The Foraging Behaviour of Honeybees on Ornamental Malus Spp. used as Pollinizers in Apple Orchards

Abstract

The losses which can result from devoting a proportion of the acreage of an orchard to relatively uneconomic pollinizer trees interests growers in having pollen sources grafted into the trees of the main cultivar. The possibilities of using ornamental Malus spp. in this way are being investigated. They have several advantages over more conventional pollinizer cultivars: e.g. some species produce more flowers and hence more pollen per unit length of wood (Church, Goodall & Williams 1974), and the small fruits are readily distinguishable from the main crop at harvest. Although many insects will pollinate apple flowers (Kendall & Solomon 1973; Kendall 1973) there are frequently too few present in commercial orchards (Williams 1970; Smith & Lewis 1972). Honeybees are undoubtedly the most numerically important pollinators, particularly in orchards where colonies are introduced at blossom time. Consequently, the behaviour of honeybees in response to new management practices such as the introduction of ornamental Malus pollinizers is of interest and importance. The structure, presentation, colour and scent of the flowers of many ornamental Malus spp. are quite different from those of 'Cox's Orange Pippin' and other dessert apple cultivars. Hence, particular attention is given here to the relative attractiveness of their flowers to honeybees and the tendency of bees to remain constant to these species during a foraging trip. Both these aspects of bee behaviour can affect the transfer of pollen from one variety to another in apple orchards (Free 1960, 1963; Free & Spencer-Booth 1964; Free 1966). Three ornamental Malus spp. (M. aldenhamensis, M. floribunda Hillierii and an un-named species M. cv. Golden Hornet) are included in the present study because from observations on time of flowering, pollen quantity and quality (Wilson & Williams 1972; Church et al. 1974) these appear to be suitable as pollinizers for 'Cox'; and their flowers differ, particularly in colour, being crimson, pink and pinkish white respectively, so that any behavioural responses by honeybees to different flower structures or colours could be assessed.