Without Moths or Bats, Cacti form Friendships with Bees: Reproductive Biology of the Queen of Night Selenicereus Setaceus (Cactaceae) in São Thomé Das Letras, Brazil

Epiphyte, hemiepiphyte and scandent cacti comprise about 10% of the total species of Cactaceae and are the least studied group in the family. Despite the close relationship of Selenicereus setaceus with the well-known and internationally traded pitahayas / dragon-fruit crops, researchers have only recently increased their study of this species. Selenicereus setaceus is the only species of the genus that occurs in the southern American continent; the genus has its center of diversity in Central America and Mexico. Experiments using exclusion methods were carried out to monitor reproductive success and determine which floral visitors were effective pollinators of S. setaceus in southeastern Brazil. Pollination treatments were carried out to determine the reproductive system of the species in addition to observations to unveil the phenology and quantify the volume and concentration of sugars of the nectar produced during anthesis. The Apis mellifera bee was the most frequent visitor and the main pollinator of the S. setaceus flowers. The studied population is self-compatible and fruits with manual or spontaneous self-pollination through physical contact between the anthers and the stigma lobes during flower closing. The nectar had an average sugar concentration of 28.3% and an average volume of 133µl. Although the floral characteristics fit into the sphingophily and chiropterophily syndromes, natural pollination occurred mainly from daytime visitation by A. mellifera, which promotes both self-pollination and cross-pollination mainly during the flower closing period between 5:00 am and 10:00 am. In addition, spontaneous self-pollination also contributed to increasing the rate of fruiting, since visits by nocturnal pollinators were rare.

Nocturnal pollinators strongly contribute to pollen transport of wild flowers in an agricultural landscape

Dramatic declines in diurnal pollinators have created great scientific interest in plant–pollinator relationships and associated pollination services. Existing literature, however, is generally focused on diurnal pollinating insect taxa, especially on Apidae (Hymenoptera) and Syrphidae (Diptera) pollinators, while nocturnal macro-moths that comprise extremely species-rich flower-visiting families have been largely neglected. Here, we report that in agricultural landscapes, macro-moths can provide unique, highly complex pollen transport links, making them vital components of overall wild plant–pollinator networks in agro-ecosystems. Pollen transport occurred more frequently on the moths' ventral thorax rather than on their mouthparts that have been traditionally targeted for pollen swabbing. Pollen transport loads suggest that nocturnal moths contribute key pollination services for several wild plant families in agricultural landscapes, in addition to providing functional resilience to diurnal networks. Severe declines in richness and abundance of settling moth populations highlight the urgent need to include them in future management and conservation strategies within agricultural landscapes.