- A P du Toit and D J Swart
- Apicultural Unit, Plant Protection Research Institute, Private Bag X134, Pretoria 0001
- 1995
Honeybee foraging activity in a litchi orchard was monitored by investigating returning foragers for nectar, water, pollen and bee-glue. At commencement of flowering, 24 beehives were introduced into a 10 ha orchard. Honeybee foragers remained active on litchi blossoms throughout the day as well as during the entire flowering period. Nectar foraging was highest in the morning, while pollen foraging reached a peak at noon. Honeybees also collected pollen from black-jack, dandelion, blue weed, silky oak, pecan nut, avocado and blue-gum in or around the litchi orchard. Water was collected mainly in the afternoon. Fruit-set was studied in a second experiment where 200 panicles were marked on 10 trees and left open. A second set of 300 panicles on 15 trees was bagged with 1 mm2 gauze to exclude insects. A mean set of six fruits (range 0 -26) per open-pollinated panicle was recorded, compared to less than two fruits per bagged panicle. The mean weight per fruit was 14 g for open panicles.
Summary:
The study monitored honeybee foraging activity in a Bengal litchi orchard during the 1993 flowering season at Politsi in South Africa.
At the start of flowering, 24 beehives were placed in a 10-hectare orchard to improve pollination.
Honeybees actively foraged on litchi blossoms all day and throughout the flowering period.
Nectar foraging was highest in the morning; pollen foraging peaked at noon.
Bees also collected pollen from other plants near the orchard, including black-jack, dandelion, blue weed, silky oak, pecan, avocado, and blue-gum.
Water collection by bees occurred mainly in the afternoon.
Fruit-set experiments compared open-pollinated panicles (exposed to bees) versus bagged panicles (insect-excluded).
Open-pollinated panicles had a mean of 6 fruits per panicle (range 0–26), while bagged panicles averaged fewer than 2 fruits per panicle.
Fruit size was similar between treatments (mean weight ~14–16 g per fruit).
Insect pollination enhanced fruit set dramatically, with a 300% increase in fruit set for open-pollinated inflorescences.
The study illustrates that, despite litchi being self-fertile, limited self-pollination occurs, and active pollinators like honeybees are essential for optimal fruit set.
High levels of unsuccessful foragers (bees returning without loads) were noted early in the day and decreased by late afternoon.
The timing and amount of nectar and pollen collection varied through the flowering period due to new flushes of inflorescences.
Overall, honeybee activity is crucial for successful litchi fruit production in South Africa due to their effectiveness as pollinators.