Impacto dos herbívoros endofíticos nas flores de espécies simpátricas de Malpighiaceae no Cerrado

Abstract

Plant–animal interactions play a key role in maintaining biodiversity and are influenced by environmental conditions. Plants provide shelter and food resources to animals, which in turn may offer ecosystem services such as pollination, particularly by insects. However, among floral visitors, many species do not contribute to pollination and instead consume reproductive tissues. A common example includes endophytic herbivores, which remain concealed within developing floral buds, with guaranteed food for their development while receiving shelter and protection against most of their natural enemies. The main objective of this study was to determine the abundance and identity of endophytic herbivores in floral buds, and to investigate whether these herbivores migrate between species within the same plant family throughout the year. We examined 90 individuals from six native and common species of the Malpighiaceae family in the Brazilian Savannah: Banisteriopsis campestris, B. laevifolia, B. malifolia, Byrsonima intermedia, Heteropterys pteropetala, and Peixotoa tomentosa. Each species had 300 floral buds at the pre-anthesis phase collected from 15 plants. In the laboratory they were examined under a stereomicroscope for internal herbivores and associated parasitoids. The three Banisteriopsis species had the highest abundance of endophytic herbivores, particularly B. campestris and B. malifolia. The main adult herbivores were beetles from four species of the genus Anthonomus (Curculionidae), which infested the three Banisteriopsis species and H. pteropetala, sequentially occupying their floral buds throughout the year. Lepidopteran larvae were also found, although in lower abundance and only in B. campestris and P. tomentosa. Female endophytic herbivores oviposited in flower buds, where the larvae mainly damaged fertile structures, especially the anthers. As the larvae damage in the reproductive tissues occured prior to inflorescence maturation, the resources invested by the plant were wasted and resulted in floral bud abortion. Four species of parasitoid Hymenopterans associated with the herbivores were identified, and always in low density, except in H. pteropetala where no parasitoids were observed. Consequently, although present the parasitoids were largely ineffective in controlling endophytic herbivore populations. We conclude that the damage caused by endophytic herbivory represents a natural factor that negatively impacts the reproduction of Malpighiaceae species, as reproductive fitness is directly affected by gamete loss and the decreased visual attractiveness of the inflorescences.