Lychee Pollination by the Honeybee

TL;DR: The results indicate that the 'Mauritius' M, bloom does not play an important role as a source of pollen for pollination, and the density of bees found on inflorescences was very low during theM, bloom and increased to very high values during the M 2 bloom.

Abstract: Pollination of lychee (Litchi chinensis Sonn.) by the honeybee was studied in Israel's two commercial cultivars, 'Mauritius' and 'Floridian'. Pollination rate, which was determined in a mixed 'Mauritius' and 'Floridian' plot, followed a consistent pattern: it was low at the first male (M,) 'Mauritius' bloom and reached a high value only when the pseudohermaphroditic (M2) 'Mauritius' bloom started. Pollen density on bees collected from 'Mauritius' inflorescences was very low during the M, bloom and increased to very high values during the M 2 bloom. These results indicate that the 'Mauritius' M, bloom does not play an important role as a source of pollen for pollination. Pronounced, significant, and consistent differences in nectar volume per flower and sugar concentration in the nectar were found between M 1, M2, and female (F) 'Mauritius' flowers. Values were very high in F flowers, medium in M 2 flowers, and low in M, flowers. Accordingly, the density of bees found on inflorescences was high during the F bloom, intermediate during the M 2 bloom, and low during the M1 bloom. The positive correlation between bee density and sugar concentration in the nectar was highly significant for M2 and F 'Mauritius' flowers. The nectar contained three sugars: glucose (43%), fructose (39%), and sucrose (18 %). This ratio was the same in nectar from M 1, M2, and F 'Mauritius' flowers. The lychee, which originated in China, was introduced to Israel in the 1930s. Only two cultivars have been planted commercially: 'Mauritius', introduced from South Africa, and 'Floridian', intro- duced from the U.S. The latter is probably a seedling of cv. Brewster (Degani et al., 1995b). Low productivity of the commer- cial lychee orchards in Israel prompted a study of its pollination. Lychee flowering in Israel occurs in late spring and lasts for about a month. Three distinct flowering waves can usually be observed in every in florescence. Each wave consists of flowers of the same type: the first wave consists of male flowers (M 1), the