A few miscellaneous arthropods from 2023.
Arthropod Miscellany – 2023
Category: Hymenoptera
Osmia taurus – Taurus Mason Bee
Casey and I found these mason bees in mid April this year at Hughes Mountain N.A. I had no clue what these were but was intrigued to “discover” a new-for-me bee so early in the season. Unfortunately, I was to find out it is yet another introduced species. Apparently these were first found in Maryland in the 1970’s and have spread west since then.
Photographic Observations of a Communal Nesting Sweat Bee (Agapostemon virescens)
For the past few years I have noticed a good number of native bee nest holes along exposed sections of bare soil at one of my favorite hiking and nature observation sites – August G. Beckemeier Conservation Area in St. Louis Co., MO. This past spring I finally decided to make this a project and set about a quest to make some images of these gals provisioning their nests. As usual, I wound up learning along the way.
As is commonly known, many of our native bees are solitary and nest without close contact or cooperation in regards to conspecifics. At the opposite side of this spectrum of sociality in the Hymenoptera are most species of bumble bees and the honeybee. These bees are considered truly social, or, eusocial. The characteristics necessary to be considered a eusocial species are 1) cooperative care of offspring of others within the colony, 2) overlapping generations within a colony of adults, and 3) a division of labor into reproductive and non-reproductive groups. Many of our bee species lie somewhere between these two extremes. The bee of focus here, Agapostemon virescens, lies early in the area we call being presocial, aka parasocial.
Let’s clarify the differences between a presocial species such as A. virescens and the eusocial honeybee. The honeybee shows all three necessary characteristics of a eusocial species. The individual workers obviously care for brood that are not their own – they don’t even have offspring of their own, instead spending much of their lives caring for the offspring of their queen (sisters). They have multiple overlapping generations within the hive in a particular season, as well as across multiple seasons and as just mentioned, there is a division of labor into reproductive and non-reproductive castes. A. virescens on the other hand, is not nearly as cooperative. Individuals of this species share basically just a front door to their brood chambers and nothing more. After entering the communal nest, each female builds their own brood sub-chamber cells and each provisions their own by processing pollen into cakes and leaving them in their respective brood chambers. There is no brood care after the egg is deposited and the sub-chamber sealed. The offspring then emerges later in the summer.
So, what are the pre-conditions necessary for the eventual development of more complicated forms of sociality, i.e. eusociality? Or more directly, what advantages are there in adopting more of a social lifestyle if we assume the starting point was a solitary existence? Scientists consider two important pre-conditions need be met for the evolution of eusociality. First, the species offspring must be altricial, or require a great amount of parental care in order to reach maturity. Second, there need be low reproductive success rates of solitary pairs that attempt to reproduce. Here is what is believed to be the primary driver that pushed A. virescens into this presocial condition.
Kleptoparasitism is where one animal takes advantage of the hard work of another by taking their prey or collected foods. In this case, we are primarily concerned with the large group of bees known as cuckoo bees. Kleptoparasitism has evolved numerous times in the Hymenoptera and cuckoo bees lay their egg on or near the host’s provisions. The parasite will hatch first and eat the host’s pollen and will often kill and eat the host’s larvae as well. With such an obviously successful reproductive strategy, it should come as no surprise that there would be a strong selective advantage of finding ways to thwart these parasites. In the case of A. virescens, evidence suggests that by communal living as described here, the rate of kleptoparasitism is much lower when compared to related species that have the completely solitary reproductive strategy.
I guess the obvious next question is how in the world could eusociality evolve from this state? This is a fascinating story that involves terms like kin selection, altruism and haplodiploidy. It also involves a good deal of math and explanation from some of the greatest evolutionary thinkers since the time of Darwin (read anything by William D. Hamilton for example). It is also well out of the scope of this piece. But, I hope it is clear that before getting near the high rung of eusociality on this ladder, that a small first step like seen in this example would be necessary.
I hope I got most of this correct enough. It’s been a long time since I took Zuleyma Tang-Martinez’s Evolution of Animal Sociality class at University, which I thoroughly enjoyed. Please feel free to leave a comment to correct or clarify or ask a question.
Much of what I covered here and a lot more can be found in Malte Andersson’s The evolution of eusociality (Ann. Rev. Ecol. Syst. 1984. 15:165-89
The evolution of Eusociality
Myrmecochory – Dicentra cucullaria (Dutchman’s breeches)
In continuing my work from last year, this year I was able to capture a few Aphaenogaster rudis moving the diaspores of Dicentra cucullaria (Dutchman’s breeches). Although this was the best year I’ve ever seen for D. cucullaria, getting everything to work just right in order to photograph this process was difficult. I was often short on the time needed to do this. Also, the cool temps we had this spring made it a bit difficult to find the foraging ants, even when the supply of diaspores I had at my disposal were ample.
-OZB
Myrmecochory – Seed dispersing ants!
Myrmecochory is a term that comes from Greek, created from “myrmeco” – of or pertaining to ants, and “chory” – plant dispersal. It is one of approximately seven plant “dispersal syndromes” classified by ecologists, is found in approximately 5% of the angiosperms and occurs in numerous ecosystems around the world.
Mutualism is thought to be the basis for this dispersal syndrome. Although this is not necessarily crystal clear, the ants are attracted to the eliasome – the fleshy structure attached to the seed that is a rich source of lipids, amino acids and other nutrients. The ants typically will move the diaspore (eliasome + seed) back to their nests. Dispersal distances vary, but are generally not great – most often 2 meters or less. However, for small forbs this distance is often adequate for moving these propagules outside the range of competition of the parent plant.
Distance dispersal is not the only selective advantage that plants gain from this mutualistic relationship. When the ants have moved the seeds to their nests, they remove the eliasome to feed their young and typically dispose of the seeds in their midden heaps or eject them from the nest. Seeds that are moved to midden heaps or other such locations benefit in multiple ways. First, they are placed in microenvironments that are conducive for germination and early growth. They are protected from heat of fire that could destroy the seeds and benefit from not being accessible to birds and other seed predators. This is referred to as ‘directed dispersal.’ Some studies have shown that the removal of the eliasome may promote germination, similar to the process of seed being removed from their fleshy fruit as it is passed through the gut of a vertebrate.
Their is typically no specialization of particular ants dispersing a particular plant species, with almost any ant species being ready to take advantage of a free meal. The possible exception being that larger diaspores must be dispersed by larger ant species.
My hope was to photograph myrmecochory across a variety of species this year. I was fortunate to find success with Sanguinaria canadensis but had no luck in my attempts with Dicentra cucullaria (dutchman’s breeches). I tried hard for trillium species as well but discovered the plants I was waiting for mature fruits for weeks were being harvested most likely by SNR staff. I will be trying for these again in the future and hope to photograph prairie species as well.
The fruits of Stylophorum diphyllum (celandine poppy), I discovered, had a much smaller window of ripening. I had to check at least every two days or I would miss the opportunity of a large fruit full of diaspores.
See below for my attempts at filming myrmecochory. This was definitely challenging. I had troubles predicting the ants’ behavior, especially while under the bright, continuous lighting needed for high-magnification photography such as this. Something else to try and improve upon next year.
I’d like to thank James Trager for his assistance with ant species identification.
-OZB
The interesting and important Spring Beauty (Claytonia virginica)
Until this spring, I assumed that spring ephemerals, like Claytonia virginica (spring beauty) and others that begin flowering in early spring, did not provide much sustenance for early season pollinators. For no reason in particular, I assumed that most of these plants preferred selfing versus providing the resources to attract insect pollinators.
After taking a closer look at the blankets of C. virginica that lie on the slopes of Beckemeier Conservation Area near our house, my eyes were opened. I found pollinators everywhere on multiple trips during this long and cool spring. Unfortunately many species were so quick that they eluded me and my camera. However, I managed to nab a few of the more cooperative and with some help of those smart folks at BugGuide.Net, I got as close to the right identifications as I could.
Have you heard of oligolecty? Until doing this research, I had not either. Oligolectic is a term that describes certain bees species that have specialized preference to pollen from only specific plant groups – plants from a small group of genera, a single genus, or in this case, one single species.
The spring beauty bee (Andrena erigenidae) is a mining bee (Andrenidae) that feeds exclusively on the pollen and nectar of C. virginica. In fact, the larvae of this species cannot grow optimally on any other pollen source. So, it may not come as a surprise that this was the most common bee I found foraging on the fields of spring beauty.
These mining bees will take the pollen during a flight run that may last up to more than an hour and then bring it back to their self-constructed nursery hole in the ground. There they will turn the pollen into cakes and lay a single egg on each. This will be all the material needed for an individual larvae to develop into an adult.
The next pollinator is a bee from the same genus, Adrena. This is a huge genus, comprised of more than 450 species in the U.S. Most often they are impossible to identify to species without having the bee in-hand and available for close inspection.
This beautiful and hairy ginger was considerably larger than the previous Andrena. I estimate this bee was about two-thirds the size of the domesticated honeybee.
I’m not sure if this individual was a male, or if it was only interested in getting nectar, but I never saw this species actively collecting pollen from C. virginica.
The long tongue on this one will allow for it to collect nectar from a larger variety of flowers, while the hairs on this bee definitely help it meet its pollinator status.
I found a couple cuckoo bees foraging amoung the C. virginica as well. This “nomad cuckoo” pictured below is a cleptoparasite, meaning the female will lay its egg inside the nest of a different host species. The cleptoparisitc larvae will hatch first and will often kill the eggs or larvae of its host and then use the pollen provisions the host mother left to complete its development. This particular genus, the Nomada, is known to primarily use species in the above discussed Andrena genus as its host.
The cuckoo wasp, like this metalic green beauty in the Chrysididae family are also cleptoparasites that likely will use Adrena bees as hosts.
Bees and wasps were not the only pollinators I found on spring beauty. I also found a couple species of ants (not pictured because they never stand still long enough) and a couple of dipteran species, like this tachinid fly.
I now want to introduce what was probably the most interesting thing I learned about spring beauty this year. Having been able to work on Asian Soybean Rust for a couple years during my career, I have since been very interested in the complex life-cycles of plant rusts. I suppose due to the dense population of C. virginica at this location and the cool and wet spring we have had, I found that many plants were infected with spring beauty plant rust (Puccinia mariae-wilsoniae). With just taking a cursory estimation of the hillsides, I think that as many as 50% of this population was infected with this rust. When I took the succeeding photo ( I so wish I had taken more and better photos of this), little did I know that my investigation would take me into a complex relationship that not only involved this plant host and rust relationship, but would also involve slugs (yes slugs) and the very pollinators that enticed me to bend the knee in the first place.
I am sure that anyone who has taken the time to appreciate spring beauty more than during one season and/or place has noticed the variability in flower parts coloration. The majority of what is to follow here comes from an intriguing bit of work by Frank Frey (2004). C. virginica can vary from almost completely white to being mostly colored with pink to mauve to crimson stripes and other floral parts. Frank describes that plants that with higher levels of theses reddish pigments are preferred by pollinators and therefore, “…floral redness was associated with higher percentage fruit set.” Well then, this should beg the question, if this is the case why are there still plenty of individuals and populations of the less-fecund whitish pigmented flowers? Shouldn’t selection have taken care of this by now?
Here is where the slugs and rust comes into the story. These two, surprisingly, affect opposing selective forces on the coloration of C. virginica flowers. Plants with more white-colored flowers hold up better against predation by slugs due to the anti-herbivore properties of the flavonol pigments that produce the white coloration in these plants. In addition, for reasons that are not completely understood, the rust pathogen does better at infecting and propagating new spores on plants with redder-colored flowers. This was eye-opening for me to learn that something besides pollinator preference was manifesting a selective force on floral morphologies.
This is a highly simplified summary of the story this paper holds. I highly encourage you to check it out for yourself by following the link below.
I love the never ending stories that can be learned from a single, common and seemingly simple spring ephemeral wildflower. I’m sure that spring beauty still has a number of stories to tell. I wish I had taken more photos of the rust and I will try and see if I can find plants with telia, the next form of spore-producing legion by this rust. It occurs later in the lifecycle of the plant. I just hope I’m not too late to get it this season.
Thanks for the visit!
-OZB
Citations
Observations on phenology and pollination of Triphora trianthophora (three-bird orchid) made during the summer of 2019
This post is a modified article that was originally published in the Webster Groves Nature Study Society’s journal, Nature Notes (January, 2020, Vol. 92, No. 1).
Finding the orchid, Triphora trianthophora (three-bird orchid, nodding pogonia), during open bloom can be somewhat of a chore, particularly among us weekend warriors. Casey Galvin and I were both intrigued about the possibility of getting photographs of this diminutive and gorgeous orchid since learning of their discovery at Babler State Park by the WGNSS Botany Group led by Nels Holmberg, John Oliver and others in 2018. The following descriptions and photographs are anecdotal and were not collected using rigorous scientific methodology.
Phenology
There are several reasons it is challenging to find this extremely ephemeral plant in bloom. First, being partially saprophytic, the plants exhibit periodic dormancy and may not send up above-ground shoots every year, persisting instead as subterranean tubers for extended periods (Homoya, 1992). Even when they do produce stems and leaves, there is no guarantee the plants will flower in a given year. Additionally, when they do flower, any one bloom is open for only a few hours during a single day.
Exhibiting a phenomenon known as thermoperiodicity, a group or population of these plants are synchronized to open mature buds on the same day. This first wave of synchronous blooming is reportedly induced by a drop in minimum daily temperature of at least three degrees over two or more consecutive days. Following another 48-hour period, all mature buds within the population will then open on the same day (Luer 1975). Being skeptically minded, this was something I wanted to observe for myself.
Beginning in late July, Casey and I began monitoring the easier to get to population at Babler State Park. The first wave of synchronous flowering occurred on August 3rd. We unfortunately missed this but know the exact date because of visits on days immediately before and after this date. Looking into historical temperatures collected from the closest publicly-available weather station (Babler Park Estates – KMOBALLW37) revealed the initial blooming date fit the required temperature pattern perfectly (see attached figure). I continued monitoring and collecting flowering data and observed two more large flushes of synchronized blooms along with three days interspersed where only 3–10 stems/plants opened flowers. For subsequent synchronized days, I did not observe a coinciding drop in temperature as described above. I assume that the trigger for the initial bloom works to synchronize the population and subsequent larger bloom days are consequently synchronized due to all plants ‘running ahead’ at the same rate. However, there could potentially be some other unknown environmental triggers that are playing a hand here.
Pollination
Halictid bees have been reported to be the primary pollinator for this species (Luer 1975). I had this in mind as I observed and began taking photographs while visiting on a large bloom day but doubted I would be fortunate enough to observe or photograph a potential pollinator visit. However, patience allowed me to do just that. I first observed visits by small flies and Bombus impatiens. Although Williams (1994) reported that Bombus have acted as pollinators of this species, I did not observe any of these visitors with attached pollinia during the 10-15 flowers I watched them visit. Eventually, I observed three different Halictid bees as they visited multiple flowers and observed these were heavily attached with pollinia. As described by Williams (1994), seed capsule production (successful pollination) is a relatively rare event in this species. Nevertheless, this was a treat to observe and photograph.
REFERENCES
Homoya, M.A. Orchids of Indiana. Indiana University Press, Indianapolis, Indiana, USA.
Luer, C.A. 1975. The Native Orchids of the United States and Canada. New York Botanical Garden, Bronx, New York, USA.
Williams, S.A. 1994. Observations on reproduction in Triphora trianthophora. Rhodora 96:30-43.
Black Carpenter Ants
This series was taken on the joint outing of the WGNSS Entomology and Nature Photography Groups at Council Bluff Lake. Here we have eastern black carpenter ants (Camponotus pennsylvanicus) feeding on a freshly dead ring-necked snake (Diadophis punctatus).
The Bee Wolves
I was thrilled when I took my camera inside from shooting in my wildflower garden on a past summer day and identified this hymenopteran as a Bee Wolf. Philanthus gibbosus (Family Crabonidae) is what I am calling this one. Bee Wolves get their name from doing what you expect, feeding primarily on bees. These solitary wasps will load their brood chambers with pretty much any bee or wasp smaller than themselves that they can catch as a provision for a single egg they deposit prior to sealing the chamber shut. Some taxa have specific bees they prefer to catch and this can aid in identification. This poor thing was quite beaten up as you can see in the photograph below. Missing a few legs, it probably escaped a bird or larger insect, and was not happy to have me and my camera in its face. In the photo above I captured it doing a rapid vibration of its wings, something I read that these guys are known for doing as a communication. I can’t imagine what she may have been trying to tell me…
I believe the insect below to also be a species of Bee Wolf, but have not yet been able to put a name with this one. I photographed this one having a drink in a wet area of Shaw Nature Reserve early one morning.
-OZB
A Thousand Acres of Silphiums 