Pollination of radish byApis cerana

Abstract

SUMMARYIn the Kathmandu valley of Nepal radish (Raphanus sativus) plants had an average often branches, each with 155.2 ± 18.3 flowers, 14.1 ± 1.3 mm in diameter. Flowers opened in the morning and remained open for two to three days. Flowering began in the first week of March and lasted for one month. Apis cerana workers foraged on radish plants for 11.5 hours each day, from 06.40 h (26 min after sunrise) to 18.30 h (18 min after sunset) with peak foraging between 11.00 h and 14.00 h. At 09.00, 12.00 and 15.00 h respectively, workers averaged 4.3, 5.3 and 12.8 s per flower, visited 8.0, 9.0 and 5.0 flowers per minute and collected 11, 10 and 7 mg of pollen. Most workers collected either pollen or nectar, but 4–7% collected both nectar and pollen during the same foraging trip. Pod set, number of seeds per pod, seed weight and germination for radish plants caged with an A. cerana colony were 45%, 42%, 45% and 73% greater, respectively, than for open-pollinated plants. Plants with insect visitors excluded had no pod set.