Stingless bees as effective managed pollinators for Australian horticulture (PH16000)

What was it all about?

From 2017 to 2023, this project explored the potential of stingless bees as managed crop pollinators by testing their effectiveness with selected field crops and suitability as glasshouse crop pollinators. Honeybees are currently seen as the industry-standard pollinator, but availability, disease, and the varroa mite incursion suggest that other avenues should be explored.

The leading candidates are stingless bees, which live in large colonies (like honeybees), pollinate various plants and can be kept in managed hives. There is a growing number of stingless beekeepers, and stingless bees are already used in macadamia farms, where they outperform honeybees. Stingless bees (particularly Tetragonula species) are used in crop pollination in several Asian countries, such as India and Thailand, but Australia has underdeveloped potential.

The project reviewed the evidence on the potential of stingless bees and other native bees as managed pollinators adding value to Australian horticulture. Experimental studies were carried out on a range of fruit and vegetable crops (both tropical and temperate), testing first if the bees had visited the flowers and transported the crop pollen. Where they had, the effectiveness of stingless bee pollination was then tested, and its impact on crop set/yield/quality as appropriate. For the most promising crop/bee combinations, more detailed studies were conducted to determine the best ways to deploy managed hives within the target crop. In addition, similar tailored studies of the potential of stingless bees to be effectively managed by pollinators in glasshouse conditions were undertaken. The glasshouse is an unnatural environment for bees, so specific studies were conducted to determine how to manage glasshouses for healthy stingless bee populations.

The research shows that stingless bees have exciting potential as managed pollinators in mango, lychee and, with some caveats, avocado. In addition, it was found that wild stingless bees are the main pollinators of mangoes in Northern Territory orchards. Stingless bees are also excellent pollinators of macadamia, and the timing of hive deployment relative to crop flowering influences their fidelity to the crop, and that recently split hives have performed poorly because foragers are highly focused on collecting resin after a colony split.

The research team also conducted experiments with several cucurbits but found that neither of the two commonly kept Tetragonula bees were inclined to visit flowers, precluding further study. In contrast, the same bees were excellent pollinators of strawberries in the National Vegetable Protected Cropping Centre glasshouse. The research found that colonies deployed in glasshouses initially lost weight rapidly and showed reduced activity before stabilising and providing good crop pollination. When returned to the external environment after the crop rotation, they rapidly regained weight and increased activity levels. These results suggest that stingless bees can also be excellent glasshouse pollinators but should only be used for relatively short periods, interspersed by periods in good foraging situations outdoors.