Adult worker honey bees alter their behaviour with age but retain a strong reliance on sensory information from the antennae. The antennae house a diverse array of receptors, including mechanoreceptors, hygroreceptors, olfactory receptors, and contact chemoreceptors, which relay information to the brain. Antennal sensory neurons that project to the antennal lobes of the brain converge onto second-order interneurones to form discrete spheres of neuropil, called glomeruli. The spatial organisation of glomeruli in the antennal lobes of the honey bee is constant, but the central distribution of information from receptors tuned to different sensory modalities is unknown. Here we show that the glomerular neuropil of the antennal lobes undergoes constant modification during the lifetime of the adult worker bee. Changes in morphology are site specific and highly predictable. The total volume of the glomerular neuropil of the antennal lobe increased significantly during the first 4 days of adult life. Each of the five readily identifiable glomeruli examined in this study exhibited a unique pattern of growth. The growth of two of the five glomeruli changed dramatically with the shift to foraging duties. Furthermore, significant differences were identified between the antennal lobes of bees performing nectar- and pollen-foraging tasks. The highly compartmentalized nature of the antennal lobes, the ease with which specific glomeruli can be identified, and the predictability of changes to the antennal lobe neuropil make this an ideal system for examining the mechanisms and behavioural consequences of structural plasticity in primary sensory centres of the brain.

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There are two microchiropteran bat species in New Zealand: the long-tailed bat Chalinolobus tuberculatus and the short-tailed bat Mystacina tuberculata. Both species coexist on Little Barrier Island in the Hauraki Gulf, New Zealand. In this study we examined the diet of M. tuberculata, and the activity levels of both bat species associated with Metrosideros excelsa, a native¯owering plant and potential nectar source, on Little Barrier Island. Between November 1994 and February 1996, M. tuberculata were caught in mist-nets, and their faecal pellets were collected for later dietary analysis. In addition, pollen samples were collected from the fur of bats caught during December 1995 and January 1996. Faecal analysis showed that M. tuberculata on Little Barrier Island exhibits a high degree of omnivory, with its diet comprising¯ying and non-¯ying arthropods, and also pollen and other plant material. During December 1995 and January 1996, the activity levels of both bat species associated with¯owering and non-¯owering M. excelsa trees were investigated by recording bat echolocation calls with automatic detecting and recording units. Signi®cantly higher numbers of M. tuberculata echolocation calls were recorded near¯owering M. excelsa trees than near non-¯owering ones, whereas the numbers of C. tuberculatus calls did not differ signi®cantly between owering and non-¯owering trees. These results contribute further to the existing evidence for nectarivory in M. tuberculata.

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