Australian stingless bees improve greenhouse Capsicum production
Mark K Greco, Robert N Spooner-Hart, Andrew G A C Beattie, Idris Barchia and Paul Holford
Australian stingless bees contribute to the pollination of some commercially important field crops, but it is unclear whether they can increase crop production reliably in the greenhouse environment. Three 20 week trials were therefore conducted, each using a different hive of Austroplebeia australis Friese and Trigona carbonaria Smith placed in separate glasshouses containing Capsicum annuum L. A third glasshouse contained C. annuum but no bees. In the third week of each trial, the numbers of pollen grains present on stigmatic surfaces and pollen tubes growing along styles were determined. Changes in brood volume were assessed by x-ray computerised tomography at weeks 1, 10 and 20. Additionally, the hives were weighed at these times. At the end of each trial, fruit diameter and length and their fresh and dry weights were measured as were seed fresh and dry weights. Bee behaviour was recorded in the third trial. T. carbonaria foraged less sporadically on C. annuum flowers than did A. australis, and pollination by both bee species showed their potential to increase fruit yield and quality. The effects of pollination by either species were, however, not consistent among the three trials. Hive weights and brood volumes for all colonies increased, so it is considered that both species thrived whilst being able to pollinate the plants. Both species therefore have the potential to improve fruit yield and quality within the greenhouse environment. It was noted that A. australis caused damage to the styles in each trial. This may be attributed to the foraging strategies employed by this species and further work is needed to determine optimum bee to flower stocking rates.