Tetragonula carbonaria foraging at Gympie

One of my research projects over the summer break (although the extended observations were only completed on the 11/04/12) was to observe the foraging patterns of the Australian native bee species Tetragonula carbonaria during the day. This experiment was conducted over the course of 12 days at two different sites: one with Corymbia torelliana trees nearby (the bees collect resin from these plants and disperse their seeds) and one without these plants at Woondum National Park. The aim was to collect data comparing foraging patterns at both sites before and after theC. torelliana resin capsules (which contain the seeds) were ready. This was achieved by two observers (myself and another student) spending three days at the C. torelliana site and three days at the National Park site before and after the capsules had opened. Unfortunately, not all the days were consecutive (because of weather and other commitments) and when we had time to do the final six days of observations, the capsules were already gone due to bad weather and an early season.

The specific activity which was recorded included the number of foragers entering and leaving hives, the number who came back with pollen, resin and seeds, and finally the number which left with seeds or with waste bundles (unlike honey bees, social native bees will defecate in their hive and remove it along with other waste). Of the six hives observed at each site, 15 minutes was spent recording data for each three times a day between 10-12pm, 12-2pm and 2-4pm.

Tetragonula carbonaria hive at Gympie

Results

This study found that while foraging numbers remained relatively constant over the course of the day, as you can see from the graphs of both sites below, pollen foraging significantly decreased as the day wore on.

Mean percentage of pollen foragers at the Corymbia torelliana site

Mean percentage of pollen foragers at the National Park site

This could well mean that the bees either exhaust their supply of pollen early on in the day, or they cease to require as much of it after the initial rush in the morning. The full study comparing the foraging activity between the different sites will be written up by Professor Helen Wallace who supervised me for this project