Rare bee species rediscovered near Grasslands National Park
An unusual bee species that was previously recorded in Saskatchewan during the 1950s might still be present in the province after a surprise rediscovery by Royal Saskatchewan Museum (RSM) researchers.
They recently found a specimen of the Macropis cuckoo bee (Epeoloides pilosulus) among insects collected near Grasslands National Park in 2013 during a RSM bioblitz. RSM Curator of Invertebrate Zoology Dr. Cory Sheffield said the rediscovery of this bee species in Saskatchewan is quite noteworthy.
“This is a species that was assessed as endangered species in Canada, because it was so rare, and that species is now in the process of being reassessed,” he said. “So having records from this province from the last 10 years is pretty significant from the standpoint of doing the assessment, because we now know that the species is still present within the prairies.”
It was previously collected at only two locations in Saskatchewan. One was found at Wallwort in 1942 and another at Wood Mountain in 1955. The rediscovered specimen from the 2013 bioblitz was collected close to Wood Mountain near Grasslands National Park.
This rediscovery is even more memorable for Sheffield, because he was also part of the rediscovery of this same bee species in Nova Scotia in 2002.
“At that time, the species hadn’t been seen since the 1960s,” he recalled. “So when I found it in Nova Scotia, we knew that it was not extinct, but that those were the only records in Canada that we had for probably 40-some years.”
Specimens of the cuckoo bee were recorded in Alberta, Manitoba and New Brunswick in the last 13 years. This rediscovery now adds Saskatchewan to the list of places where it might be found.
A bioblitz is a biological survey aimed at recording the variety of living species found within a designated area.
“In 2013 we had nine students stationed in different parts of the province and they put out all kinds of traps and stuff to collect insects for the museum,” he explained. “They collected so many insects that we just don’t have the people power to process all that material and identify it. So we basically keep it in jars of alcohol to preserve them and we process them over time.”
The RSM hired two students this past summer to help with the processing of insects collected during the 2013 bioblitz.
“They were pinning and labeling this material and I happened to walk by one day,” Sheffield recalled. “When I saw that one, I said that looks peculiar to me or something I don’t see that often.”
He looked at the bee specimen under a microscope along with his curatorial assistant, and they both got pretty excited about what they saw.
“There’s 300 species of bees in this province,” he noted. “If you look at enough of them, you can see subtle differences, especially if you’re using a microscope. Then the differences can really jump out. And this one certainly, despite being a small blackish-brown insect, was pretty distinctive to us. So we recognized it pretty quickly as being something unique.”
This cuckoo bee is one of only two species in the Epeoloides genus in the world, and the only one found in the western hemisphere.
It is a nest parasite, similar to cuckoo birds that lay their eggs in the nests of other birds. Cuckoo bees will deposit their eggs in the nests of Macropis bees, where the cuckoo larvae will survive on the food meant for the host bee’s offspring. These bees from the Macropis group are oil-collecting bees that are completely dependent on the oil from fringed loosestrife (Lysimachia ciliata), a native wildflower that grows in moist to wet areas.
“The loosestrife actually produces an oil inside of its petals,” he said. “So if you look at the petals really close, it has these little glands that produce a fatty oil, and that’s what this [Macropis] bee is dependent on. It mixes these fats with pollen, packs it into its nest and lays its eggs on it. This cuckoo bee actually finds those nests because of the smells of the oil.”
The survival of both these bee species are therefore directly related to habitats where the fringed loosestrife occur. These areas will include edges of rivers or lakes and wooded areas with shade, such as coulees.
“That makes the whole relationship so interesting, but also so rare and likely put all the members at risk,” he said. “You have a cuckoo, which is a nest parasite of a bee that is so specialized in its food requirements that if you were to lose or greatly reduce the number of these Lysimachia plants in an area, you would basically have an impact on both bee species involved.”
The rediscovery of the cuckoo bee near Wood Mountain in Saskatchewan is directly related to the occurrence of fringed loosestrife habitat in that area.
“In the last few years when I’ve gone down to Wood Mountain area, I have found this fringed loosestrife down there,” he said. “So to me, the significance of the [cuckoo bee] specimen from that area means that this species likely has persisted in that area since the last time it was collected.”
According to Sheffield the parasitic behaviour of the cuckoo bee is actually more common than one would expect and several groups of bees are entirely parasitic. He wrote a research paper a few years ago in which he argued that the presence of cuckoo bees was indicative of healthy ecosystems.
“If populations of that oil-producing plant are lost locally or reduced greatly, then those flowers are not going to be able to support as large a population of a host bee,” he explained. “A cuckoo bee needs certain numbers of its host bee to support it. What I argued in that paper is that when you have abundant and diverse cuckoo bees within ecosystems, it is probably showing us the ecosystem is quite healthy compared to ones that don’t have cuckoo bees, because cuckoo bees probably are the first group of bees to respond to changes in the habitat quality.”
Now that the rediscovery has confirmed the presence of the cuckoo bee in Saskatchewan, the RSM will continue to look for more specimens.
“The species has seldom been photographed live,” he said. “So it would be nice to look for it in other areas to see how widespread it could be, because we know it potentially could be very widespread in the province, but just uncommon.”
This rediscovery in Saskatchewan is very timely, because Sheffield is involved in writing a new status report for the Committee on the Status of Endangered Wildlife in Canada about the Macropis cuckoo bee.
“So finding the recent record in Saskatchewan will then mean that when we do the new assessment, it will probably initiate some measures to help protect it,” he said.