Hygienic behaviour in the Australian stingless bees Tetragonula carbonaria and T. hockingsi

Hygienic behaviour is a natural mechanism of colony-level disease resistance to brood pathogens and has been reported in honey bees and stingless bees. A novel brood disease was recently confirmed in the Australian stingless bees Tetragonula carbonaria Smith and Tetragonula hockingsi Cockerell and there is a paucity of data available on hygienic behaviour in these species. To address this, we investigated hygienic behaviour in eight colonies of T. carbonaria and four colonies of T. hockingsi, using brood freeze-kill and pin-kill assays. Hygienic behaviour was present in both species and was rapidly expressed in both assays. In T. carbonaria, the mean time (± SE) for removal of freeze-killed and pin-killed brood was 9.1 ± 1.9 hours and 8.2 ± 0.9 hours, respectively (n=8; one trial per assay). In T. hockingsi, removal of freeze-killed and pin-killed brood was 14.1 ± 5.1 hours and 10.4 (no SE) hours, respectively. There was no significant difference (α=0.05) in time taken to complete the hygienic behaviour phases (detection, uncapping, removal or cell dismantling) between assay type or assay order in both species. However, intercolony variation was observed in both species in the assays, suggesting that like honey bees, hygienic behaviour may have a genetic component. Tetragonula carbonaria and T. hockingsi displayed significantly faster detection, uncapping, removal and cell dismantling times than any of the stingless bees or most honey bees studied previously. This may, in part, explain why stingless bees appear to suffer from relatively few brood diseases

Ice stream subglacial access for ice-sheet history and fast ice flow: the BEAMISH Project on Rutford Ice Stream, West Antarctica and initial results on basal conditions

Three holes were drilled to the bed of Rutford Ice Stream, through ice up to 2154 m thick, to investigate the basal processes and conditions associated with fast ice flow and the glacial history of the West Antarctic Ice Sheet. A narrative of the drilling, measuring and sampling activities, as well as some preliminary results and initial interpretations of subglacial conditions, is given. These were the deepest subglacial access holes ever drilled using the hot-water drilling method. Samples of bed and englacial sediments were recovered, and a number of instruments were installed in the ice column and the bed. The ice–bed interface was found to be unfrozen, with an existing, well-developed subglacial hydrological system at high pressure, within ~1% of the ice overburden. The bed itself comprises soft, water-saturated sediments, consistent with previous geophysical interpretations. Englacial sediment quantity varies significantly between two locations ~2 km apart, and possibly over even shorter (~20 m) distances. Difficulties and unusual observations encountered while connecting to the subglacial hydrological system in one hole possibly resulted from the presence of a large clast embedded in the bottom of the ice

Harmonic radar tracking reveals that honeybee drones navigate between multiple aerial leks

Male honeybees (drones) are thought to congregate in large numbers in particular “drone congregation areas” to mate. We used harmonic radar to record the flight paths of individual drones and found that drones favored certain locations within the landscape which were stable over two years. Drones often visit multiple potential lekking sites within a single flight and take shared flight paths between them. Flights between such sites are relatively straight and begin as early as the drone's second flight, indicating familiarity with the sites acquired during initial learning flights. Arriving at congregation areas, drones display convoluted, looping flight patterns. We found a correlation between a drone's distance from the center of each area and its acceleration toward the center, a signature of collective behavior leading to congregation in these areas. Our study reveals the behavior of individual drones as they navigate between and within multiple aerial leks

On the algebraic structure of conditional events: 13th European conference, ECSQARU 2015, Compiègne, France, July 15-17, 2015.

This paper initiates an investigation of conditional measures as simple measures on conditional events. As a first step towards this end we investigate the construction of conditional algebras which allow us to distinguish between the logical properties of conditional events and those of the conditional measures which we can be attached to them. This distinction, we argue, helps us clarifying both concepts

Bumble bees strategically use ground level linear features in navigation

Extended ground level structures like roads or field edges can be important cues for navigating animals,seen for example in road-following pigeons. In a landscape devoid of skyline cues but with a rectangular grid of pathways and roads, we used harmonic radar to track free-flying bumble bees,Bombus terrestris. Individual bees consistently used ground level linear features for navigation in a wide range of behavioural contexts. Bee exploration flights, search behaviour and foraging routes were shaped by linear features, with bees frequently flying along and parallel to pathways and roads. Comparisons off light trajectories across these behavioural contexts show that individuals modulated their use of linear features strategically with respect to their individual goals and experience. Bees searching for a feeder used linear features to target their search, while foragers often followed pathways to return to their hive without overshooting. These findings on a major pollinator have important implications for the placements of bee colonies for agriculture and floral resources for conservation