Traitement en barrière avec Metarhizium acridum : exposition expérimentale des larves du criquet pelerin

Compte tenu de sa rémanence dans l’environnement, l'utilisation de l’entomopathogène Metarhizium acridum en traitement en barrière contre les larves du Criquet pèlerin est une nouvelle option pour réduire le coût de la lutte. De jeunes larves de 5e stade ont été exposées à de la végétation traitée dans des cages moustiquaires 6, 24 et 48 après le traitement pour simuler le passage des bandes larvaires d'une barrière à l'autre. Les cages sont placées sur les barrières traitées à des distances de 15, 25, 40 et 70m de la passe de traitement. Après deux semaines de suivi, les taux de mortalité des larves exposées à une seule barrière étaient de 53 à 69 % après 6 h et de 50 à 70 % après 24 h avec respectivement 23 à 41 % et 27 à 35 % de sporulation. Cependant, le déplacement des larves vers une deuxième barrière a significativement amélioré l’efficacité du biopesticide. Après 48 h d’exposition (24 h sur une première barrière puis 24 h sur une deuxième), les taux de mortalité étaient entre 52 et 89 % avec une sporulation de 37 à 75 %. Il parait clair que le déplacement des larves vers une deuxième barrière (48h d’exposition) est nécessaire pour une meilleure efficacité. Cette amélioration de l’efficacité pourrait être attribuée à un effet d’accumulation des conidies lors du passage des larves d’une barrière à une autre. A cet effet, il est recommandé de réaliser des études en conditions opérationnelles pour évaluer l’efficacité du M. acridum sur des bandes larvaires en traitement en barrière

Structural basis for hijacking of cellular LxxLL motifs by papillomavirus E6 oncoproteins

E6 viral oncoproteins are key players in epithelial tumors induced by papillomaviruses in vertebrates, including cervical cancer in humans. E6 proteins target many host proteins by specifically interacting with acidic LxxLL motifs. We solved the crystal structures of bovine (BPV1) and human (HPV16) papillomavirus E6 proteins bound to LxxLL peptides from the focal adhesion protein paxillin and the ubiquitin ligase E6AP, respectively. In both E6 proteins, two zinc domains and a linker helix form a basic-hydrophobic pocket, which captures helical LxxLL motifs in a way compatible with other interaction modes. Mutational inactivation of the LxxLL binding pocket disrupts the oncogenic activities of both E6 proteins. This work reveals the structural basis of both the multifunctionality and the oncogenicity of E6 proteins

Prévention des invasions de criquets pèlerins : analyse socio-technique d'un dispositif de gestion du risque

National audienceDe par leur nature et leurs conséquences, les invasions de criquet pèlerin sont des phénomènes incertains, dynamiques et complexes auxquels des acteurs variés s'attachent à faire face. Les gestionnaires des invasions acridiennes établissent et "appareillent" des stratégies de surveillance et de lutte dont les résultats sont souvent difficiles à apprécier du fait de l'existence de situations de crise suivies de longs moments de rémission pendant lesquels les efforts de veille et de lutte peuvent parfois sembler superflus. L'invasion de 2003-2005 en Afrique de l'Ouest a réactivé le débat sur l'importance économique de cet insecte, sur l'évaluation des opérations de lutte préventive et curative, ainsi que sur les solutions stratégiques réalistes aux problèmes posés par ce ravageur. Cet article rend compte d'un travail de terrain réalisé en Mauritanie. Il tente de décrire et de comprendre les défaillances du dispositif de lutte préventive qui ont conduit à cette dernière invasion. Notre travail de compréhension de la mise en gestion passe ici par une lecture diachronique basée sur l'analyse des documents qui forment la traçabilité d'un tel processus. Nous verrons comment cette analyse nous permet de formuler quelques pistes de réflexion sur les défaillances du dispositif de prévention contre les invasions de criquet pèlerin et sur les propositions que cela invite à formuler pour y faire face

Acceptability of focused antenatal care by pregnant Nigerian women and factors influencing it

Context: In 2002, the World Health Organization (WHO) proposed "Focused Antenatal Care (FANC)"model for developing countries and it is aimed at addressing some of the challenges associated with the traditional model of antenatal care and to improve the quality of antenatal care services rendered. Despite its wide publicity, most teaching hospitals in Nigeria still practice the traditional ANC model, notwithstanding the high level of awareness of the tenet ofFANC among resident doctors.Objective: This study aimed at assessing the acceptability of this new model by Nigerian pregnant women.Methodology: This was a questionnaire-based cross-sectional study conducted at the antenatal clinic at thc Lagos University Teaching Hospital (LUTH). A total of 410 consenting pregnant women at varying gestational ages were recruited for this study. Data collected was analyzed using Epi Info statistical software.Results : The mean age ± S.D. of the subjects was 31.2 ± 4.3 years, with over half of the patients living close to the hospital (56.4%). The mean gestational age± S.D. at booking was 16.0± 6.3 weeks and 54.5% were high risk pregnancy. Over a third (35.1 %) of the women had missed at least 1 - 3 visits. A greater proportion (56.1%) of the pregnant women studied preferred the new model, FANC, while 42.4% indicated preference for the traditional model. The main reason for preferring FANC is convenience (92.2% of respondents). The main reasons for rejecting FANC are that complications can arise in pregnancy at anytime (71.3%) and 4 visits were adjudged to be inadequate (43.7%). Factors influencing thc acceptability of FANC by Nigerian pregnant women were age (p - 0.00(0). tribe (p '" 0.0487), proximity to the hospital (0.0088) and parity (p - 0.0006).Conclusion: Many parturient are ready to accept FANC if given the opportunities. It should thus be offered to highly motivated women especially in urban cities in Nigeria where many educated women reside, but education on birth preparedness and complication readiness needs to be emphasized.Key words: acceptability focused antenatal care, influencing factors

A general model of the thermal constraints on the world’s most destructive locust, Schistocerca gregaria

International audienceAll terrestrial ectotherms are constrained to some degree by their thermal environment and the extent to which they can behaviorally buffer variable thermal conditions. New biophysical modeling methods (NicheMapR) allow the calculation of the body temperature of thermoregulating animals anywhere in the world from first principles, but require detailed observational data for parameterization and testing. Here we describe the thermoregulatory biology of marching bands of the desert locust, Schistocerca gregaria, in the Sahara Desert of Mauritania where extreme heat and strong diurnal fluctuations are a major constraint on activity and physiological processes. Using a thermal infrared camera in the field, we showed that gregarious nymphs altered the microhabitats they used, as well as postural thermoregulatory behaviors, to maintain relatively high body temperature (nearly 40 degrees C). Field and laboratory experiments demonstrated that the preferred body temperature accelerated digestive rates. Migratory bands frequently left foraging sites with full guts before consuming all vegetation and moved to another habitat before emptying their foregut. Thus, the repertoire for behavioral thermoregulation in the desert locust strongly facilitates foraging and digestion rates, which may accelerate developmental rates and increase survival. We used our data to successfully parameterize a general biophysical model of thermoregulatory behavior that could capture hourly body temperature and activity at our remote site using globally available environmental forcing data. This modeling approach provides a stronger basis for forecasting thermal constraints on locust outbreaks under current and future climates

Laboratory populations as a resource for understanding the relationship between genotypes and phenotypes: A global case study in locusts

status: publishe

Laboratory populations as a resource for understanding the relationship between genotypes and phenotypes: A global case study in locusts

Publisher summary : The expression of phenotypic plasticity is widespread in insects. One of the most extraordinary and economically devastating examples of phenotypic plasticity is found in locusts. In contrast to typical grasshoppers, locust species express an extreme form of density-dependent phenotypic plasticity known as "phase polyphenism." Environmental factors such as temperature, photoperiod, resource availability and population density, are known to affect the development of a myriad of phenotypic traits that have consequences for individual performance, ecology, life-history, fitness and subsequent evolution. Given their diversity of responses and amenability to experimental manipulation and rearing in the lab, insects continue to play an important role as model organisms in empirical analyses of the fundamental relationships between genotypes and phenotypes in animals. Critical conclusions and recommendations from the analysis of recent laboratory stocks, findings that are broadly applicable across taxa to any research program rearing organisms in the lab, are also given in the chapte