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Diversité des communautés d’arthropodes et efficacité de la lutte biologique contre les insectes ravageurs

Abstract : Understanding of driving forces that affect diversity in herbivorous insect communities figures prominently in ecological research, and is necessary for integrated pest management, because some herbivorous insect can become crop pests. Natural enemies and environmental variables are among factors that structure herbivorous insect communities. While natural enemies regulate herbivorous insects, environmental variables affect their diversity and their spatial distribution. The main goal of this thesis was to understand effects of landscape features on diversity of herbivorous thrips communities along elevational gradients in Reunion, and to investigate effects of natural enemy diversity in biological control of pest thrips. In first study, thrips were sampled along replicated elevational gradients, and at each sampling site, landscape features and abiotic variables were estimated within buffers surrounding the site. Study has shown that the greatest diversity of thrips in Reunion is concentrated at lower elevation, although habitats situated in these localities are highly degraded. Thrips diversity was not affected by fragmentation but landscape heterogeneity and habitat amount interacted to affect positively thrips diversity.In second study, we manipulated communities composed of two pest thrips Thrips parvispinus and Frankliniella occidentalis, and two predatory mites Amblyseius swirskii and Proprioseiopis mexicanus. These communities were in cages and were established in greenhouse. Study has shown that both predators are better than one in thrips regulation. That confirms the necessity to maintain biodiversity at the upper trophic level for herbivore control. Moreover, this study revealed that despite intraguild predation, predators would have coexisted because of competition-colonization trade-off.
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Submitted on : Friday, October 16, 2020 - 1:01:33 AM
Last modification on : Friday, October 16, 2020 - 3:39:20 AM


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Niry Tiana Dianzinga. Diversité des communautés d’arthropodes et efficacité de la lutte biologique contre les insectes ravageurs. Biologie animale. Université de la Réunion, 2020. Français. ⟨NNT : 2020LARE0006⟩. ⟨tel-02968586⟩



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