Pollination of cycads in an urban environment

Abstract

Research on urban systems has documented the contributions of cities as sites where insect pollinators undergo their life cycles, contributing to the reproduction of many groups of plants. However, reports of plants whose reproduction is assisted by specialist pollinators under conditions prevalent in cities are scarce. Cycads and insect pollinators are threatened mainly by loss and modification of their habitats. Here, we describe two cases in which cycad species from two genera distributed in Mexico (Ceratozamia tenuis (Dyer) D.W. Stev. & Vovides and Dioon edule Lindl.) reproduce and germinate successfully in urban areas, aided by insects, near their natural distribution areas. The plants examined were artificially planted in different gardens within the city of Xalapa-Enríquez. We found that specimens two genera of insect pollinators, Pharaxonotha sp. (Erotylidae: Pharaxonothinae) on C. tenuis, and Parallocorynus sp., (Belidae: Oxycoryninae) on D. edule, can survive in cycad pollen strobili, maintaining ecological interactions as they would occur in wild, conserved environments. In addition, we found beetles in ovulate strobili during the pollen receptivity phase, which suggests that they effectively reach ovulate strobili with pollen from pollen strobili. Characterization of this gymnosperm–beetle pollination system, which is unexpected in urban areas due the effects of human disturbance on insect communities, could promote new conservation biology research on flagship species in environments and landscapes shaped by anthropogenic impacts.