Research Interests:
National audienceCet ouvrage présente les grandes fonctions des insectes, leur fonctionnement individuel et collectif, leurs interactions plus ou moins intimes avec les composantes de l’écosystème, en particulier les plantes, en... more
National audienceCet ouvrage présente les grandes fonctions des insectes, leur fonctionnement individuel et collectif, leurs interactions plus ou moins intimes avec les composantes de l’écosystème, en particulier les plantes, en s’appuyant sur l’histoire évolutive à l’origine de ces interactions. Il décrit les multiples applications des recherches sur les insectes pour l’agriculture
Research Interests:
Research Interests:
Foraging insect parasitoids use specific chemical cues to discriminate between host and non-host species. Several compounds have been identified in "host location and acceptance." However, nothing is known about the molecular... more
Foraging insect parasitoids use specific chemical cues to discriminate between host and non-host species. Several compounds have been identified in "host location and acceptance." However, nothing is known about the molecular variations in these compounds that could account for host-range differences between parasitoid species. In a previous study, it was shown that during the host-finding process, contact between the braconid Cotesia flavipes and its host is crucial, and that alpha-amylase of oral secretions from the host plays a key role for host acceptance and oviposition by the parasitoid. The present study sought to establish whether the variations in this enzyme could explain specific host recognition in different host-parasitoid associations. Different species and populations of the C. flavipes complex specialized on graminaceous lepidopteran stemborers were used. Electrophoresis of alpha-amylase revealed different isoforms that mediate the parasitoid's oviposit...
Research Interests:
Busseola fusca (Lepidoptera: Noctuidae) is an important pest of maize and sorghum in sub-Saharan Africa. One century after its first description by Fuller in 1901, inaccurate information based on earlier reports are still propagated on... more
Busseola fusca (Lepidoptera: Noctuidae) is an important pest of maize and sorghum in sub-Saharan Africa. One century after its first description by Fuller in 1901, inaccurate information based on earlier reports are still propagated on its distribution (e.g., absent from the lower altitudes in East Africa) and host plant range (e.g., feeding on a large range of wild grass species). This review provides updated information on the biology, distribution and genetics of B. fusca with emphasis on insect-plant interactions. Related to this, new avenues of stem borer management are proposed
Research Interests: Reproduction and Mais
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Chapitre 23International audienc
Research Interests:
Research Interests:
Research Interests:
A previous study on the population dynamics of the cassava mealybug, Phenacoccus manihoti (Matile-Ferrero), on cassava has shown that populations increase during the dry season. The aim of the present studies was to determine whether... more
A previous study on the population dynamics of the cassava mealybug, Phenacoccus manihoti (Matile-Ferrero), on cassava has shown that populations increase during the dry season. The aim of the present studies was to determine whether these important changes in the pest population observed throughout the seasons in the field in the Congo, could be correlated with seasonal variations in the level of secondary compounds in the phloem, implicated in cassava plant resistance to P. manihoti. Our results showed that cassava was in drought stress conditions during the dry season (foliar area decreased). The combination of infestation and dry stress factors was clearly visible during the dry season. In fact, the decrease in leaf water potential together with infestation by P. manihoti was clearly observed at the end of the rainy season and during the dry season. The levels of the secondary compounds, rutin (an unfavourable substance to P. manihoti) decreased in the less resistant genotype, a...
Research Interests:
Research Interests:
The noctuid stem borer Busseola fusca is an important pest of maize and sorghum in Sub-Saharan Africa. The presence of this species occurred mostly on cultivated than on wild habitats. Busseola fusca is oligophagous having a narrow range... more
The noctuid stem borer Busseola fusca is an important pest of maize and sorghum in Sub-Saharan Africa. The presence of this species occurred mostly on cultivated than on wild habitats. Busseola fusca is oligophagous having a narrow range of a wild grass species. This might be due, in part, to differences in silicon (Si) content in plant tissues between cultivated and wild grasses. In the present study, we have tested this hypothesis by studying the survival and the relative growth rate (RGR) expressed as daily weight gains of B. fusca larvae on maize and six wild host plants, mostly present in the natural habitat where B. fusca occurred, and correlated with their Si contents. Survival and RGR of B. fusca larvae were considerably higher on maize and wild sorghum than on the other grass species, and they were negatively related to plant Si content. This was corroborated with results on RGR from artificial diets amended with increasing levels of Si. In addition, if Si was added to maiz...
Research Interests:
Research Interests:
Research Interests:
Hymenopterans are haplodiploids and unlike most other Arthropods they do not possess sexual chromosomes. Sex determination typically happens via the ploidy of individuals: haploids become males and diploids become females. Arrhenotoky is... more
Hymenopterans are haplodiploids and unlike most other Arthropods they do not possess sexual chromosomes. Sex determination typically happens via the ploidy of individuals: haploids become males and diploids become females. Arrhenotoky is believed to be the ancestral reproduction mode in Hymenopterans, with haploid males produced parthenogenetically, and diploid females produced sexually. However, a number of transitions towards thelytoky (diploid females produced parthenogenetically) have appeared in Hymenopterans, and in most cases populations or species are either totally arrhenotokous or totally thelytokous. Here we present the case of Cotesia typhae (Fernandez-Triana), a Braconidae that produces parthenogenetic females at a low frequency. The phenotyping of two laboratory strains and one natural population showed that this frequency is variable, and that this rare thelytokous phenomenon also happens in the wild. Moreover, mated females from one of the laboratory strains produce ...
Research Interests:
This dataset corresponds to climate data for the year 2020 at ICIPE, Nairobi, Kenya. The data includes temperature, relative humidity, atmospheric pressure in three separate CSV files with approximately one measurement every minute. The... more
This dataset corresponds to climate data for the year 2020 at ICIPE, Nairobi, Kenya. The data includes temperature, relative humidity, atmospheric pressure in three separate CSV files with approximately one measurement every minute. The first column indicates the date and time in UTC and the second column the measurement made (column names are visible in the header). The measurements were made using a BME680 type sensor calibrated with a DS18B20 temperature probe, and connected to a Raspberry Pi. The dataset includes an R script to read the data and basic graphical visualizations. More information can be found here: https://pi2p.ird.fr/
Research Interests:
Exotic invasive insect herbivores have the potential to interfere with existing herbivore-natural enemy interactions in new environments. Fall armyworm (FAW), Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctuidae), is a new invasive... more
Exotic invasive insect herbivores have the potential to interfere with existing herbivore-natural enemy interactions in new environments. Fall armyworm (FAW), Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctuidae), is a new invasive pest in maize fields in Africa. Understanding the acceptability and suitability of FAW to existing maize stemborer-parasitoid interactions is the first step in elucidating the impact that this exotic insect pest can have on the existing natural enemies used in biological control of maize stemborers in Kenya. The most commonly used larval parasitoids for biological control programs against maize stemborer communities in East Africa are Cotesia flavipes Cameron (Hymenoptera: Braconidae) and two populations of the native Cotesia sesamiae (Cs-Inland and Cs-Coast) Cameron (Hymenoptera: Braconidae). All these parasitoid species attacked FAW larvae but none yielded offspring, although they induced high non-reproductive host mortality when compared to natural mortality. Furthermore, the parasitoids that inserted their ovipositor into FAW larvae exhibited no significant preference between FAW larvae and their respective stemborer hosts under dual-choice bioassays. In olfactometer bioassays, the parasitoids were more attracted to plants infested by FAW than uninfested plants and even showed a marked preference for the odours of plants infested by FAW over those of plants infested by their natural host counterparts. This study illustrates that exotic pests, such as FAW, can impact existing stemborer-parasitoid interactions associated with maize, even if they cannot be used as hosts by parasitoids associated with these stemborers. Although additional studies are needed, FAW might therefore have a negative impact on stemborer biological control existing before its invasion.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Comment, depuis plusieurs decennies, la recherche scientifique contribue-t-elle au developpement des pays du Sud ? A travers plus de 100 succes emblematiques de la recherche en partenariat, cet ouvrage nous plonge au coeur des grandes... more
Comment, depuis plusieurs decennies, la recherche scientifique contribue-t-elle au developpement des pays du Sud ? A travers plus de 100 succes emblematiques de la recherche en partenariat, cet ouvrage nous plonge au coeur des grandes questions de developpement : oeuvrer pour des societes plus justes, lutter contre les maladies, faire face aux risques naturels, mettre en place une agriculture durable garantissant la securite alimentaire, preserver la biodiversite, partager les savoirs... Il montre ainsi comment la recherche contribue a l'amelioration des conditions de vie et a la preservation de l'environnement dans les pays en developpement, en soulignant le role de la science pour repondre aux defis du monde actuel et a venir. Compose de textes courts, didactiques et richement illustres, il s'adresse a tous les publics.
Research Interests: Political Science and IRD
Research Interests:
Research Interests:
Research Interests:
Cette etude demontre l'apport de la biologie cellulaire a la comprehension des mecanismes de resistance des plantes aux parasites. Les techniques modernes de la cytologie moleculaire permettent de suivre le devenir d'une molecule... more
Cette etude demontre l'apport de la biologie cellulaire a la comprehension des mecanismes de resistance des plantes aux parasites. Les techniques modernes de la cytologie moleculaire permettent de suivre le devenir d'une molecule au cours d'une interaction, d'en preciser la distribution a l'echelle des tissus et de la cellule, et de la visualiser par rapport aux sites d'infection et de localisation du parasite. Les recherches ont ete realisees sur les modeles suivants : hevea-champignon, manioc-bacterie, manioc-cochenille, cotonnier-bacterie et bananier-nematode
Climate change (CC) is expected to significantly affect biodiversity and ecosystem services. Adverse impacts from CC in the Global South are likely to be exacerbated by limited capacities to take adequate adaptation measures and existing... more
Climate change (CC) is expected to significantly affect biodiversity and ecosystem services. Adverse impacts from CC in the Global South are likely to be exacerbated by limited capacities to take adequate adaptation measures and existing developmental challenges. Insect pests today are already causing considerable yield losses in agricultural crop production in East Africa. Studies have shown that insects are strongly responding to CC by proliferation, shift in distribution or by altering their phenology, which is why an impact on agriculture can also be expected. Biological control (BC) has been proposed as an alternative measure to sustainably contain insect pests but few studies predict its efficacy under future CC. Using the species distribution modelling approach Maxent, we predict the current and future distribution of three important lepidopteran stem borer pests of maize in eastern Africa, i.e., Busseola fusca (Fuller, 1901), Chilo partellus (Swinhoe, 1885) and Sesamia calam...
Research Interests:
La vision chez Les insectes En 440 millions d'années d' évolution, la nature a créé autant de formes de vision que de types d'yeux, la vision de chaque espèce étant adaptée à son mode de vie. Il faut des yeux pour fuir, pour... more
La vision chez Les insectes En 440 millions d'années d' évolution, la nature a créé autant de formes de vision que de types d'yeux, la vision de chaque espèce étant adaptée à son mode de vie. Il faut des yeux pour fuir, pour tuer et se déplacer. De par les richesses des inter-actions qu' entretiennent les insectes avec leur environnement, leurs organes sensoriels sont très complexes, et c' est particulièrement vrai pour ceux liés à la vision. La lumière est perçue par différents types de récepteurs. Dans la plupart des cas, ces récep-teurs sont regroupés en organe sur la tête pour constituer une rétine recouverte d'une lentille chitineuse transparente, la cornée. Les insectes possèdent deux types d' organes visuels, simples ou composés (Bernays et Chapman, 1994 ; Chapman, 1998 ; Daly et al., 1998 ; Dethier, 1963). Certaines espèces possèdent simplement des récepteurs épidermiques et, dans d'autres cas, la lumière a un effet direct sur les cellules du ...
Two encyrtid species, Acerophagus coccois and Aenasius vexans, parasitoids of the cassava mealybug Phenacoccus herreni use a contact kairomone from the body surface of their host as a host-location stimulant. The kairomone was synthesized... more
Two encyrtid species, Acerophagus coccois and Aenasius vexans, parasitoids of the cassava mealybug Phenacoccus herreni use a contact kairomone from the body surface of their host as a host-location stimulant. The kairomone was synthesized and identified as O-caffeoylserine based on a combination of chromatographic methods. The synthetic compound was determined to be active.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Figure 8 from: Kaiser L, Fernandez-Triana J, Capdevielle-Dulac C, Chantre C, Bodet M, Kaoula F, Benoist R, Calatayud P, Dupas S, Herniou EA, Jeannette R, Obonyo J, Silvain JF, Le Ru B (2017) Systematics and biology of Cotesia typhae sp. n. (Hymenoptera, Braconidae, Microgastrinae), a potential bi...more
Originaire des régions tropicales d'Amérique du Sud, la cochenille du manioc fut introduite accidentellement sur le continent africain, au début des années 1970, probablement partir de boutures contaminées. Elle est signalte pour la... more
Originaire des régions tropicales d'Amérique du Sud, la cochenille du manioc fut introduite accidentellement sur le continent africain, au début des années 1970, probablement partir de boutures contaminées. Elle est signalte pour la première fois au Congo et au Zaïre, en 1973. En 1990, ce ravageur s'est propagé à l'ensemble de la zone de culture du manioc en Afrique, du Sénégal au Zimbabwé, ob il occasionne en moyenne des pertes de récoltes en tubercules évaluées B 30%, mettant en péril l'alimentation de base de près de 200 millions d'habitants. Devant l'ampleur des pertes, les instances nationales et internationales ont développé, B la fin des années 1970, des programmes de recherches visant I mettre au point des méthodes de lutte contre ce ravageur. Au Congo, le programme de recherche sur la cochenille du manioc fut entrepris dès 1978. Différentes méthodes de lutte s'offraient aux investigations de la recherche. D'emblée la lutte chimique
Research Interests:
Research Interests:
Research Interests:
Studies on pathogenic agents of cultivated plants are generally organised on a binomial basis with examination of a host plant and specific parasites or pests. As cassava in Africa has few important pests and they display a limited range... more
Studies on pathogenic agents of cultivated plants are generally organised on a binomial basis with examination of a host plant and specific parasites or pests. As cassava in Africa has few important pests and they display a limited range of biological features and relations with the host, it was feasible for ORSTOM (L'Institutfrancaise de recherche scientifique pour le developpement en cooperaton) researchers to study each of them over a period of 25 years in Cote d'lvoire, Congo and Togo and such work is currently in progress in Benin and France. The diseases and pests concerned are African cassava mosaic disease and its whitefly vector ( Bemisia tahaci ), cassava bacterial blight caused by Xanthomonas campestris pv manihotis , cassava mealybug ( Phenacoccus manihoti ), and cassava green mite ( Mononychelus progresivus ). Research initially concerned only specific cassava-pathogen or cassava-pest combinations, without attention being paid to the system as a whole, despite o...