Butterflies provide pollination services to macadamia in northeastern Brazil

Abstract

The increasing global appreciation of macadamia nuts (Macadamia integrifolia, Proteaceae) and plans for expanding their production require appropriate management to support pollination services, since macadamia orchards depend on pollinators to assure high nut yields. Brazil is the 8th largest producer of macadamia nuts globally; however, studies on the pollination services associated with Brazilian orchards are insufficient. In this study, a survey of pollinators associated with the experimentally-introduced macadamia in NE Brazil is presented. The pollination requirements of the orchard studied were experimentally evaluated. Macadamia yields mainly benefited from the pollination service provided by butterflies rather than bees; butterflies were responsible for more than 50% of floral visits. These pollinators aided in ensuring fruiting success of inflorescences in the same magnitude as hand cross-pollination. Cross-pollination also increased final fruit set, but not kernel weight. Therefore, the studied macadamia orchard requires pollination services to optimize the production under local abiotic conditions, and butterflies are its potential pollination agents. For now, the main recommendations to implement in macadamia orchards in the region consists of conserving forest fragments to support pollinating butterflies, and including different cultivars, since outcrossing is required to ensure increased nut yields. Nevertheless, further investigation is needed to test the contributions of other pollinators, mainly stingless bees, to macadamia production supply in scenarios of large-scale crops.