Efficient floret inspection by honeybees in capitula of Carduus acanthoides

Abstract. 1. The floret inspection by honeybees Apis mellifera ligustica on inflorescences of Carduus acanthoides was studied in a natural patch. First-day stage capitula were protected with a net hood against insect visits. The next day, the net hood was removed at the time of maximal nectar accumulation, allowing a bee to visit the inflorescence. Walking trajectories on the capitula, the number of florets inspected and the duration of the visit were recorded. After the bee's departure, the inflorescence was cut off and analysed in the laboratory to determine the presence or absence of nectar in each of its florets.
2. Bees made inspection trajectories without a defined systematic pattern.
3. The number of floret inspections performed represented a high percentage of the available florets (57.37 ± 2.81%; mean ± SE; n = 8).
4. The number of depleted florets coincided with the number of floret inspections.
5. The number of times a floret is visited in a bee's trajectory is non-random.
6. Strategies that might account for this high foraging efficiency are discussed.