Because they are small and don’t come in big numbers, they’re often overseen and most people don’t even know of their existence.
Invertebrates curator Julia Kasper introduces New Zealand native bees, and explains why they are so important, their biggest threats, and what is being done to help.
Many people who think of a bee picture a western honey bee, Apis mellifera, cultivated for thousands of years and deliberately spread all over the world.
However, this is only one species of eight true honey bees and there is actually a very diverse group of 20,000 bee species worldwide.
In New Zealand, we have 28 native bee species – not many compared to the approximately 1,500 species in Australia.
Like honey bees, these native bees forage on flowers. While they collect nectar and pollen for food they pollinate the plants they visit. However, their life is very different from the domesticated Apis mellifera.
Burrows, not hives
Native bees are small and dark and each female burrows her own nest in the ground or hollow plant stem, where she generally lives a solitary life – unlike her bigger relatives living in hives.
The females lay approximately 8-12 eggs in their life into the small burrows and feed their larvae with nectar. Once adult females themselves, the offspring dig their own nest.
The social structures in a honey bee colony allow for splitting the work tasks. Only the queen lays eggs and the workers collect nectar and pollen, care for the offspring or protect the hive.
Their ovipositor (a tube-like organ used to lay eggs) could evolve to a stinger. Since New Zealand native bees don’t protect a colony and a honey harvest, they barely sting. The males only take part in the reproduction process.
Native bees don’t fly long distances when foraging. They stay in a radius of approximately 100 meters to their nest.
They have very short tongues that are perfect to visit and pollinate the small flowers of New Zealand’s native plants, such as mānuka and kānuka. But they are also widespread in orchards, some vegetable crops, and exotic flowers.
Meet the locals
Meet the three New Zealand genera: Leioproctus, Lasioglossum, and Hylaeus.
Leioproctus is the biggest and most common genus in New Zealand. They are 5-12 mm long and very hairy.
Normally black, there is one species that has dense yellowish hair, the South Island species, L. fulvescens.
Females of this genus dig tunnels into the ground up to 30 cm. Sometimes these burrows appear like a colony because the little entrance holes are very close to each other. When it comes to choosing the right breeding ground, the species are very picky. They can be found in specific habitats, like L. metallicus, which is a coastal breeder, but also the characteristic of the soil itself can be important, for example clay, gravel, and fine grain sand can make a big difference.
Hylaeus species are only 7–9 mm long, rather slender, and almost shiny black as they are hairless. You can recognise them by their small yellow markings on the face and thorax. Unlike their relatives, Hylaeus nest in plant material: hollow dead stems, in twigs, branches, or holes drilled by other insects in logs. They are missing the so-called corbicula on their hind legs – a pollen-carrying basket – and have no other structure to collect the pollen. Instead, they carry the pollen in the stomach.
The smallest (4–8 mm long), Lasioglossum, have only a few hairs and can appear black or greenish. This genus shows a very basic social structure as a few females can be found in one nest in the soil. Lasioglossum sordidum seems to be better adaptable to changed habitat and even chemicals. Populations have been observed nesting in farmland.
Not from around here, are you?
The intentional introduction of the western honey bee (A. mellifera) to New Zealand happened around 180 years ago, initially to produce honey and later also to improve the pollination of food crops. Western honey bees are the workaholics of all bees and are absolutely crucial for pollinating our crop plants, as well as the native plants.
The government estimates the economic value of pollination is worth $5 billion a year to New Zealand’s farming and recreational industry. In 2018, New Zealand had nearly 8,000 registered beekeepers with approximately 900,000 hives. These amazing numbers are despite the collapse of many hives since 2000 due to the Varroa mite (Varroa destructor) that was accidentally introduced during this time.
The good news: the Varroa mite does not affect natives.
Apart from the honey bee, there are 12 more species that have been accidentally or deliberately introduced.
For example, because they have a very long tongue to reach inside flowers of introduced plants, bumblebees were successfully introduced from England in 1885 to improve the pollination of red clover and lucerne.
Today, the four species of bumblebees are also important pollinators for kiwifruit, blueberries, and greenhouse tomatoes.
Only one of those four species, Bombus terrestris, is known to forage on many native plants.
Bumblebees do have a social structure but with relatively small colonies (approximately 200 bees in summer). Their nests are built in dry hollow areas, such as firewood, under houses, in walls, or abandoned rabbit burrows.
Collapsing colonies and the mānuka gold rush
Although honey bees and bumblebees provide a great pollination service, they are competitors of the native bees. The rapid increase in numbers of honey bee hives in New Zealand (despite the global collapse of hives) affects the feeding success and ecology of native insects and birds as they compete for food.
They can also have further negative effects, such as modifying habitats due to preferences towards non-native plants, and increasing risks of spreading pests or diseases from beekeeping on public conservation land.
All around the world, the awareness of the impact introduced bees has on native bees increases. New Zealand, with its isolated location, offers an environment where introduced plants and managed pollinators from Europe present a unique opportunity to study and understand pollination assemblages since their impact on the ecosystem is relatively recent.
For example, New Zealand’s indigenous forests are highly valued by beekeepers for the clean nectar and pollen sources of toxin-free high-quality mono-floral honeys, which has led to the mānuka honey gold rush and additional change of land use after human settlement.
The disadvantage of the natives lies in their solitary life – they don’t fly long distances, they don’t communicate with their relatives to utilise new sources (that we know of), and they don’t have honey as a food reserve.
Habitat loss and how you can help
However, the main reasons for the population decline of the native bees are climate change and the change of land use by us!
Intensive farming and overpopulation have led to the loss of most of Aotearoa’s native habitat. Additionally, we use herbicides and insecticides to reduce yield losses caused by pests and weeds. Unfortunately, the majority of these pesticides reach beyond targeted species and pollute air, waterways, sediments, and food.
Our knowledge of the effect on the pollination network is still poor. If not killed directly by the poison, pollinating insects, such as our native bees, may face desynchronised periods of their foraging times and the flowering and nectar production of the plants.
You can support native bees by planting native plants and trees for them to feed on, and, most importantly, buy seasonal and organic products in order to stop the spread of pesticides.