Here are a series of images I shot during the course of a summer day in Vancouver. All are hymenopterans, which, in addition to being tasty, are of course the best insects out there.
A nest I uncovered of Myrmica specioides, a recent introduction on the West Coast.
A big Megachilid.
Myrmica rubra against the sky (bribed with a bit of honey).
I have always wanted to get a shot of one of these chrysidid beauties. I believe it is Pseudomalus auratus.
A gorgeous Philanthus beewolf, showing just how much they really do love flowers.
A queen and workers of Myrmica rubra, the European Fire Ant.
Myrmica rubra tending aphids, a few of which appear to be mummies.
Ammophila wasps at sunset, shot with the 300 mm lens.
Yesterday was cold and wet at Iona Beach, where I set out for an insect photography walk. The conditions were a bit uncomfortable for me, but it was not raining so much that I could not use my camera. To make up for the wet misery, I found such a lot of cool things that it will take a series of blog posts to cover them all!
This subject came up as I was just leaving the beach, aiming to warm myself up in a hot shower when I glanced down and saw a little cluster of sleeping bees. Looking around on adjacent flowers, I found that there were 5 such clusters! This was too good to pass up, so I buckled down and started shooting despite the cold.
Here are a couple of the other clusters:
I am no expert on solitary bees, so I would love to know what these are. I initially thought they were Halictus, but I am beginning to wonder about that…Whatever they are, they are all males, as they have very hairy faces (most female solitary bees are all business in the front).
Update! These are apparently Colletes males. Thanks to John Ascher for the ID!
Having such still subjects allows some experimentation with lighting and background…
Here they are against the overcast sky. This was a single diffused flash to the upper left of the cluster and a white bounce card held immediately to the right.
Here I have the diffused light to the upper right, and the bounce card behind (with a flash pointed at it) to blow out the background. In hindsight, maybe I should carry two cards!
Here I am using a single diffused light to the upper left, a bounce card to the right, and the background lit with the second flash using the Monster Macro Rig.
Here the setup is similar to the above, except the background is mostly dark and the second light throws hard light to the right and rear.
Sleeping bees are awesome…Now I have yet another search image burned into my brain for when I go out in the mornings and evenings!
As I urge you always, go out and find some sleeping Hymenoptera! They are great subjects for photography!
I mentioned that I had a good photography day at Iona Beach…Here is a hint at what comes next:
Red-throated Caracaras are specialist predators of the brood of social paper wasps, as our previous research confirmed. The big question we wanted to answer was: how do they manage to attack and subdue the workers of these well-defended wasp nests? A previous study by Jean-Marc Thiollay suggested that Red-throated Caracaras may possess a chemical repellent that keeps the wasps from approaching and attacking them, but this hypothesis was never tested.
We sought to shed more light on this by sampling chemicals from the birds and by observing the predation behavior firsthand.
To do this, we set up a “feeding station” to record the caracaras attacking wasps. We lured the caracaras near to the video arena by playing recordings of their vocalizations from an amplifier near the site. The birds would come to investigate the source of the calls, and once they saw the wasp nests we had set out there, the caracaras went in for the kill, and we captured the behaviour on video.
This is the video arena we set up in the forest behind the camp. Maintaining the condition of the “waterproof” video cables and connectors was very difficult in the rainy season!
These are the five species of paper wasps we managed to get the caracaras to attack.
The caracaras did not seem to have significant problems with the smaller wasp species Polybia bistriata, Polybia scrobalis or Polybia affinis. None of these seemed to attack the caracaras at all. But check out the following video of an attack on a larger Polybia jurinei nest:
The caracaras knocked two of these nests to the ground, and later flew down to retrieve them. In another attack on a nest of Polybia jurinei, the caracaras repeatedly slammed into the nest, and eventually the wasps abandoned their defense. These situations where the wasps abandon their nest represent a behaviour known as absconding. The swarm-founding wasps, with sufficient nest disturbance, can fly off en masse to quickly found a new nest elsewhere. They lose that batch of brood, but save the workers from an ultimately futile defense of the nest.
My suspicion is that larger nests than these would put up much more of a fight. Unfortunately, we never got to record attacks on some of the truly huge nests that can occur in the tropics. We did record the aftermath of one such attack on Polybia dimidiata:
The video data do tell us that the type of chemical defense envisioned by Thiollay does not seem to be how the caracaras avoid wasp stings, but we did look for potential chemical repellents anyway.
Sampling from a caracara face using solvent-soaked cotton swabs. We also sampled the feathers and feet, using both methanol and hexane.
We anticipated that any potential chemical repellents would be detectable by the antennae of sympatric wasps, so we brought nests of Polybia bistriata back to the lab to test the caracara extract for compounds perceptible to wasps using coupled gas chromatography/electroantennography (GC/EAD)
As you can see from this example GC/EAD recording, Polybia bistriata antennae respond to several components of the caracara foot extract (the top trace shows the chemicals, the bottom shows the antenna’s response). Compound A is sulcatone, while the compounds labelled B are iridodial isomers, and compound C is a boring old fatty acid (which is found on most animals). Iridodial and sulcatone are repellent compounds, but best known from dolichoderine ants, such as Azteca.
We suspected that the caracaras may have picked up these compounds from Azteca ants. To follow up, we sampled Azteca chartifex near the field station at Saut Pararé and compared their pygidial gland secretions with the caracara foot extracts using GC/MS.
At the top is the GC/MS trace of the Azteca sample, at the bottom is the trace from the caracara feet. Notice the shared ketones and the iridodial isomers. We found these ant-type compounds only on the feet, suggesting that the caracaras are attacked by Azteca while perching.
And this is why we suspect caracaras come into contact with Azteca! Polybia rejecta nests in close association with Azteca, which protect the wasp nests from army ants. It could well be that the caracaras are attacked by Azteca while preying on these wasps. It is also possible that the caracaras are just incidentally attacked while perching on Azteca-infested trees. Photo provided by Pablo Servigne.
In summary, the caracaras do not have much difficulty with smaller species such as P. bistriata; just tearing into the nest is sufficient to cause these wasps to abscond. With larger species, the caracaras have to use more persuasive tactics, such as knocking the nest to the ground or striking it repeatedly. While it does not seem the caracaras have chemical repellents, the discovery of the ant-derived defensive chemicals highlights the surprisingly intricate connections between organisms in the rainforest.
