Are moths the missing pollinators in Subantarctic New Zealand?

Abstract

On offshore islands, flowers are typically small, simple in colour and shape and more reliant on wind- or self-pollination than insect-mediated pollination. Islands also tend to have a species-poor pollinating fauna. The New Zealand Subantarctic islands (latitude between about 46° and 60°) have a depauperate pollinator fauna. However, many flowers in this region are large, brightly coloured and apparently completely reliant on insect visitors for pollination. In the absence of bees and butterflies, moths and flies may be particularly important pollinators in the region. Using six Heath moth traps simultaneously over four nights in three different habitat types, 241 moths were caught, representing six species. We found that moths carried pollen identified to four plant species (Bulbinella rossii, Dracophyllum longifolium, Gentianella concinna and Acaena minor), with B. rossii and D. longifolium pollen being most abundant on moth bodies. Weather conditions explained moth abundance and distribution, but neither weather nor the number of moths caught were reliable predictors of their potential as pollinators; moths carried on average more pollen grains from more plant species in the shrubland despite harsh weather conditions and few individuals caught. Local flowering abundances may help explain this trend, with the predominance of D. longifolium flowering in the shrubland and B. rossii in the exposed megaherb field. This study is the first to provide evidence that moths may be capable of acting as pollinators in Subantarctic New Zealand, and that their contribution should not continue to be overlooked.

Keywords

• pollination
• islands
• interactions
• lepidoptera
• ecology
• mutualism