Efeitos diretos e indiretos de características de plantas sobre a similaridade na composição de insetos herbívoros e parasitoides associados à Asteraceae
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2018-03-15
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Universidade Federal de Goiás
Resumo
Understanding how interactions between trophic levels structure species composition is one of
the main goals of ecological studies. Mechanisms that explain the compositional structure of
parasitoid insects usually neglect the direct and indirect effects of plants’ characteristics, which
can also determine the compositional structure of their host herbivore insects. In this context, our
goal was to evaluate how plants’ characteristics (abundance, floral phenology, and phylogenetic
distance) and herbivores’ compositional similarity determine parasitoids’ compositional
similarity. As study system, we used Asteraceae species, flower-head feeding insects, and
parasitoids. Using path analysis, we considered parasitoids and herbivores’ similarities, in
qualitative (Sørensen similarity), quantitative (Bray-Curtis similarity), and phylogenetic
proximity (taxonomic Sørensen similarity) terms. In general, we demonstrated that herbivores’
similarity is the major predictor of parasitoids’ similarity. Even though the effects of plants’
characteristics explained the smallest part of the variation in parasitoids’ similarity, these
characteristics had inconsistent relative importance among the similarity indexes used here. Thus,
our results indicate that although plant species constitute a potential additional barrier for the
parasitoids of endophagous herbivores to find their insect hosts, herbivore parasitoids in flower
heads of Asteraceae do not see the plant species in this way. The parasitoids respond mainly to
the compositional variation of their insect hosts in the plant species that the latter consume.
Therefore, we show how the composition of the upper trophic levels in this tri-trophic system is
structured directly and indirectly by antagonistic interactions.
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ALVARENGA, V. S. Efeitos diretos e indiretos de características de plantas sobre a similaridade na composição de insetos herbívoros e parasitoides associados à Asteraceae. 2018. 47 f. Dissertação (Mestrado em Ecologia e Evolução) - Universidade Federal de Goiás, Goiânia, 2018.