Behavior and feeding of two beetle pollinators of Zamia integrifolia (Cycadales): Rhopalotria slossoni (Coleoptera: Belidae) and Pharaxanotha floridana (Coleoptera: Erotylidae)

Zamia integrifolia L.f. (Cycadales), a threatened cycad native to Florida, depends on 2 native beetle species for pollination: Rhopalotria slossoni (Chevrolat; Coleoptera: Belidae) and Pharaxanotha floridana (Casey; Coleoptera: Erotylidae). Both insects are brood-site pollination mutualists, known to live and feed within the pollen (male) cone. However, for pollination to occur, beetles must also visit ovulate (female) cones, which have been assumed to offer no benefits to them as food or nurseries. We tested the potential for beetle pollinator use of ovulate cones by performing no-choice behavior and feeding trials for adults of both beetle species on both ovulate cones and pollen cones of Z. integrifolia. Rhopalotria slossoni beetles showed greater survival on ovulate cone tissues despite showing no significant difference in total tissue mass consumed between cone sexes. Conversely, P. floridana consumed more tissue mass from ovulate cone scales yet showed no difference in survivorship on ovulate vs. pollen cone scales. Although neither beetle species is found in large numbers on ovulate cones in the field, our laboratory study suggests that both species could potentially benefit from feeding on ovulate cone tissues, questioning the standing hypothesis that Z. integrifolia pollination occurs by deceit.