Pollination system of Corylopsis gotoana (Hamamelidaceae) and its stonefly (Plecoptera) co-pollinator

The order Plecoptera is primarily known for its aquatic nymphs and their importance in many stream ecosystems. However, the biology and life history of Plecopteran terrestrial adults is mostly unknown, and hence interactions with plants have rarely been documented. Here, we report on insect visitation to flowers of Corylopsis gotoana (Hamamelidaceae) in a temperate forest of Japan, with emphasis on the behavior and pollination role of adults of a stonefly species, Strophopteryx nohirae (Taeniopterygidae), which were frequently observed in the flowers. The most frequent insect visitors to Corylopsis flowers were Bombylius major (Bombyliidae), Apis cerana (Apidae) and Bombus ardens (Apidae), all of which were considered main pollinators because of high rates of visitation and pollen attachment. Strophopteryx nohirae frequently visited Corylopsis trees, on which they foraged for pollen and mated. A field experiment on the pollination success of Corylopsis flowers visited by S. nohirae verified that this stonefly contributed to pollination.