Flowering phenology, seed set and arthropod guilds in Trichogoniopsis adenantha (DC) (Asteraceae) in south-east Brazil1

(Flowering phenology, seed set and arthropod guilds in Trichogoniopsis adenantha (DC) (Asteraceae) in south-east Brazil). Trichogoniopsis adenantha (Asteraceae) is a shrub plant that inhabits forest margins and glades. This species blooms throughout the year, attracting arthropods of various guilds, including herbivores, pollinators and predators. In this study, done over a two year period, we described the phenology of T. adenantha and assessed the seasonal variation in arthropod numbers of different guilds. We also determined the periods of lowest and highest seed set. T. adenantha population showed a peak in flowering in March-April (rainy season) with greater production of achenes in December-April. April and October had respectively highest and lowest number of fertilized, undamaged ovules, and this pattern is possibly related with population dynamics of pollinators and herbivores. In August, which was the period of greatest damage to the stigma (by geometrid larvae), there was a positive relationship between the proportion of unfertilized ovules and flowers with damaged stigma, suggesting that floral herbivory may affect reproduction in T. adenantha. We discuss the complex dynamics of the beneficial and harmful interactions between arthropods and the host plant.