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Variabilité de la diapause chez les parasitoïdes de pucerons dans le cadre des changements climatiques : implications en lutte biologique

Abstract : Climate changes alter the phenology of organisms, i.e. the succession over time of the elements of their life-cycle. Diapause expression in insects – that is, the developmental arrest allowing survival to seasonal degradations in the biotic and abiotic environment – is particularly affected. This thesis addresses the existence of different environmental factors acting on the seasonal strategies of Aphidius aphid parasitoids. In cereal agro-systems of western France, host and parasitoid communities have changed rapidly over the past decade. Hence, some parasitoid species enter diapause at low levels due to temperature increase, decrease in frost events and the presence of their hosts during winter, which impose selection on diapause induction thresholds. Parasitoids show plastic adjustments of their response to environmental stimuli inducing diapause. They enter diapause at higher proportion if they develop in sexual morphs of aphids (which inform for upcoming limited resources) than in asexual hosts, which underlines the co-evolution of their life-cycles. Transgenerational plasticity is also involved in these responses since maternal competition induces summer diapause in their offspring. Moreover, winter diapause incidence increases after some parasitoid generations experience the same environmental conditions. Local adaptations of parasitoids to new environmental conditions lead to a loss of diapause expression – which involves ecological and physiological costs – to the benefit of adult overwintering strategies. Modifications in species activity-density within aphids-(hyper)parasitoids communities, due to changes in overwintering strategies, could affect food-webs’ stability and alter positively or negatively the efficiency of biological pest control.
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https://tel.archives-ouvertes.fr/tel-01762557
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Submitted on : Tuesday, April 10, 2018 - 11:21:08 AM
Last modification on : Monday, October 19, 2020 - 10:55:57 AM

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  • HAL Id : tel-01762557, version 1

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Kévin Tougeron. Variabilité de la diapause chez les parasitoïdes de pucerons dans le cadre des changements climatiques : implications en lutte biologique. Sciences agricoles. Université Rennes 1, 2017. Français. ⟨NNT : 2017REN1B030⟩. ⟨tel-01762557⟩

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