Flower mites steal <i>Protea neriifolia</i> pollen and nectar

Abstract

Flower mites are well-known nectar and pollen thieves of hummingbird-pollinated plants in the Americas, where they may reduce seed set and alter host population dynamics. They use hummingbirds for transport and are pollinators of some plants. Among African ornithophilous Protea shrubs, the hummingbird-pollination niche is occupied by sugarbirds and sunbirds that often carry substantial numbers of flower mites. The role of these mites in Protea pollination and seed set is unknown. We investigated the role of flower mites as pollinators of ornithophilous Protea neriifolia in South Africa using field-based exclusion experiments. Their role as pollen and nectar consumers was quantified using laboratory-based feeding studies. We demonstrate that even though they consume pollen and nectar, flower mites are not pollinators of P. neriifolia. Quantification of nectar consumption rates indicated that these mites likely have little effect on nectar availability for pollinating birds. However, flower mites may consume more than 50% of available P. neriifolia pollen when mite numbers peak. Flower mites on African ornithophilous Protea may therefore significantly decrease Protea male fitness and significantly impact Protea population dynamics.