Pollination ecology of Stenocereus queretaroensis (Cactaceae), a chiropterophilous columnar cactus, in a tropical dry forest of Mexico

Flowers of columnar cacti are animal-pollinated, often displaying a chiropterophylic syndrome. This study examined if the columnar cactus Stenocercus queretaroensis, a tropical species endemic to western Mexico, is bat-pollinated, by studying its pollination biology and the foraging behavior of potential pollinators. Flowers were produced in winter through spring, peaking in April. Anthesis was nocturnal, and stigma and anther turgidity began around 2200 hours. Production of nectar secretion and highest sugar concentration and energy supply were nocturnal, peaking between 2200 and 2400 hours. Manual auto-pollination and exclusion experiments showed that self-pollination yielded no fruits, while nocturnal pollinators resulted in high fruit set and seed set compared to diurnal pollination treatments. The nectar-feeding bat Leptonycteris curasoae (Phyllostomidae) was the main nocturnal pollinator with the highest effective pollination. Peak bat visitation coincided with peaks in nectar production. The high abundance of L. curasoae throughout the 4-yr study, suggests that it is a seasonally reliable pollinator for this columnar cactus. While pollination syndromes have been increasingly called into question in recent years, this study suggests that at least for this system, there is a fairly close fit between pollinator and pollination syndrome.