Florivory by the occupants of phytotelmata in flower parts can decrease host plant fecundity

Abstract

Some types of plant accumulate liquid in their inflorescences creating phytotelmata. These environments protect the flowers against florivory, although they may be colonized by aquatic or semi-aquatic florivorous insect larvae, whose effects on the fitness of the plants remain unclear. We tested the hypothesis of floral antagonism by the occupants of phytotelmata, which predicts that florivory by the occupants of the phytotelmata represents a cost to the female fitness of the plant, reducing its fecundity. We manipulated experimentally the infestation by three florivores larvae species occupants of phytotelmata in inflorescences of Heliconia spathocircinata (Heliconiaceae) to test for negative direct trophic effects on the fecundity of the flowering and fruiting bracts. We found that the foraging of the hoverfly (Syrphidae) and moth (Lepidoptera) larvae in the inflorescences contributed to a decline in the fecundity of the plant. While the lepidopteran impacted fecundity when foraging in both flowering and fruiting bracts, the syrphid only affected the fruiting bracts, which indicates that the nectar and floral tissue are the principal resource exploited by the hoverfly. By contrast, soldier fly (Stratiomyidae) had a neutral effect on fecundity, while foraging in flowering or fruiting bracts. These findings corroborate our hypothesis, that herbivory by the larval occupants represents cost to the host plant having phytotelmata. The negative influence of this foraging on plant fecundity will nevertheless depend on the consequences of the exploitation of resources, which vary considerably in ephemeral habitats such as the phytotalmanta of flower parts.

Effects of the availability of floral resources and neighboring plants on nectar robbery in a specialized pollination system

“…Considering that H. spathocircinata is a widespread hummingbird-pollinated species in Brazil, the study of the spatial and temporal variation in the nectar-robbing patterns of this plant may provide valuable insights into the relationships between ornithophilous host plants and floral visitors. As plant–animal interactions in Heliconia pollination systems are complex and tend to be specialized ( Cruz et al 2007 ; Temeles et al 2013; Missagia and Alves 2021 ), future studies should investigate whether nectar robbing influences the reproduction of the plant at both the population and community levels ( Irwin et al 2001 ), by balancing selective pressures or reinforcing specialized traits ( Santos et al 2020 ; Rojas-Nossas et al 2021 ). The findings of this study are fundamentally important, given that they emphasize the complexity of developing a strategy to both attract pollinators and avoid floral robbers.…”