Florivory Effects on Pollinator Preference and The Reproductive Output of A Threatened Living Rock Cactus, Ariocarpus retusus (Cactaceae)

Abstract

Florivory reduces pollinator visits and plant fitness due to the elimination of gametes and floral reproductive organs. Longevity and floral synchrony favors escape from florivores and increases resources for pollinators. We study the effects of natural and experimental florivory and if synchrony can diminish it. We determined the floral longevity and phenology of a living rock cactus population in Tamaulipas, Mexico. Open flowers were counted to estimate floral synchrony using the Marquis index. Floral longevity was established (n = 21 flowers). Florivory frequency was recorded indicating the phase of the damaged flower (floral bud, open or closed flower) and the structure (perianth, stigma and anthers) of which some percentage of tissue was removed (25, 50 and 100%) (284 flowers and 150 floral buds; 245 individuals). Flowers with natural damage to reproductive organs and gametes were quantified to determine the direct effect of florivory. Variations in the frequency of pollinators were evaluated with a paired experiment of artificial florivory: whole flower (control) and flower with removal of 50% of the perianth; taxonomic group of pollinators and florivores was recorded and the activity they carried out. Floral longevity varies from one to three days. Flowering is synchronous (S = 0.53 ± 0.09). In the population, 10.2% of the flowers and 2.6% of the floral buds presented florivory, the perianth of the flowers is the most predated. Artificial florivory does not reduce the frequency of pollinators; we argue that visitors do not discriminate between damaged and intact flowers. Florivory does not limit the masculine function because pollen search is the main activity. A total of 2% of the structures were partially (stigma) or totally consumed by Coleoptera (Cryptorhynchinae) and Lepidoptera, reducing the fruit-set due to the death of the flower.