While pollinators and leaf herbivores have been a focus of research for decades, floral antagonists have been studied significantly less. Since floral antagonists can be as common as leaf herbivores and have strong impacts on plant reproduction, it is important to understand the role of floral antagonists in the ecology and evolution of flowers. I conducted four experiments to better understand the relationship between plants, floral traits, floral antagonists, and other plant-insect interactions. First, I manipulated resources (light and soil nutrients) that are known to have impacts on plants and floral traits to test how they affect floral antagonists and other plant-insect interactions. Plentiful resources increased the proportion of floral antagonists to visit flowers, but also increase tolerance of floral antagonists. Second, I manipulated flower bud gallers, a species-specific floral herbivore that destroys flowers, to test how it affected other plant-insect interactions, floral traits, and plant reproduction. Plants with flower bud gallers tended to have more pollinator visits, but this effect is due to a shared preference by gallers and pollinators for similar plants. Third, I manipulated florivory to examine how it affects subsequent plant-arthropod interactions, floral traits, and plant reproduction. Florivory had systemic effects on other plant-insect interactions, including leaf herbivores, and shifted the plant mating system towards more selfing. Additionally, I tested how several floral antagonists respond to floral attractive and defense traits to understand which floral traits are important in mediating antagonisms. Finally, I manipulated florivory, pollination, and nectar robbing to test for effects of multiple floral interactions on subsequent plant-insect interactions, floral traits, and plant reproduction. There were significant many-way interactions between the three treatments on subsequent plant-insect interactions and reproduction, indicating that the effect of one interaction depends on what other interactions are present. Understanding the role that floral antagonists play in plant ecology can help scientists determine which interactions are most important, and may help determine why some floral traits exist in their current state. Together, this work represents some of the most comprehensive research on the community consequences of floral antagonists, as well as the interplay between floral traits and floral interactions.

A tribo Asphondyliini, pertencente à família Cecidomyiidae, conta com 521 espécies divididas em 44 gêneros com distribuição cosmopolita. Os Asphondyliini estão inseridos na subfamília Cecidomyiinae, que é a maior subfamília em número de espécies, 5100, e se encontra dividida em quatro supertribos: Brachineuridi, Stromatosematidi, Cecidomyiidi e Lasiopteridi. As larvas de Cecidomyiinae possuem hábito micetófago, predador e galhador, sendo que este último aparece nas supertribos Cecidomyiidi e Lasiopteridi. Os galhadores são os organismos indutores responsáveis por malformações de porções dos tecidos ou órgãos das plantas, conhecidas como galhas. A relação entre os insetos galhadores e suas plantas hospedeiras é de alta especificidade e devido a isso, para as espécies descritas, é possível identificá-las pelo seu tipo de galha induzida no hospedeiro. O gênero Bruggmanniella Tavares, 1909, possui 11 espécies com distribuição majoritária na região Neotropical (oito espécies) e representantes descritos para as regiões Neártica (uma espécie) e Oriental (duas espécies). Neste trabalho foi realizada a primeira análise cladística para compreensão da relação de parentesco entre as espécies de Bruggmanniela, a descrição de uma espécie nova do Estado de São Paulo, Brasil, além da atualização da chave de identificação das espécies de Bruggmanniella. Na análise cladística foram levantados 56 caracteres morfológicos para 26 táxons terminais. Entre esses, 15 pertencem ao grupo-externo e 11 ao interno. A análise utilizando busca heurística de pesos iguais resultou em uma única árvore mais parcimoniosa com comprimento igual a 148 passos (IC=0.443 e IR=0.565) e a de busca por pesagem implícita também gerou uma única árvore com 149 passos (IC=0.440 e IR=0.561). O gênero Bruggmanniella tem sua monofilia suportada principalmente pela ausência do espessamento da margem cefálica da pupa. B. byrsonimae ainda possue posicionamento incerto por falta de conhecimenro do estágio larval. As duas espécies orientais descritas originalmente em Bruggmanniella, B. actinodaphnes e B. cinnamomi, posicionaram-se no ramo do grupo-irmão Pseudasphondylia, ensejando a proposição de duas novas combinações: P. actinodaphnes comb. nov e P. cinnamomi comb. nov. Apresentamos ainda, uma discussão acerca da distribuição geográfica das espécies de Bruggmanniella e Pseudasphondylia e a ocupação dos hospedeiros. / The tribe Asphondyliini, belonging to the family Cecidomyiidae, has 521 species divided into 44 genera with cosmopolitan distribution. The Asphondyliini are included in the subfamily Cecidomyiinae, which is the largest subfamily in number of species, 5100, and is divided into four supertribes: Brachineuridi, Stromatosematidi, Cecidomyiidi and Lasiopteridi. The larvae of Cecidomyiinae have mycethophagous, predatory and galling habit, the latter appearing in the supertribes Cecidomyiidi and Lasiopteridi. Gallers are the inducing organisms responsible for malformations of portions of the tissues or organs of plants, known as gall. The relation between the galling insects and their host plants is of high specificity and due to this, for the described species, it is possible to identify them by their type of host-induced gall. Bruggmanniella Tavares, 1909 has 11 species with major distribution in the Neotropical region (eight species) and representatives described for the regions Neartica (one species) and Oriental (two species). In this work, the first cladistic analysis was carried out to understand the kinship relationship between the Bruggmanniela species, the description of a new species from São Paulo State, Brazil. Bruggmanniela species identification key was also updated. In the cladistic analysis, 56 morphological characters were collected for 26 terminal taxa. Of these, 15 belong to the external group and 11 to the internal group. The analysis using heuristic search of equal weights resulted in a single more parsimonious tree with length equal to 148 steps (IC = 0.443 and IR = 0.565) and the search for implicit weighing also generated a single tree with 149 steps (CI = 0.440 and IR = 0.561). The genus Bruggmanniella has its monophyly supported mainly by the absence of thickening of the cephalic margin of the pupa. B. byrsonimae still has uncertain position due to lack of larval stage. The two eastern species originally described in Bruggmanniella, B. actinodaphnes and B. cinnamomi, were placed in the branch of the sister-group Pseudasphondylia, indicating two new combinations: P. actinodaphnes comb. nov and P. cinnamomi comb. nov. We also argue the geographical distribution of Bruggmanniella and Pseudaphondylia species and the occupation of the hosts.