Open Access

Sampling of day-active invertebrates visiting the flowers of Grey Mangrove Avicennia marina subsp. australasica (Walp.) J.Everett (family Acanthaceae) was undertaken at a study site on the Harrington estuary, northern New South Wales, Australia. The study extended over a 4 season period (from 2016 to 2020), with more than 170 anthophilous species being recorded. Nearly all were observed contacting flower stigmas and/or anthers during foraging episodes. At least 113 of the approximately 168 species examined for pollen loads, carried Avicennia pollen. None carried mixed pollen loads, indicating foraging constancy/fidelity. Although pollen carriage does not automatically assign the status of pollinator, nevertheless, the findings indicate Avicennia marina is pollinated by a taxonomically diverse suite of native invertebrates which sit within an assemblage of flower visitors that may include non-pollinating species. Although the invasive honeybee Apis mellifera was seasonally common during most days of observation, it was uncommon or absent on some days. The occurrence of native flower-visiting species was often found to be episodic, with many species being abundant during one day or season of observation, but then absent or rarely encountered at other times. Such behavioral events highlight the need for extended periods of field investigation to illuminate more fully the pollination ecology of individual plant species. Comparison with additional anthophilous insect records from a previous 1990 – 1994 study in an adjacent littoral rainforest community, indicated that this community may furnish a pool of native insects from which Avicennia marina can seasonally recruit a dynamic pollinator network.

Australian subtropical rainforests and plant populations have become increasingly fragmented since European settlement. Managing relict populations and remnants within the landscape matrix is dependent upon our understanding of plant reproductive biology. The incidence of autogamous self-compatibility and dioecy was investigated in subtropical rainforests, near Taree, in the Manning Valley (northern New South Wales). The proportion of dioecious species in rainforests of the region is high (~17%), but varies among sites. The potential for hermaphroditic species to self-pollinate was examined by bagging inflorescences in the field. Of the > 30 species (in 14 families) studied, nine species exhibited high levels of selfcompatibility. These were predominantly pioneer and edge species, but other pioneer species were self-incompatible. Different behaviour occurred within families. Twenty species (in 13 families) regenerated from basal coppice or root suckers following bushfire. The significance of knowledge of reproductive biology for management is discussed.

Insects visiting flowering trees of Syzygium floribundum, Syzygium smithii and Tristaniopsis laurina (Myrtaceae) were recorded in lowland subtropical rainforest communities in the Manning Valley, mid-north coast of New South Wales. These species are visited by a taxonomically broad assemblage of insects, many of which are known to frequent other rainforest- and open forest-flowering plant species. Consequently there is likely to be a regional pool of potential pollinators found throughout the range of each plant.