Ca L. americanus (CLam). CLas is transmitted by the Asian citrus psyllid Diaphorina citri, and has spread to several countries. The A...

Introduction The oriental fruit fly Bactrocera dorsalis is one of the most destructive agricultural pests worldwide, with highly debated species delimitation, origin, and global spread routes. Objectives Our study intended to (i) resolve the taxonomic uncertainties between B. dorsalis and B. carambolae, (ii) reveal the population structure and glo...

Background Aedes albopictus is a public health threat for its worldwide spread and ability to transmit arboviruses. Understanding mechanisms of mosquito immunity can provide new tools to control arbovirus spread. The genomes of Aedes mosquitoes contain hundreds of nonretroviral endogenous viral elements (nrEVEs), which are enriched in piRNA cluster...

Insects harbor a diversity of microbes that are known to affect their host’s response to biotic and abiotic stressors. This is important in the context of climate change and human-caused habitat alterations, during which drastic changes are so rapid that organisms have little time to adapt. Symbionts often accompany invading species, and might play...

Sap-sucking insects, including whiteflies, are amongst the most devastating and widely distributed organisms on the planet. They are often highly invasive and endosymbiont communities within these insects help them adapt to new or changing environments. Bemisia tabaci (Gennadius; Hemiptera: Aleyrodidae) whitefly species are vectors of more than 500...

Background Aedes albopictus is a public health threat for its worldwide spread and ability to transmit arboviruses. Understanding mechanisms of mosquito immunity can provide new tools to control arbovirus spread. The genomes of Aedes mosquitoes contain hundreads of nonretroviral endogenous viral elements (nrEVEs), which are enriched in piRNA cluste...

While contemporary changes in feeding preferences have been documented in phytophagous insects, the mechanisms behind these processes remain to be fully clarified. In this context, the insect gut microbiome plays a central role in adaptation to novel host plants. The cucurbit frugivorous fruit fly Zeugodacus cucurbitae (Diptera, Tephritidae) has oc...

Invasions by exotic species in areas already occupied by related species may lead to extinction or niche partitioning. Bactrocera dorsalis has invaded the Comoros archipelago in 2005 where other tephritids were already present. The host ranges of fruit flies in the Comoros were studied by conducting a seven-year survey on the three islands of the a...

The invasion success of a species in an agrosystem is greatly influenced by environmental factors such as the use of insecticides, by the intrinsic evolutionary capabilities of the species, and also by interactions with resident species. On the island of La Réunion, the successive invasions of MEAM1 and MED whitefly species over the last 20 years h...

Whiteflies are one of the major pests of tomato under greenhouses, and their control partly relies on biocontrol strategies. Among those biocontrol agents, parasitoids or predators are widely used. However, the introduction of a biocontrol agent in a new area is not trivial. For that reason, we investigated the use of a tropical native mirid, Nesid...

Introduction – Determining the host status of fruit species for a given fruit fly species is essential to decide on its risk for the international trade of fresh fruits. This study aims to determine if Bactrocera dorsalis, the Oriental fruit fly, can infest fruits of four commercial species grown for exportation: Citrus aurantifolia, Citrus hystrix...

A minimum of 13 diverse whitefly species belonging to the Bemisia tabaci (B. tabaci) species complex are known to infest cassava crops in sub‐Saharan Africa (SSA), designated as SSA1‐13. Of these, the SSA1 and SSA2 are the predominant species colonizing cassava crops in East Africa. The SSA species of B. tabaci harbor diverse bacterial endosymbiont...

• 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...

Agriculture is one of the major farming activities, representing 32% of the gross domestic product of Madagascar and 74.3% of the population is involved in this activity. Fruit flies of the Tephritidae family are considered as the most destructive pests for agriculture in the country, nevertheless, few data exist on host plants and distribution of...

The genetic contribution to phenotypic variation (namely the heritability) affects the response to selection. In honeybee, the haplodiploid sex determination does not allow the straightforward use of classical quantitative genetics methods to estimate heritability and genetic correlation. Nevertheless, specific methods have been developed for about...

The Asian citrus psyllid, Diaphorina citri, is a major threat to citrus production worldwide, as it transmits ‘Candidatus Liberibacter asiaticus’, the pathogen associated with the devastating Asian form of huanglongbing. The psyllid has spread widely from its native South Asia during the past 300 years, most recently to Africa. We report the first...

The previous genetic characterization of the honeybee population of Mauritius Island (Indian Ocean) revealed an ongoing process of hybridization between the first established African subspecies Apis mellifera unicolor and recently imported European subspecies (A. m. ligustica, A. m. carnica and A. m. mellifera). This context offers the rare opportu...

Aim: In a context of successive fruit fly invasions (Tephritidae), this study investigated how the top invader, Bactrocera dorsalis, displaced established fruit fly populations. We focused, particularly, on how this invasion impacted the host range and climatic niche of each resident species. Location: La Réunion, France, Indian Ocean. Methods: We...

‘Candidatus Liberibacter asiaticus’ (CLas) is an insect-transmitted, phloem-restricted α-proteobacterium associated with huanglongbing (HLB). Here, we provide the whole genome sequence of CLas strain, ReuSP1, from its insect vector Diaphorina citri (Hemiptera: Liviidae) collected in La Réunion. The genome is composed of 1,230,064 bp and has a 36.5%...

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 inf...

High populations of African cassava whitefly (Bemisia tabaci) have been associated with epidemics of two viral diseases in Eastern Africa. We investigated population dynamics and genetic patterns by comparing whiteflies collected on cassava in 1997, during the first whitefly upsurges in Uganda, with collections made in 2017 from the same locations....

BACKGROUND Global and intensive use of insecticides has led to the emergence and rapid evolution of resistance in the major pest Bemisia tabaci (Gennadius). In La Réunion, an island of the South West Indian Ocean, three whitefly species coexist, two of which are predominant, the indigenous Indian Ocean (IO) and the invasive Middle East Asia Minor 1...

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

The 37 currently recognized Bemisia tabaci cryptic species are economically important species and contain both primary and secondary endosymbionts, but their diversity has never been mapped systematically across the group. To achieve this, PacBio sequencing of full-length bacterial 16S rRNA gene amplicons was carried out on 21 globally collected sp...

The honeybee (Apis mellifera) has to cope with multiple environmental stressors, especially pesticides. Among those, the herbicide glyphosate and its main metabolite, the aminomethylphosphonic acid (AMPA), are among the most abundant and ubiquitous contaminant in the environment. Through the foraging and storing of contaminated resources, honeybees...

Cumulative proportion of surviving honeybees chronically exposed to glyphosate (A), AMPA (B), stoichiometric mixes of glyphosate and AMPA (C) in summer, or exposed to glyphosate and/or N. ceranae in winter (D). Glyphosate (GLY) and aminomethylphosphonic acid (AMPA) were added in the feeding sugar syrup, and spores of N. ceranae were orally administ...

Primers used in the study. (PDF)

Growth of S. alvi strains IHP.IC1 (filled triangles) and IHP.IO2 (open circles) isolated from honeybee guts in the presence of glyphosate. Strains were inoculated in HIB medium in the presence of increasing concentrations of glyphosate. After 48h of growth under anaerobic conditions, the optical density (OD) of the cultures was measured at 600 nm....

Phylogenetic analysis (A) and conserved amino acids (B) of 5-enolpyruvylshikimate-3-phosphate synthases (EPSPS). (A) amino acid sequences were taken from a previously reported phylogenetic tree [1], and sequences of species phylogenetically related to the isolated strains were selected in GenBank. E. coli MurA sequence was used as an outgroup belon...

Daily mean sucrose (A) and herbicide (B) consumption of honeybees chronically exposed to glyphosate and/or AMPA in summer or to glyphosate and/or N. ceranae in winter. Glyphosate (GLY) and aminomethylphosphonic acid (AMPA) were added in the feeding sugar syrup, and spores of N. ceranae were orally administrated the day preceding the experiment. Con...

Principal component analyses of QPCR data (A) for control and 1.5 mM glyphosate-treated samples in summer and winter, and (B) for glyphosate- and AMPA-treated samples in summer. Analyses were performed using the normalized CQ (relative to total bacterial content). In order to avoid redundant data for the same taxa, values obtained using Lactobacill...

Evolutionary relationships within Snodgrassella alvi (A) and Gilliamella apicola (B) species. 16S nucleotide sequences were taken from GenBank and from Motta et al. [1], the latter being indicated with genome accession numbers. K. negevensis (A) and O. hercynius (B) were chosen as outgroups. Sequences were aligned using ClustalW and trimmed to 957...

Strains isolated from honeybee guts. (PDF)

Hypotheses about the worldwide colonization routes of the melon fly, Zeugodacus cucurbitae (Diptera: Tephritidae), are mainly based on sparse historical records. Here we aim at reconstructing the colonization history of the African continent based on an improved description of the population structure of Z. cucurbitae and approximate Bayesian analy...

This is the first description of the complete genome sequence of a new monopartite begomovirus isolated from tomato with symptoms of tomato (yellow) leaf curl disease collected in the Seychelles. The DNA-A-like nucleotide sequences share the highest nucleotide sequence identity (84%) with tomato leaf curl Anjouan virus (ToLCAnjV) from the Comoros i...

Honey bees are facing many serious threats, and Varroa destructor is of major worldwide concern. V. destructor was first observed in 2010 in the south–west Inidan Ocean island of Madagascar. Varroa spp. was first suspected in Mauritius in late July 2014. Two surveys were conducted in September and November 2014 in Mauritius and Rodrigues. The aims...

The Ceratitis FAR complex (Diptera, Tephritidae) includes four economically important frugivorous flies ( Ceratitis anonae , Ceratitis fasciventris , Ceratitis quilicii , Ceratitis rosa ) whose immature stages and adult females cannot be properly resolved through morphological identification. In order to develop a simplified molecular tool for the...

Insect‐plant associations and their role in diversification are mostly studied in specialists. Here, we aimed to identify macroevolution patterns in the relationships between generalists and their host plants that have the potential to promote diversification. We focused on the Bemisia tabaci species complex containing more than 35 cryptic species....

The morphological diversity of pollen brings important information on the taxonomy of plants present in past and current ecosystems. Regarding the rich biodiversity and the large number of endemic plant species on the island of Madagascar, pollen reference collections are still scarce for this part of the world. The main objective of this study was...

Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a pest species complex that causes widespread damage to cassava, a staple food crop for millions of households in East Africa. Species in the complex cause direct feeding damage to cassava and are the vectors of multiple plant viruses. Whilst significant work has gone into developing virus-resi...

With globalization the Western honey bee has become a nearly cosmopolitan species, but it was originally restricted to the Old World. This renowned model of biodiversity has diverged into five evolutionary lineages and several geographic “subspecies.” If Apis mellifera unicolor is indubitably an African subspecies endemic to Madagascar, its relatio...

Sampling effort represented by allele accumulation curves for 14 microsatellite loci in La Réunion, Mauritius, and the Comoros Islands, compared to other insular and continental populations. (A) Overall sampling size scale and (B) comparative lower scale. Only the three largest continental populations of Italy, France, and South Africa are represen...

Mean number of alleles per locus (14 microsatellites) within La Réunion and Mauritius (sites with n ≥ 5). (TIF)

Distribution of honey bee colony sampling sites in Madagascar, and the Seychelles and Mascarenes archipelagos. First line and from left to right: Geographic positions of 127 sampling sites from La Réunion, 31 from Mauritius, and 20 from Rodrigues in the Mascarenes Archipelago. Second line and from left to right: Geographic positions of the 81 sampl...

Distribution of honey bee colony sampling sites in the four islands of the Comoros Archipelago. (TIF)

Coexistence of two genetic clusters and hybrid honey bees in Mauritius (N = 367), based on 14 microsatellite loci. A) STRUCTURE bar plots at K = 2 and 3. Sites are separated by black lines and are ordered from MUS01 to 31. Maternal origin (top) for each individual (evolutionary lineage, A, C, or M) defined by the DraI test on the COI-COII intergeni...

Complete sample database, including sample IDs, location coordinates, mtDNA COI-COII DraI profiles, and multi-locus genotypes determined at 14 microsatellite loci. (XLSX)

Pairwise FST values among sites from Zimbabwe (ZWE), France (FRA), and Italy (ITA) with N ≥ 5, based on 14 microsatellites. After Bonferroni corrections, permutations tests were only significant among French sites (in bold P < 0.000549). Colors as in Table 3. (DOCX)

Pairwise FST values among sites at Mauritius Island with N ≥ 5 based on 14 microsatellites. Statistical significance for the permutation tests after Bonferroni corrections is indicated in bold (P < 0.000476). Colors as in Table 3. (DOCX)

European and African samples are good representative outgroups for native honey bee populations structured using the distribution of mtDNA lineages. A) STRUCTURE bar plots (K = 2 to 5) for 263 honey bee colonies sampled in Africa and Europe, inferred from 14 microsatellite loci. Each vertical line represents the posterior assignment probability of...

Absence of population structure in the 2,050 honey bee colonies sampled from 127 sites at La Réunion, based on 14 microsatellite loci. A) STRUCTURE bar plots at K = 2, B) Average likelihood of runs in STRUCTURE L(K) along with number of clusters (K) for La Réunion. C) ΔK, estimator of the optimal number of clusters (K) according to Evanno et al. (5...

DAPC barplots of the Western honey bee populations from southwest Indian Ocean islands at global scale. DAPC bar plots are presented for K = 3 to 8, based on 4,388 honey bees. (TIF)

Mitochondrial COI-COII intergenic region diversity (based on DraI restriction profiles) and nuclear diversity indices for each SWIO, African, and European sampling site. N: number of colonies per site; NACOI-COII: number of individuals with missing COI-COII data, Nall: mean number of alleles; Hnb and Hobs: unbiased expected and observed heterozygos...

Genetic structure of honey bee populations from islands in the Comoros Archipelago, inferred from 14 loci microsatellites. A) STRUCTURE bar plots from K = 2 to 5. All colonies had haplotypes from the COI-COII intergenic region characteristic of the African evolutionary lineage. B) Average likelihood of runs in STRUCTURE L(K) along with number of K...

A) Average likelihood of runs in STRUCTURE L(K) along with number of K clusters for global STRUCTURE based on 4,388 honey bees Comoros Archipelago (Fig 6). B) ΔK, estimator of the optimal number of clusters (K) according to Evanno et al. (58). (TIF)

Relationship among the different genetic clusters computed using DAPC approach on 4,388 samples of the Western honey bee. Colors of the different clusters correspond to the S10 Fig. (TIF)

Introduction -Mango (Mangifera indica L.) is the second most important tropical fruit produced worldwide. In Reunion Island, serious losses are the result of damage caused by Orthops palus (Taylor, 1947) (Heteroptera, Miridae). This bug sucks the sap of mango inflorescences, causing them to dry out. However, little is known about this pest and the...

The honeybee population of the tropical Reunion Island is a genetic admixture of the Apis mellifera unicolor subspecies, originally described in Madagascar, and of European subspecies, mainly A.m. carnica and A. m. ligustica, regularly imported to the island since the late 19th century. We took advantage of this population to study genetic admixing...

Ecological specialization of insects involves the functional and morphological reshaping of olfactory systems. Little is known about the degree to which insect sensitivity to odorant compounds is conserved between genera, tribes, or families. Here we compared the olfactory systems of six tephritid fruit fly species spanning two tribes and the dista...

Molecular species identification using sub-optimal PCR primers can over-estimate species diversity due to co-amplification of nuclear mitochondrial (NUMT) DNA/pseudogenes. For the agriculturally important whitefly Bemisia tabaci cryptic pest species complex, species identification depends primarily on characterisation of the mitochondrial DNA cytoc...

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 geminiviruse...

B. tabaci mtCOI sequences used to construct the phylogeny and haplotype network. Sequences presented were all of 504 bp and represent 587 samples obtained from Central African Republic. Nb: Number of each individual haplotype. (DOCX)

Background: The flea Xenopsylla cheopis (Siphonaptera: Pulicidae) is a vector of plague. Despite this insect's medical importance, especially in Madagascar where plague is endemic, little is known about the organization of its natural populations. We undertook population genetic analyses (i) to determine the spatial genetic structure of X. cheopis...