Stingless Bee Tetragonula Research Articles

The upside of recognition error? Artificially aggregated colonies of the stingless bee Tetragonula carbonaria tolerate high rates of worker drift

The upside of recognition error? Artificially aggregated colonies of the stingless bee Tetragonula carbonaria tolerate high rates of worker drift

Flower detection and acuity of the Australian native stingless bee Tetragonula carbonaria Sm.

We tested the endemic Australian Tetragonula carbonaria bee as a model of how colour vision may allow these small bees to find flowers. In a Y-Maze apparatus, we presented stimuli that contained both chromatic- and green-receptor contrasts, or only had chromatic contrast to free flying bees. Stimuli were detected at visual angles of 9.5° and 9.3°, respectively. We next made morphological measurements of the compound eye under high magnification using a digital microscope, and despite a relatively small eye size with a surface area of 0.64±0.02mm(2), the compound eye contained 3010±10 ommatidia. Measurements of diverging rays of light using antidromic illumination revealed a mean interommatidial angle in the frontal visual field measures 1.56°±0.10°. Finally, we calculate that the minimum number of ommatidia that need to be excited for object detection is 33, which is much higher than for object detection in bumblebees and for the detection of objects providing both colour and green contrasts by honeybees, but lower for the detection of an object lacking green contrast in honeybees. We discuss reasons that may explain potential tradeoff for foraging bees.

Innate colour preferences of the Australian native stingless bee Tetragonula carbonaria Sm.

Innate preferences promote the capacity of pollinators to find flowers. Honeybees and bumblebees have strong preferences for 'blue' stimuli, and flowers of this colour typically present higher nectar rewards. Interestingly, flowers from multiple different locations around the world independently have the same distribution in bee colour space. Currently, however, there is a paucity of data on the innate colour preferences of stingless bees that are often implicated as being key pollinators in many parts of the world. In Australia, the endemic stingless bee Tetragonula carbonaria is widely distributed and known to be an efficient pollinator of both native plants and agricultural crops. In controlled laboratory conditions, we tested the innate colour responses of naïve bees using standard broadband reflectance stimuli representative of common flower colours. Colorimetric analyses considering hymenopteran vision and a hexagon colour space revealed a difference between test colonies, and a significant effect of green contrast and an interaction effect of green contrast with spectral purity on bee choices. We also observed colour preferences for stimuli from the blue and blue-green categorical regions of colour space. Our results are discussed in relation to the similar distribution of flower colours observed from bee pollination around the world.

Resources or landmarks: which factors drive homing success in Tetragonula carbonaria foraging in natural and disturbed landscapes?

To date, no study has investigated how landscape structural (visual) alterations affect navigation and thus homing success in stingless bees. We addressed this question in the Australian stingless bee Tetragonula carbonaria by performing marking, release and re-capture experiments in landscapes differing in habitat homogeneity (i.e., the proportion of elongated ground features typically considered prominent visual landmarks). We investigated how landscape affected the proportion of bees and nectar foragers returning to their hives as well as the earliest time bees and foragers returned. Undisturbed landscapes with few landmarks (that are conspicuous to the human eye) and large proportions of vegetation cover (natural forests) were classified visually/structurally homogeneous, and disturbed landscapes with many landmarks and fragmented or no extensive vegetation cover (gardens and plantations) visually/structurally heterogeneous. We found that proportions of successfully returning nectar foragers and earliest times first bees and foragers returned did not differ between landscapes. However, most bees returned in the visually/structurally most (forest) and least (garden) homogeneous landscape, suggesting that they use other than elongated ground features for navigation and that return speed is primarily driven by resource availability in a landscape.

Urban gardens promote bee foraging over natural habitats and plantations.

Increasing human land use for agriculture and housing leads to the loss of natural habitat and to widespread declines in wild bees. Bee foraging dynamics and fitness depend on the availability of resources in the surrounding landscape, but how precisely landscape related resource differences affect bee foraging patterns remains unclear. To investigate how landscape and its interaction with season and weather drive foraging and resource intake in social bees, we experimentally compared foraging activity, the allocation of foragers to different resources (pollen, nectar, and resin) and overall resource intake in the Australian stingless bee Tetragonula carbonaria (Apidae, Meliponini). Bee colonies were monitored in different seasons over twoyears. We compared foraging patterns and resource intake between the bees' natural habitat (forests) and two landscapes differently altered by humans (suburban gardens and agricultural macadamia plantations). We found foraging activity as well as pollen and nectar forager numbers to be highest in suburban gardens, intermediate in forests and low in plantations. Foraging patterns further differed between seasons, but seasonal variations strongly differed between landscapes. Sugar and pollen intake was low in plantations, but contrary with our predictions, it was even higher in gardens than in forests. In contrast, resin intake was similar across landscapes. Consequently, differences in resource availability between natural and altered landscapes strongly affect foraging patterns and thus resource intake in social bees. While agricultural monocultures largely reduce foraging success, suburban gardens can increase resource intake well above rates found in natural habitats of bees, indicating that human activities can both decrease and increase the availability of resources in a landscape and thus reduce or enhance bee fitness.

Assessment of pollen assemblages from the hives of <i>Tetragonula carbonaria</i> for the presence of the threatened species <i>Grevillea parviflora</i> subsp. <i>parviflora</i>

Pollen assemblages from managed hives of the Australian social stingless bee Tetragonula carbonaria were examined for the presence of the threatened species Grevillea parviflora subsp. Parviflora. Managed hives of Tetragonula carbonaria were placed in bushland at Lake Macquarie, New South Wales, Australia, in four known populations of Grevillea parviflora subsp. parviflora through the main flowering period of 12 September to 2 November 2014. Samples of honey and propolis were collected from the hives at the end of this period and analysed using palynology techniques for the presence of Grevillea parviflora subsp. parviflora pollen. Grevillea parviflora subsp. parviflora pollen was detected in all propolis samples from the four study sites but was not found in the honey samples. Field observations identified that honeybees were the dominant insect visitor to Grevillea parviflora subsp. parviflora at all sites. There were no sightings of Tetragonula carbonaria foraging on Grevillea parviflora subsp. parviflora inflorescences during field observations. This study also demonstrates the application of managed hives of the Australian stingless bees Tetragonula carbonaria for monitoring floral diversity where propolis samples can be used to indicate plant species richness (biodiversity) and the presence of specific species relevant to conservation within their foraging area.

Bees at War: Interspecific Battles and Nest Usurpation in Stingless Bees

We provide the first evidence for interspecific warfare in bees, a spectacular natural phenomenon that involves a series of aerial battles and leads to thousands of fatalities from both attacking and defending colonies. Molecular analysis of fights at a hive of the Australian stingless bee Tetragonula carbonaria revealed that the attack was launched by a related species, Tetragonula hockingsi, which has only recently extended its habitat into southeastern Queensland. Following a succession of attacks by the same T. hockingsi colony over a 4-month period, the defending T. carbonaria colony was defeated and the hive usurped, with the invading colony installing a new queen. We complemented our direct observations with a 5-year study of more than 260 Tetragonula hives and found interspecific hive changes, which were likely to be usurpation events, occurring in 46 hives over this period. We discuss how fighting swarms and hive usurpation fit with theoretical predictions on the evolution of fatal fighting and highlight the many unexplained features of these battles that warrant further study.

Emergency queens inTetragonula carbonaria(Smith, 1854) (Hymenoptera: Apidae: Meliponini)

There is increasing interest in the management of stingless bees for crop pollination, honey production and recreational beekeeping. Colony propagation is based on the division of one colony into two smaller colonies. The process generates a queenless colony and requires that the new colony is successful in the production of a new queen. Three different mechanisms by which female larvae develop as queens have been described for stingless bees: (1) genetic determinism with no differentiation in the cells used for rearing queens and workers; (2) queen development is determined by large queen cells; and (3) queen cells are formed by the fusion of two worker-sized brood cells. Colonies of species that utilise specially constructed queen cells cannot be divided artificially unless there are queen cells present at the time of splitting. Here, we show that queenless colonies of the Australian stingless bee Tetragonula carbonaria (Smith, 1854) can construct queen cells by the fusion of two worker-sized cells. This phenomenon is unknown from any other stingless bee species with a spiral brood comb. It has the practical benefit that beekeepers can divide hives even when there are no queen cells present. Finally, it is shown that T. carbonaria workers remain completely sterile in queenless colonies.

Genetic Differentiation of the Stingless Bee Tetragonula pagdeni in Thailand Using SSCP Analysis of a Large Subunit of Mitochondrial Ribosomal DNA

Genetic diversity and population differentiation of the stingless bee Tetragonula pagdeni (Schwarz) was assessed using single-strand conformational polymorphism (SSCP) analysis of a large subunit of the ribosomal RNA gene (16S rRNA). High levels of genetic variation among individuals within each population (North, Northeast, Central, Prachuap Khiri Khan, Chumphon, and Peninsular Thailand) of T. pagdeni were observed. Analysis of molecular variance indicated significant genetic differentiation among the six geographic populations (Φ (PT)=0.28, P<0.001) and between samples collected from north and south of the Isthmus of Kra (Φ (PT)=0.18, P<0.001). In addition, Φ (PT) values between all pairwise comparisons were statistically significant (P<0.01), indicating strong degrees of intraspecific population differentiation. Therefore, PCR-SSCP is a simple and cost-effective technique applicable for routine population genetic analyses in T. pagdeni and other stingless bees. The results also provide an important baseline for the conservation and management of this ecologically important species.