Supplementing bumblebees to ‘Mauritius’ lychee improves yield

Honeybees (HB) are strongly attracted to lychee flowers and serve as the main pollen vector in most lychee orchards throughout the world. Despite precise protocols for managing HB in Israeli lychee orchards, we suspected that the full pollination potential of the orchards was not being achieved and that yields could be increased. Since bumblebees (BB) forage in harsh weather and at lower temperatures than HB, in previous studies we questioned if adding BB to HB in apple and pear orchards would increase fruit set and yield. Encouraged by the important results, we examined this approach in lychee in the present work. The experiments were conducted for three years, resulting in a significant increase in lychee fruit set and yield. Our observations revealed that BB contribute to lychee pollination not only because they are active in conditions that HB are not, but also because HB collect mainly nectar from the lychee flowers and barely contact the reproductive organs, while BB collect mainly pollen and hence pollination increases. As a result of this work, since 2018 10 BB hives per hectare have been introduced into many lychee orchards in Israel in addition to the standard 2.5 HB hives per hectare.