Fatty acid composition of the parasitic mite Varroa destructor and its host the worker prepupae of Apis mellifera

The present study analyzes the fatty acid (FA) profile of lipids isolated from Varroa destructor Anderson & Trueman, a parasitic mite of the honey bee (Apis mellifera L.), uninfected and infected worker prepupae of the Carnolian subspecies Apis mellifera carnica Pollmann, and bee bread fed to the worker brood. Significant differences are observed in the FA profiles of lipids isolated from parasites, hosts and bee bread. Parasitism by V. destructor (henceforth, varroosis) induces visible changes in the lipid profile of worker prepupae. In infected prepupae, the percentage of total saturated FAs is lower and the percentage of unsaturated FAs is higher than in uninfected insects. These differences result from significant changes in the percentages of FAs that are most abundant in the evaluated groups (i.e. C16:0, C18:1 9c, C18:2n‐6 and C18:3n‐3 FAs). In mites and in uninfected and infected prepupae, the predominant FAs are oleic acid (41.07 ± 2.26%, 42.79 ± 1.21% and 45 ± 0.20%, respectively) and palmitic acid (22.62 ± 0.87%, 39.48 ± 0.43% and 36.84 ± 0.22%, respectively). Highly significant differences in FA composition are noted between bee bread and worker brood. The results suggest specific mechanisms of FA uptake, accumulation and metabolism in the food chain of this parasitic association, beginning from the food processed by nurse bees for larval feeding, through host organisms (worker brood) to V. destructor mites.     

Polymorphic microsatellite loci in Allodapine bees for investigating the evolution of social behaviour

Allodapine bees provide extraordinary systems for investigating the evolution of cooperation and particularly the division of reproduction in animal societies. We present the first microsatellite primers for two native Australian species (Exoneura nigrescens and E. robusta; Hymenoptera: Apidae: Xylocopinae) which allow the accurate determination of pedigrees, reproductive skew and relatedness in colonies. Up to 55 different alleles were observed per locus.     

Fine structural localisation of acetylcholinesterase activity in the compound eye of the honeybee (Apis mellifica L.)

Summary Acetylcholinesterase (AChE) activity was demonstrated histochemically at the electron microscopic level in the compound eye of the worker bee (Apis mellifica L.) by use of the method of Lewis and Shute (1969).All photoreceptor axons (short and long visual fibres) display AChE activity. The reaction product is located in the axoplasm and at the plasma membrane. Substantial amounts of the reaction product can be detected in the intercellular spaces between the visual fibres. Along the visual fibres, the enzyme activity is unevenly distributed. High AChE activity is present in the distal parts of the axons, in contrast to lower enzyme levels in the lamina. However, AChE is also present in the proximal terminals of the visual fibres as well as in the intercellular spaces between visual fibre terminals and the postsynaptic neurones (monopolar cells). Intracellular enzyme activity is almost absent in the monopolars.The authors assume the high AChE activity in the visual fibres to be indicative of acetylcholine as the transmitter at the first synapse of the compound eye. This hypothesis is discussed in view of the results of autoradiographic, electrophysiological and pharmacological investigations of the compound eye and of the ocellus. Our data are at variance with results of studies on the eyes of Diptera.     

Sterol utilization in honey bees fed a synthetic diet: Effects on brood rearing

The dietary sterols, cholesterol, campesterol, sitosterol, stigmasterol and 24-methylenecholesterol, were tested for their ability to support brood rearing in the honey bee, Apis mellifera L., by adding them singly to a chemically-defined worker bee diet. Diet supplemented with 24-methylenecholesterol supported the greatest survival of worker bees, but diet supplemented with either 24-methylenecholesterol or cholesterol supported the production of nearly equivalent amounts of sealed brood and more than any of the other three sterols tested. Diets containing stigmasterol, sitosterol, campesterol, or no supplement produced less sealed brood, in decreasing order.     

Small and Large Bumblebees Invest Differently when Learning about Flowers

Media player

PRESCOTTIELLA,A NEW GENUS OF ASYMMETRICAL DESMIDS (CHLOROPHYCEAE)1

Bipolar asymmetry has been considered a morphological characteristic sufficient for differentiation of genera among the Desmidiaceae. Therefore, Micrasterias sudanensis Grönbl., Prowse & Scott, the only species of Micrasterias showing such asymmetry, is made the type of a new genus, Prescottiella, gen. nov.     

Regulation of oogenesis in honey bee workers via programed cell death

Reproductive division of labour characterises eusociality. Currently little is known about the mechanisms that underlie the ‘sterility’ of the worker caste, but queen pheromone plays a major role in regulating the reproductive state. Here we investigate oogenesis in the young adult honey bee worker ovary in the presence of queen pheromone and in its absence. When queen pheromone is absent, workers can activate their ovaries and have well-developed follicles. When queen pheromone is present, even though workers have non-activated ovaries, they continually produce oocytes which are aborted at an early stage. Therefore, irrespective of the presence of the queen, the young adult worker ovary contains oocytes. By this means young workers retain reproductive plasticity. The degeneration of the germ cells in the ovarioles of workers in the presence of queen pheromone has the morphological hallmarks of programmed cell death. Therefore the mechanistic basis of ‘worker sterility’ relies in part on the regulation of oogenesis via programmed cell death. Our results suggest that honey bees have co-opted a highly conserved checkpoint at mid-oogenesis to regulate the fertility of the worker caste.