Leioproctus, the hairy colletid bee,[2] is a genus in the plaster bee family Colletidae. Its members are primarily found in Australasia and temperate South America,[3] and include the most common native bees in New Zealand.[4]
Leioproctus female on Haemodorum species in Western Australia
Description
Species within the genus Leioproctus are small, black, hairy bees ranging from 4 –16 mm. Most are less than 10mm, but the largest species Leioproctus Muelleri reach up to 16mm.[5] The legs and thorax are covered in hairs ranging from black to red to yellow to white, although hair colour typically fades with age. The dorsal surface of the abdomen is mostly hairless showing the shiny black cuticle underneath. The clypeus and supraclypeus are typically hairy while the forehead is often mostly hairless, likely to avoid interference with the ocelli. Supraclypeus is almost completely flat and is densely punctured throughout.[6]
Females can be distinguished from pollen clumps, carried externally on scopae.[6]
Ecology
General diet
All their nutrients come directly or indirectly from pollen and nectar. Pollen is the main source of protein, required for growth, so it is consumed mostly during the larval stage, while nectar provides sugar, which provides the energy adults and larvae need throughout their life.[7]
Most species show medium degrees of specialisation for native flowering plants and trees. However, they multible species in New Zealand have been recorded visiting kiwifruit flowers,[6][8] and agricultural studies have caught them in clover pastures and orchards.[9] This plasticity varies between species as some studies have shown to be more willing to feed from introduced species than others.[6][8]
Foraging behaviour
Leioproctus species show almost no territorial behaviours, and often nest and feed within close proximity of each other. They can show a range of distance and foraging time between individuals as well as species. Although a common theme to all species is that they typically nest close to a large food source (<10m) such as a large Leptospermum tree (Mānuka) which are common in New Zealand and east Australia.[10]
Pollination
Most species are somewhat specialised often to a particular genus or family, which is beneficial to plants as specialised pollinators increases the likelihood of pollen being spread to the correct species.[11]
The males are relatively short lived and have little impact on pollination, but the females intentionally collect pollen by accumulating pollen in the hairs around the head and thorax while feeding on nectar before moving it to the scopae.[8] This morphology allows pollen to be more effectively spread between flowers than other potential pollinators such as other insects and birds.[12]
Leioproctus are particularly important pollinators for many endangered native plants, such as rare Proteas in Australia, many of which are strictly self-incompatible and rely on pollinators for survival. Multiple studies on Persoonia (geebungs) found that Leiproctus was the most common genus of pollinators at their study sites.[13][14] Lots of these species live in dry woodlands on acidic sandy soils that are suited to Leioproctus as they are mining bees and can tolerate these harsh environments.[14]
In New Zealand, Leioproctus are the largest genus of bees and are the next most common after Apis and Bombus. Both these genera are more efficient than Leioproctus at pollinating but they prefer introduced species over natives, making Leioproctus and other native bees still vital to native forests.[15] Research has gone into using native bees for commercial pollination and found positive results and successful trials of nest removal and re-establishment.[16] Because they nest individually, they would be more resistant to spread of disease, like Varroa mites or AFB, which is of increasing interest in agriculture.[17]
Impact from introduced honeybees
The effect introduced bees have had on native plants and bees is still unclear, but some ecologists have concerns about the effect being negative.
Introduced honeybees have been recorded visiting many of the species previously associated with native bees. For most native plant species this is atypical and unintentional of beekeepers, but due to the high demand for Mānuka honey, Leioproctus bees are now seeing high competition in some places. Because domestic honeybees live in mobile hives, beekeepers can move these hives into high resource areas and then remove them once the nectar and pollen are depleted, forcing the sessile leioproctus bees to travel far distances to find resources. Although Leiproctus species feed from species other than Mānuka, many still rely on this food source to support them over the summer, so this increased competition could reduce leioproctus populations which could then affect the other native plants they pollinate.[18]
Habitat
Leioproctus are solitary mining bees. They can tolerate a high range of substrate provided there is sufficient food resources nearby. This can range from forest undergrowth to roadside ditches to sandy costal banks to even currently occupied termite nests in at least one Australian species.[19]Leioproctus need warm temperatures (at least 15°C) before leaving their nest, typically waiting until the nest entrance is bathed in sun. Because of this, most nests face towards the north, or if in flat ground, will be well exposed to maximise heat absorption.[6]
They prefer dry ground and will often dig horizontal tunnels in banks and cliffs. Their nests are not lined with water repellent coatings, as seen in other bee nests, but nest architecture shows they can also make sink traps, potentially to prevent water from entering cells, suggesting they can tolerate wet environments.[20] This tolerance to wet conditions has been observed in multiple studies where as long as it was reasonably warm, bees would be seen, no matter the rainfall.[6]
Life cycle
Leioproctus are solitary, meaning all every female is fertile and creates their own nest for their young.[18]
Leioproctus overwinters as diapausingprepupae in cells before they pupate and begin appearing in spring or early summer. Males typically appear first closely followed by females. Immediately they mate and the females begin nest mining while the males continue breeding. The males soon die while the females finish their nests and start producing cells. Larvae require a lot of pollen and nectar to grow and survive to adulthood, and the females have a lot of environmental pressures, so most only make 10-30 cells in their 6-8 week adult lifetime, before perishing. After the eggs are laid, the larvae hatch around 72 hours later and consume all stored food over the next 10 days, then over the next few weeks become prepupae and diapause until the following spring.[6][18]
New Zealand
Distribution map of iNaturalist Leioproctus spp. sightings in NZ.
Diet
Native New Zealand Leioproctus species primarily forages on the flowers of native species in the Myrtaceae family, such as Pōhutukawa (Metrosideros excelsa), Kānuka (Kunzea ericoides) and Mānuka (Leptospermum scoparium). But some species also show plasticity for introduced species, like certain fruit trees and pasture plants.
Biogeography
At least 18 species of Leioproctus can be found across New Zealand.[21]
Australia
Distribution map of iNaturalist Leioproctus spp. sightings in Au.
Diet
Native Australian Leioproctus species forage on the flowers much wider range of native species such as Persoonia (geebungs) in Family Proteaceae[14] and many legumes such as Daviesia[20] and Acacia,[22] in Family Fabaceae. Mānuka and other Myrtaceae family flowering trees are also visted by some species.
Biogeography
More than 80 species of Leioproctus can be found across Australia.[23]
South America
Screenshot from GBIF of the Distribution map of Leioproctus spp. sightings in South America.
Diet
Research and information on Leioproctus species found in South America is seriously lacking. In New Zealand and Australia Leioproctus feed primarly on species within Family Proteaceae, Fabaceae and Myrtaceae. Between these three families there are over 3,000 species in South America, so Leioproctus feeding behaviour is likely similar to New Zealand and Australian species, although this cannot currently be confirmed.[24]
Biogeography
More than 60 species of Leioproctus can be found across South America.[25]
^Newstrom-Lloyd, L. E. (2013). Pollination in New Zealand. Ecosystem services in New Zealand—conditions and trends. Manaaki Whenua Press, Lincoln, 408-431.
https://oldwww.landcareresearch.co.nz/__data/assets/pdf_file/0008/77057/2_11_Newstrom.pdf
^ abcFale, G. (2023). Competition between native bees and honey bees on mānuka flowers in New Zealand (Doctoral dissertation, The University of Waikato). https://researchcommons.waikato.ac.nz/server/api/core/bitstreams/cc490f66-c119-4bf6-b8f4-994eb757b934/content
