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Intraspecific maternal competition in insect parasitoids induces summer diapause in insect parasitoids

Insect Science 2018年第6期25卷 1080-1088页

作者： kévin tougeron George Hraoui Cécile Le Lann Joan van Baaren Jacques Brodeur UMR-CNRS 6553Ecobio Universitéde Rennes 1RennesFrance Université Bretagne Loire Cité InternationaleRennesFrance Département de Sciences Biologiques Institut de Recherche en Biologie VegétaleUniversitéde MontréalMontréalCanada

Organisms often live in unpredictable environments and have to adopt life history strategies that optimize their fitness under these *** to bet-hedging theory,individuals can reduce variation in fitness outcomes by investing in different strategies at the same *** arthropods,facultative summer diapause enables survival during dry and hot periods of the year,and can be triggered by a decrease in resource abundance. However,the effect of resource depletion on diapause induction has never been disentangled from the effect of the perception of the presence of *** two solitary parasitoid species of cereal aphids as a model system,Aphidius avenae (Haliday)and Aphidius rhopalosiphi (De Stefani-Perez)(Hymenoptera:Braconidae),we tested whether (i)low absolute host density and/or (ii)high levels of parasitoid females'competition lead to maternal-induced summer diapause in parasitoid *** summer-like climatic conditions,emerging parasitoid females were (i)reared alone and exposed to different host densities (from 5 to 130 aphids),or (ii)reared together with competing females (from 2 to 20 females)and then exposed individually to 50 *** both parasitoid species, low aphid densities did not induce summer ***,the incidence of summer diapause increased up to a maximum of 11% with increasing levels of competition expe rienced by female *** than 60% of the females produced both diapausing and nondiapausing offspring after being kept at the two highest competition densities. Such a "spreading-the-risk"strategy has likely evolved to optimize parasitoid fitness by preventing the following generation from exposure to low populations of suitable hosts and high mortality from *** results provide the first experimental evidence of direct maternal competition-induced diapause in insects,and may change the way we apprehend the evolution of arthropod seasonal ecology,by considering intraspecific c

关键词： aestivation bet-hedging host density intraspecific competition superparasitism

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Transgenerational phenotypic plasticity of diapause induction and related fitness cost in a commercial strain of the parasitoid Aphidius ervi Haliday

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Insect Science 2021年第3期28卷 780-792页

作者： Muhammad Mubashir Saeed kevin tougeron Abu Bakar Muhammad Raza Muhammad Afzal Anjum Aqueel Guillaume Jean Le Goff Frangois Renoz Jennifer Pirotte Thierry Hance Department of Entomology University College of AgricultureUniversity of SargodhaSargodhaPakistan Earth and Life Institute Biodiversity Research CentreUniversite catholique de LouvainLouvain-la-Neuve1348Belgium

Diapause is an adaptation that insects have evolved to synchronize their life cycle with that of seasonal climatic changes and resources ***,cues for its induction are not always clear and,in some cases,a maternal effect may be *** the population level,just a part of the individuals may exhibit diapause with important consequences in terms of winter ***,clear indicators of diapause state are difficult to *** induction was thus investigated in the aphid parasitoid species Aphidius ervi Haliday(Hymenoptera:Braconidae)developing in the aphid Sitobion avenae(Hemiptera:Aphididae)at four crossed photothermal regimes(16℃and 8℃,16:8 h L:D and 8:16 h L:D),and during 2 successive *** analyzed the reliability of changes in mummy color to assess for the diapausing state compared to dissections,and we measured parasitoid morphological and physiological *** observed that the proportion of dark brown mummies increased after one generation under low photothermal regime compared to other *** diapause was recorded at 16℃,16:8 h L:D,while we observed 16.2%and 67.5%diapause incidence at 8℃,8:16 h L:D,at 1st and 2nd generation,*** induction is thus increased by short day-length conditions and low temperatures as well as by maternal *** parasitoid life-history traits(weight,size,fat content,water content,egg-load,and longevity)were affected by the photothermal regime and/or the *** results raise new questions on the environmental thresholds needed to induce diapause and on survival and adaptation potential of commercially available parasitoid strains in different environments.

关键词： dormancy life-history traits mummy color photothermal regimes transgenerational plasticity

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The effect of landscape complexity and microclimate on the thermal tolerance of a pest insect

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Insect Science 2018年第5期25卷 905-915页

作者： Lucy Alford kevin tougeron Jean-Sebastien Pierre Francoise Burel Joan van Baaren UMR 6553 ECOBIO Centre National de la Recherche Scientitique Universite de Rennes I Rennes Cedex France Departement de Sciences Biologiques Insfitut de Recherche en Biologie Vegetale Universite de Montreal Montreal QC Canada Universite Europeenne de Bretagne (UEB) Rennes France

Landscape changes are known to exacerbate the impacts of climate change. As such, understanding the combined effect of climate and landscape on agroecosystems is vital if we are to maintain the fimction of agroecosystems. This study aimed to elucidate the effects of agricultural landscape complexity on the microclimate and thermal tolerance of an aphid pest to better understand how landscape and climate may interact to affect the thermal tolerance of pest species within the context of global climate change. Meteo- rological data were measured at the landscape level, and cereal aphids （Sitobion avenae, Metopolophium dirhodum and Rhopalosiphum padi） sampled, from contrasting landscapes （simple and complex） in winter 2013/2014 and spring 2014 in cereal fields of Brittany, France. Aphids were returned to the laboratory and the effect of landscape of origin on aphid cold tolerance （as determined by CTmin） was investigated. Results revealed that local landscape complexity significantly affected microclimate, with simple homogenous landscapes being on average warmer, but with greater temperature variation. Landscape complexity was shown to impact aphid cold tolerance, with aphids from complex land- scapes being more cold tolerant than those from simple landscapes in both winter and spring, but with differences among species. This study highlights that future changes to land use could have implications for the thermal tolerance and adaptability of insects. Fur- thermore, not all insect species respond in a similar way to microhabitat and microclimate, which could disrupt important predator-prey relationships and the ecosystem service they provide.

关键词： agroecosystems biological control cereal aphids climate change coldtolerance landscape ecology

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Anti program death-1/anti program death-ligand 1 in digestive cancers

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World Journal of Gastrointestinal Oncology 2015年第8期7卷 95-101页

作者： Eléonore de Guillebon Pauline Roussille Eric Frouin David tougeron Medical Oncology Department Poitiers University Hospital Radiation Oncology Department Poitiers University Hospital Pathology Department Poitiers University Hospital David tougeron Laboratory Inflammation Tissus Epithéliaux et Cytokines EA 4331 Poitiers University Gastroenterology Department Poitiers University Hospital

Human tumors tend to activate the immune system regulatory checkpoints as a means of escaping immunosurveillance. For instance, interaction between program death-1(PD-1) and program death-ligand 1(PD-L1) will lead the activated T cell to a state of anergy. PD-L1 is upregulated on a wide range of cancer cells. Anti-PD-1 and anti-PD-L1 monoclonal antibodies(m Abs), called immune checkpoint inhibitors(ICIs), have consequently been designed to restore T cell activity. Accumulating data are in favor of an association between PD-L1 expression in tumors and response to treatment. A PD-L1 expression is present in 30% to 50% of digestive cancers. Multiple anti-PD-1(nivolumab, pembrolizumab) and anti-PD-L1 m Abs(MPDL3280A, Medi4736) are under evaluation in digestive cancers. Preliminary results in metastatic gastric cancer with pembrolizumab are highly promising and phase Ⅱ will start soon. In metastatic colorectal cancer(CRC), a phase Ⅲ trial of MPDL3280 A as maintenance therapy will shortly be initiated. Trials are also ongoing in metastatic CRC with high immune T cell infiltration(i.e., microsatellite instability). Major challenges are ahead in order to determine how, when and for which patients we should use these ICIs. New radiologic criteria to evaluate tumor response to ICIs are awaiting prospective validation. The optimal therapeutic sequence and association with cytotoxic chemotherapy needs to be established. Finally, biomarker identification will be crucial to selection ofpatients likely to benefit from ICIs.

关键词： Program death-1 Program death-ligand 1 Antibody Digestive cancer

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