A Unique Look at a Unique Wasp Cocoon - Observation of the Week, 10/19/20

Our Observation of the Week is this Praon wasp pupa (and its aphid host), seen in the United Kingdom by @lee_i1978!

“Though it would be great to be able to regale you with a story of trekking for miles into the wilds,” says Lee Ismail, a Curator of Natural Sciences at Brighton Museums in the United Kingdom, “the story behind the observation is fairly mundane and is possibly the most comfortable nature observation possible!” While at home, Lee walked past his window and noticed the strange structure and organism you see above. 

Initially thinking it was the underside of a tiny snail, I noticed wings as I passed, causing me to pause and take a closer look. That's when I noticed that it was an aphid of some sort, but was stuck to the window with a suction cup shaped structure, tied down with fine silk strands.

He originally posted it to iNat with an ID of Animalia, but after doing a quick search on “Aphid with suction cup structure”, he saw it was the pupa of the wasp genus Praon, a member of the Subfamily Aphidiinae, which all parasitize aphids. A few other iNat users agreed, and @haukekoch provided a link to this paper describing a species in the genus, Praon volucre, which is fascinating. 

According to author Bryan P. Beirne, female wasps oviposit on aphids or on anything that resembles an aphid. The larva eats its host from the inside, and by its fourth instar usually kills its host,

and as a result of its consuming the decaying parts of the Aphis the alimentary tract of the larva, which in previous instars is greenish or greyish, becomes dark brown in this and the following instars and so the larva becomes visible through the integument of the Aphis.

When it reaches its fifth instar, the larva cuts open a hole in the aphid body and spins its suction cup-like cocoon, where it pupates. This is usually attached to a leaf, but in the case of Lee’s observation, it attached itself to his window, giving us a glimpse into its underside! As Lee says, “[this find] does neatly demonstrate that there is fascinating nature all around us though (we're always trying to convince visitors of this at the museum!)”

One of only two people specifically based in caring for the natural history collections at the Royal Pavilion and Museums Trust, Brighton, Lee (below) says 

we don't have much time to carry out our own research, and our input into research is in assisting those who use our collections for their research. Most recently this has included DNA sampling for king cheetahs, determining population genetics for Peregrine Falcon populations in Southern England and identifying new species of lepidoptera from British Guiana.

He’s also been working on his nature photography skills, particularly macro photography of late, both to illustrate work-related blog posts and, since being furloughed, “I have continued to photograph nature for the pure pleasure of enjoying the natural world!”

Since starting on iNat in this year’s City Nature Challenge, Lee, who grew up in Southern England, Malaysia and Oman, tells me

Though I'd used similar sites in the past, I found iNaturalist to be really user friendly, and so I continued to post observations after the CNC2020 had finished. Initially I started recording observations I'd made on visits around the world as well as at home in the UK. Since then I've recorded regular observations I've made both at home and on walks around Southern England during travel restrictions and furlough. 

iNaturalist hasn't changed how I see the natural world, but it has changed how I interact with it. I'd always noted where I'd observed interesting nature but hadn't recorded those observations anywhere accessible to the wider community…

Whilst I have no idea what the data may eventually be used for, it is gratifying to see observations made on vacation being added to projects such as Kea Monitoring (https://www.inaturalist.org/observations/44099262) or US Federally and Endangered Species (https://www.inaturalist.org/observations/44102776) projects. The site is also great at seeing just how many different species I've seen over the years.

Here’s a wasp ovipositing on an aphid, although I personally can’t confirm whether it’s an adult Praon or not. Pretty cool, though!

Posted on October 19, 2020 09:37 PM by tiwane