Bees and flies

Insects and other invertebrates are often under-appreciated even though many species perform important ecological roles to help sustain eco-systems. One such important role is pollination. Many species of flowering plants rely on insects to help them reproduce by transporting pollen from one flower to another. This is an example of a mutualistic relationship between flowering plants and insects where both individuals benefit from the exchange. The flowering plant benefits because the insect takes its pollen to another plant of the same species to help it to reproduce and as a reward the insect gets a reward of food in the form of nectar.

When we think about pollination we tend to think of bees and butterflies flying around from plant to plant drinking the nectar from flowers while transporting pollen with them to each new plant they visit but they aren’t the only insects that pollinate flowering plants. Many other insects also pollinate plants including species of beetles, moths, wasps and flies. 

Many of New Zealand’s native pollinators are quite specialised and tend to only pollinate one or a few closely related species and the survival of these species is heavily affected by habitat loss, climate change and introduced species. Habitat loss is especially an issue for specialised species because as they start losing the plants they survive on their population numbers decrease meaning there are less of them to pollinate the remaining plants. Also specialised species have to deal with competition from introduced species that can pollinate the same plants as them meaning there will be less opportunity for them to gain the food reward from the plant they pollinate. Many species are adapted to specific environmental conditions so climate change can have a huge impact on their survival because if the conditions that are ideal for their survival change too much they can die.

The relative importance of solitary bees and syrphid flies as pollinators of two outcrossing plant species in the New Zealand alpine is a paper that investigates insect pollination of flowering alpine plants which hasn’t really been studied before. It was believed that many of New Zealand’s alpine plants are autogamous meaning they self-fertilise and don’t rely on pollination which is likely because more than 70% of NZ’s alpine plants have white or near-white flowers and insects are typically attracted to brightly coloured flowers.

This paper investigated pollinator importance by measuring the amount of pollen grains deposited by on the stigma by the insect and how often the insect visited that species of plant. The results showed that Hyloeus matamoko, a species of short tongued solitary bee, was the primary pollinator of the two plant species investigated (Ourisia glandulosa and Wahlenbergia albomarginata) having done 90% of the pollinations. Syrphid flies also visited one of the plant species the same amount of times as the solitary bee but only did 10% of the pollinations meaning it was a much less important pollinator than the bee species.

Without insects around many of the flowering plants that rely on them for pollination would begin to disappear and go extinct making the world around us a bit less beautiful.