Temporal variation in extrafloral nectar secretion by reproductive tissues of the senita cactus, Pachycereus schottii (Cactaceae), in the Sonoran Desert of Mexico

摘要

Plant/ant interactions mediated by extrafloral nectar (EFN) are common in nature. EFN is produced by plant species of >330 genera across 25% of all angiosperm families. Despite natural history observations suggesting its widespread occurrence within the Cactaceae, few studies have quantified EFN production by cacti. In this study, we conducted ant-exclusion experiments to examine temporal variation in, and ant consumption of, EFN produced by buds and fruits of the senita cactus (Pachycereus schottii) in the Sonoran Desert. EFN production by both buds and fruits was greatest at night and nearly absent by day. EFN remaining on buds and fruits was lower (and nearly absent) with ants than without ants. These results suggest the need for further studies of senita and other cacti that examine the ability of EFN production to attract and reward, but not necessarily oversupply ant consumers that provide them with herbivore resistance.