Comparative anatomy of male genital organs in the genus Apis.

Comparative morphological studies of male genitalia from 6 honey bee species revealed distinct qualitative differences in each species in both everted endophalli and endophalli in situ. The endophalli in situ can be studied in drones preserved in ethanol. The following characters are most suitable for classification in situ: 1) pattern of the ventral hairy field of the vestibulum; 2) number of folds and hairy patches of the ventral cervix; 3) form of the dorsal hairy field of the cervix; and 4) the form of its appendage (lobe). Three types of endophalli can be classified. One type is present in the cavity-nesting honeybees A mellifera, A cerana and A koschevnikovi, the second in the free-nesting dwarf honeybees A andreniformis and A florea and the third in the A dorsata complex

Reproductive isolation by different time of drone flight between Apis cerana (Fabricius, 1793) and Apis vechti (Maa, 1953)

In Sri Lanka the three honeybee species Apis florea, Apis cerana and Apis dorsata are found in the same biotope. The daily periods of drone flight were found to be specific O( ENIKGER and AW-YALGUN1ASE K,ERA 1976). According to NT RUETR (1988) this behavioral isolation is a more complete separation than the reproductive barrier between A. mellifera and A. cerana. The three honeybees, A. cerana, A. vechti and A. dorsata are naturally distributed in the same habitat. We compared the time of drone flight between these honeybees in Sabah (North East Borneo)

Drones of Apis dorsata (Fabricius 1793) congregate under the canopy of tall emergent trees in Borneo.

The drones of Apis dorsata performed their mating flights at dusk. They took off simultaneously from the colonies. The flying drones produced a distinct hum which was clearly audible. By following this flight noise on several consecutive days, a drone congregation area (DCA) was located under the canopy of a high emergent tree. There, the drone's hum was regularly heard at the expected time and several A dorsata drones were caught. Under the canopy the drones were attracted to a queen dummy impregnated with queen pheromone. Dummies outside the canopy or above the tree did not attract any drones. Further, drone attractivity showed a clear maximum several meters below the canopy. Under the canopy of other emergent tall trees three more DCAs were detected. At another place one observation on a slope of a mountain resulted in the detection of a DCA downhill in the valley. No drones were found under tall trees on the slope. In A mellifera and A cerana the factors that cause the drones to congregate at a distinct place are still unknown. So, the clear feature of the A dorsata DCA in Borneo involving a landmark is unique. Observations from other parts of the extended natural distribution of A dorsata in Asia are required to confirm whether the drones of this species generally congregate under the canopy of emergent tall trees

Paternity skew in seven species of honeybees (Hymenoptera: Apidae: Apis)

Honeybees (Apis) show an extremely polyandrous mating system. In general honeybee queens mate with at least ten drones. The reproductive success of the drones is usually biased giving rise to speculations of a first or last male advantage. Especially for A. andreniformis and A. florea a first male advantage was hypothesized due to the peculiar anatomy of their male genitalia. We reanalyzed data from the literature by using a sample size calibration method to survey the differences and similarities in paternity skew among species in the genus Apis. The paternity skew among seven honeybee species differed significantly, particularly due to the rare patrilines. The sorting algorithm, i.e. the ranking of the patrilines, had, however, a considerable effect on the paternity skew pattern. The frequent patrilines appeared to be similarly distributed in all tested species. As a consequence the proposed first male advantage in the dwarf honeybees is not supported by empirical data

Numbers of spermatozoa in queens and drones indicate multiple mating of queens in Apis andreniformis and Apis dorsata.

Drones of Apis dorsata had an average of 2.46·106 spermatozoa in their vesiculae seminales. Two queens had 3.67·106 spermatozoa in their spermathecae. In A adreniformis, drones had an average of 0.13·106 and the spermathecae of 2 queens contained 0.98 and 1.09·106 spermatozoa. In both A dorsata and A andreniformis the spermathecae of queens contained more spermatozoa than the vesiculae seminales of a single drone of either species. Therefore, we conclude that multiple mating occurs in both species as is the case for A mellifera, A cerana and A florea

Evidence of reproductive isolation confirms that Apis andreniformis (Smith, 1858) is a separate species from sympatric Apis florea (Fabricius, 1787).

The species Apis andreniformis (Smith, 1858), the small dwarf honey bee of South-east Asia, is recognized as a valid biological species. This recognition is based on distinctive endophallus characteristics in comparison with sympatric Apis florea (Fabricius, 1787). Additionally, scanning electron microscope images of drone basitarsi are presented, as are preliminary comparisons of wing venation

Social Waves in Giant Honeybees Repel Hornets

Giant honeybees (Apis dorsata) nest in the open and have evolved a plethora of defence behaviors. Against predatory wasps, including hornets, they display highly coordinated Mexican wave-like cascades termed ‘shimmering’. Shimmering starts at distinct spots on the nest surface and then spreads across the nest within a split second whereby hundreds of individual bees flip their abdomens upwards. However, so far it is not known whether prey and predator interact and if shimmering has anti-predatory significance. This article reports on the complex spatial and temporal patterns of interaction between Giant honeybee and hornet exemplified in 450 filmed episodes of two A. dorsata colonies and hornets (Vespa sp.). Detailed frame-by-frame analysis showed that shimmering elicits an avoidance response from the hornets showing a strong temporal correlation with the time course of shimmering. In turn, the strength and the rate of the bees' shimmering are modulated by the hornets' flight speed and proximity. The findings suggest that shimmering creates a ‘shelter zone’ of around 50 cm that prevents predatory wasps from foraging bees directly from the nest surface. Thus shimmering appears to be a key defence strategy that supports the Giant honeybees' open-nesting life-style

‘Special agents’ trigger social waves in giant honeybees (Apis dorsata)

Giant honeybees (Apis dorsata) nest in the open and have therefore evolved a variety of defence strategies. Against predatory wasps, they produce highly coordinated Mexican wavelike cascades termed ‘shimmering’, whereby hundreds of bees flip their abdomens upwards. Although it is well known that shimmering commences at distinct spots on the nest surface, it is still unclear how shimmering is generated. In this study, colonies were exposed to living tethered wasps that were moved in front of the experimental nest. Temporal and spatial patterns of shimmering were investigated in and after the presence of the wasp. The numbers and locations of bees that participated in the shimmering were assessed, and those bees that triggered the waves were identified. The findings reveal that the position of identified trigger cohorts did not reflect the experimental path of the tethered wasp. Instead, the trigger centres were primarily arranged in the close periphery of the mouth zone of the nest, around those parts where the main locomotory activity occurs. This favours the ‘special-agents’ hypothesis that suggest that groups of specialized bees initiate the shimmering