Novel ways to assess the density and distribution of sugarbag bees

A project undertaken at the School of Life and Environmental Sciences, The University of Sydney, and supervised by Dr Ros Gloag and Prof Ben Oldroyd

Many seed, vegetable and fruit crops depend on pollination by bees. The security of these food crops rests predominantly with managed and feral populations of a single bee species: the honey bee. Global instability in honey bee populations, however, have lead to calls to better enlist some of the world’s other bee species as alternative crop pollinators. Stingless bees (Meliponini) are top candidates for this role: like honey bees, they live in colonies comprising a queen and many workers, pollinate diverse plants and produce honey. They have a large native distribution spanning the global tropics and subtropics, including Australia, and are proposed pollinators of key fruit crops grown in these regions. Their pollination services can be exploited simply by encouraging their presence in relevant orchards. Furthermore, knowledge of how to maintain these bees in agricultural landscapes will have knock-on benefits for their conservation in the wild, where they provide key ecosystems services. 

A critical first step is to develop a tool for estimating the density and distribution of stingless bee populations. Most social bees nest in trees and other cavities, which makes them cryptic and challenging to survey by traditional means. This problem has been overcome in honey bees via a protocol that exploits the bees’ reproductive biology. Male bees (drones) gather in large numbers at mating aggregations awaiting queens. If the typical distance that drones travel from their natal nests to an aggregation is known, then these drones can be sampled, genotyped, assigned to colonies, and thus used to estimate the number of colonies in the catchment area.

This project aims to:

  1. Develop a protocol for estimating colony density of the Australian stingless bee Tetragonula carbonaria, based on collections of males from mating aggregations;
  2. Implement the protocol to make the first-ever estimates of population densities of a stingless bee in Australian rural and natural landscapes. These estimates will form the basis of future efforts to increase stingless bee abundance in target areas for crop pollination; and
  3. Advance understanding of the reproductive biology and ecology of T. carbonaria.

Sample collections are now underway, in collaboration with Kuringai Council, Sydney and Dr Tim Heard of Sugarbag Bees.

Figure 1. The entrance of a natural nest of the stingless bee, T. carbonaria (photo: R. Stephens).

Figure 2. The nest structure of T. carbonaria (photo: R. Gloag).