A population ecological host- parasite model is used to evaluate the potential impact of clonal parasitic laying workers of the Cape honeybee, Apis mellifera capensis on populations of Apis mellifera scutellata host colonies in apiaries and in the wild. The model includes three basic life history parameters: reproductive rate of the host colonies, transmission efficiency of the parasite and the death rate of parasitised colonies. The population dynamics of host and parasites are computed for 100 generations after an initial infestation with parasitic workers. The model reveals that infestations are likely to be fatal for apiary populations irrespective of beekeeping activities compensating for colony losses due to parasitation. Wild A. m. scutellata populations are however less likely to be affected by parasitic laying workers and stable equilibria between host and parasite occur over a wide range of the parameter space. Although it is unlikely that the parasitic clone represents a threat to the conservation of biodiversity, even low frequencies of parasitic A. m. capensis workers in wild honeybee population can cause a permanent threat to beekeeping activities.

Introduction The queen is usually the only reproductive female in the honeybee colony (Apis mellifera L.). Although workers do possess developed ovaries, these are not activated because of the suppressive pheromone signals secreted by the queen. In many studies the queen's mandibular gland secretions were found to be instrumental in worker ovary suppression (Butler, 1959, Butler and Fairey, 1963; Velthuis, 1970; among others). The pheromone of the queen mandibular secretions (QMS) are a complex bouquet of compounds dominated by a variety of fatty acids most of which have been identified and studied in detail (Winston and Slessor, 1992). Workers also produce a mandibular gland secretion, but with a fatty acid composition that is distinctly different. The dominating compound of the QMS is 9-oxo-(E) 2-decenoic acid (9ODA) which makes up about 60% of the total secretion. The worker mandibular gland secretion however is dominated by 10hydroxy decanoic acid (10HDAA) and 10-hydroxy-(E) 2dece

Abstract – Thelytokous Apis mellifera capensis workers recently brought into regions occupied by the arrkenotokous African bee A. m. scutellata, parasitise these colonies, causing colony death. These capensis workers are genetically almost identical and are referred to as a ‘pseudo–clone’. We surveyed 120 scutellata colonies, 27 in detail, at various stages of usurpation by the pseudo-clone. The scutellata queen could co-exist with egg-laying pseudo-clones for 50+ days in one case but disappeared 1–15 days in three other cases. Despite the presence of emerged queen cells no new adult queens of either race were observed in usurped colonies. Only 11 ± 13 % of the pseudo-clone population had fully active ovaries, suggesting ovarian development is inhibited in the majority of the pseudo-clones. Only 2.7 ± 1.7 % of the foraging force were pseudo-clones. The data were modelled and showed the rapid (56–105 days) growth of the pseudo-clone population and colony death over a wide range of initial conditions.