H. R. Hepburn

Social encapsulation of beetle parasites by Cape honeybee colonies (Apis mellifera capensis Esch.)

Worker honeybees (Apis mellifera capensis) encapsulate the small hive beetle (Aethina tumida), a nest parasite, in propolis (tree resin collected by the bees). The encapsulation process lasts 1–4 days and the bees have a sophisticated guarding strategy for limiting the escape of beetles during encapsulation. Some encapsulated beetles died (4.9%) and a few escaped (1.6%). Encapsulation has probably evolved because the small hive beetle cannot easily be killed by the bees due to its hard exoskeleton and defensive behaviour.

Behaviour of African and European Subspecies of Apis Mellifera Toward the Small Hive Beetle, Aethina Tumida

SHB. We previously demonstrated that adult SHB will feed on European honey bee eggs in a laboratory setting, even in the presence of excess honey and pollen (Elzen et al., 1999). Five 0.473-litre jars were established with five adult beetles, a known number of Cape honey bee eggs in uncapped comb, and excess honey and pollen. Five control jars consisted of a known number of eggs in comb and excess honey and pollen (no beetles added). All 10 jars were held 24 h at 32°C and the number of eggs remaining were counted. Results showed overall, within 24 h the SHB ate 94% of the Cape honey bee eggs.

Small hive beetles survive in honeybee prisons by behavioural mimicry

Abstract. We report the results of a simple experiment to determine whether honeybees feed their small hive beetle nest parasites. Honeybees incarcerate the beetles in cells constructed of plant resins and continually guard them. The longevity of incarcerated beetles greatly exceeds their metabolic reserves. We show that survival of small hive beetles derives from behavioural mimicry by which the beetles induce the bees to feed them trophallactically. Electronic supplementary material to this paper can be obtained by using the Springer LINK server located at htpp://dx.doi.org/10.1007/s00114-002-0326-y.

Oviposition by small hive beetles elicits hygienic responses from Cape honeybees

Two novel behaviours, both adaptations of small hive beetles (Aethina tumida Murray) and Cape honeybees (Apis mellifera capensis Esch.), are described. Beetles puncture the sides of empty cells and oviposit under the pupae in adjoining cells. However, bees detect this ruse and remove infested brood (hygienic behaviour), even under such well-disguised conditions. Indeed, bees removed 91% of treatment brood (brood cells with punctured walls caused by beetles) but only 2% of control brood (brood not exposed to beetles). Only 91% of treatment brood actually contained beetle eggs; the data therefore suggest that bees remove only that brood containing beetle eggs and leave uninfected brood alone, even if beetles have accessed (but not oviposited on) the brood. Although this unique oviposition strategy by beetles appears both elusive and adaptive, Cape honeybees are able to detect and remove virtually all of the infested brood.

Pheromonal and ovarial development covary in cape worker honeybees,apis meffera capensis

compounds typical of the first plant species and not those of the second one. Interestingly, storage in the body is less specific [2]. Even more unexpected is the fact that O. cacaliae also feeds on Petasites paradoxus in the field, since this plant does not contain PAs in its leaves [3]. Moreover, within one field site, different plants of Adenostyles alliariae have been shown to be highly variable (from 0 to 10000 ppm PA in the dry leaves) [6]. The ability to store PAs in the body over a long period of time and to translocate them into the glands when these are emptied is clearly a way to buffer the beetle defensive characteristics and to counteract the phytochemical variability. It might even be necessary for sequestration of toxins to be an evolutionary stable defensive strategy in herbivores.

Wasp Hawking Induces Endothermic Heat Production in Guard Bees

Abstract When vespine wasps, Vespa velutina Lepeletier (Hymenoptera: Vespidae), hawk (capture) bees at their nest entrances alerted and poised guards of Apis cerana cerana F. and Apis mellifera ligustica Spinola (Hymenoptera: Apidae) have average thoracic temperatures slightly above 24° C. Many additional worker bees of A. cerana, but not A. mellifera, are recruited to augment the guard bee cohort and begin wing-shimmering and body-rocking, and the average thoracic temperature rises to 29.8 ± 1.6° C. If the wasps persist hawking, about 30 guard bees of A. cerana that have raised their thoracic temperatures to 31.4 ± 0.9° C strike out at a wasp and form a ball around it. Within about three minutes the core temperature of the heat-balling A. cerana guard bees reaches about 46° C, which is above the lethal limit of the wasps, which are therefore killed. Although guard bees of A. mellifera do not exhibit the serial behavioural and physiological changes of A. cerana, they may also heat-ball hawking wasps. Here, the differences in the sequence of changes in the behaviour and temperature during “resting” and “heat-balling” by A. cerana and A. mellifera are reported.

Production of Aerodynamic Power in Mountain Honeybees (Apis mellifera)

Correspondence to: H.R. Hepburn Although honeybees live in mountains, permanent colonies above 3000 m are rare [1]. At about this altitude reduced air density and oxygen tension, temperature and wind conspire against the high metabolic, temperature-controlled flight engine of honeybees [2–4]. As miniature aircraft operating at low Reynolds numbers, the aerodynamic power requirement increases with altitude because of reduced air density. These effects could in principle be ameliorated either by increasing power output or by a direct reduction in the aerodynamic power requirement [5]. Additional power output is precluded by the physiological inability of honeybees to deliver sufficient oxygen to the flight engine at high altitude [2–4]. Thus, a direct reduction in the aerodynamic power requirements remains the only viable hypothesis to explain how honeybees fly at the higher altitudes. Accordingly, we analysed some aircraft dimensions of honeybees (Apis mellifera) from wild native colonies along a transect from sea level to nearly 2500 m in the Drakensberg mountains of southern Africa (Table 1). Worker bees were collected in alcohol and subsequently dissected to separate the wings from the thorax and the latter from the other body parts after which all were weighed on a microbalance to constant dry weight. The four wings of each bee were slide-projected on a digitizing tablet and scanned to measure total surface area. Finally, values for wing surface area (S), whole body mass (M), wing loading (WpM/S), thorax mass (m) to whole body mass (M) ratio (rpm/M) and an excess power index (EPI) were calculated (Table 1). The excess power index (see “Appendix”), derived from the general theory of flight [5], is a measure of the maximum power available to the bee over the power required to maintain equilibrium in steady, level flight and is defined as: EPIp;(r/W). In a factor analysis using the colony means of the mass-related characters and the total wing surface area, two factors with eigenvalues greater than 1 were isolated: factor 1, head, thorax, leg and wing mass and total wing area; factor 2, abdominal mass. These two factors accounted for 90.4% of the variance in the data. The loading for each character had an absolute value greater than 0.80. The graph of the factor scores showed two clusters: colonies at altitudes of 1500–2500 m forming a cluster (1) in the right hand T bl e 1. M ea ns a nd s ta nd ar d de vi at io ns ( sd ) of w in g su rf ac e ar ea , w ho le b od y m as s, w in g lo ad in g fa ct or , th or ax /w ho le b od y m as s ra ti o an d ex ce ss p ow er i nd ex f or

The proteins of beeswax.

Honeybees construct combs from small scales of wax which they secrete. In building combs, the bees chew the scales and add a frothy substance to them [1]. The newly secreted scales and the freshly constructed combs are beeswaxes that differ in solubility [2], crystallographic and mechanical properties [3], lipid composition [4], and protein content [3]. Because beeswax is hydrophobic, it is probably transported from the wax glands to the exterior of the animal by lipophorins, a means of hydrocarbon transport known from other insects [5]. Because the lipid composition changes in the conversion of scale wax into comb [4], it is also likely that lipolytic protein is introduced into the scale wax when bees chew it. We now report on partial characterizations of these waxes which show that some proteins are unique to each wax, others are shared. The results suggest the probable origins and roles of these proteins during comb building. Freshly constructed white combs (pollen-free and without foundation) were collected from colonies of Apis mellifera scutellata and A. m. capensis; wax scales were collected directly from the wax mirrors of the latter. The proteins were extracted from the waxes with chloroform-methanol [6] and were virtually insoluble when purified. The extracted proteins [7] were solubilized directly in sample buffer, 10% (v/v) glycerol and 0.001% (w/v) bromophenol blue, in 62.5 mM Tris-HC1, pH 6.8. Native gel electrophoresis was performed on 10% acrylamide gel slabs. The resolving gel in 0.375 MTrisHC1, pH 8.8, was overlaid with a 3 % stacking gel (0.125 M Tris-HC1, pH 6.8), and the system run at 4 °C with constant current supplies of 10 mA through the stacking and 15 mA through the resolving gels. For SDSelectrophoresis the products were dis-

Dancing to different tunes: heterospecific deciphering of the honeybee waggle dance

Although the structure of the dance language is very similar among species of honeybees, communication of the distance component of the message varies both intraspecifically and interspecifically. However, it is not known whether different honeybee species would attend interspecific waggle dances and, if so, whether they can decipher such dances. Using mixed-species colonies of Apis cerana and Apis mellifera, we show that, despite internal differences in the structure of the waggle dances of foragers, both species attend, and act on the information encoded in each other’s waggle dances but with limited accuracy. These observations indicate that direction and distance communication pre-date speciation in honeybees.

Comb construction in mixed-species colonies of honeybees, Apis cerana and Apis mellifera

SUMMARY Comb building in mixed-species colonies of Apis cerana and Apis mellifera was studied. Two types of cell-size foundation were made from the waxes of these species and inserted into mixed colonies headed either by an A. cerana or an A. mellifera queen. The colonies did not discriminate between the waxes but the A. cerana cell-size foundation was modified during comb building by the workers of both species. In pure A. cerana colonies workers did not accept any foundation but secreted wax and built on foundation in mixed colonies. Comb building is performed by small groups of workers through a mechanism of self-organisation. The two species cooperate in comb building and construct nearly normal combs but they contain many irregular cells. In pure A. mellifera colonies, the A. cerana cell size was modified and the queens were reluctant to lay eggs on such combs. In pure A. cerana colonies, the A. mellifera cell size was built without any modification but these cells were used either for drone brood rearing or for food storing. The principal elements of comb-building behaviour are common to both species, which indicates that they evolved prior to and were conserved after speciation.