A Mite-y Beetle Observation in Austria - Observation of the Week, 7/13/21

Our Observation of the Day is this mite-covered Burying Beetle, seen in Austria by @karimstrohriegl!

Currently a student working on his Bachelor’s Degree in Biology at the University of Graz, Karim Strohriegl had the opportunity to visit Austria’s Thayatal National Park last month, on a trip organized by Österreichische Entomologische Gesellschaft (ÖEG), an entomological organization. “The goal,” he says, “was to collect and/or identify as many species as possible and provide a species list to the national park.”

A Lepidoptera expert installed a light trap and I was taking shots of all kinds of different insects. When photographing a burying beetle of the genus Nicrophorus I was surprised to see that it was full of Gamasina [mites]. I had never seen an insect with that many mites on it and was amazed learning that they had a phoretic relationship.

Yup, while it looks as though that beetle is being devoured by the mites, it actually flies around with some (although usually not that many!) on its body, hence Karim’s use of the term “phoretic”. Members of the genus Nicrophorus are commonly known as “burying beetles” in English and they do specialize in decomposing dead animals. Using their mandibles and secretions from their mouth and anus, they’ll chew up and preserve the carcass, which they feed to their larvae. 

However, other carrion eaters like flies often reach the carcass and lay eggs on it before the beetle gets there. That sets up a competition between fly maggots and beetle larvae, which is where the phoretic mites (who are using the beetle as transportation to the carcass) come in. Entomologist Joe Ballenger writes:

The beetles can take care of some of [the maggots], but not all of them. This is where those mites come in. Those mites are specialists on fly eggs, and hungrily devour the eggs and young larvae. This keeps the flies from stealing the food that the beetles need to rear their larvae.

This relationship has another aspect, though. The mites can’t feed on anything bigger than they are, so they need the beetles to raise the mite larvae. The mite larvae feed off the same secretions the mother beetles use to feed their babies.

Beetles, mites, and flies are, of course, awesome, but the study of bees is what Karim (above) is focused on. He’s working on a bee project run by Naturschutzbund Steiermark and says “My main goal is to learn everything about wild bees and to be able to ID as many different species as possible.” He’s started to compile photo resources for bee identification on his website and hopes it will have many more species by the end of the summer.  

Learning to identify bees is also one of the reasons he uses iNaturalist, in addition to getting ID help and having a public database for his observations. 

At least half of my knowledge identifying bees I got through iNaturalist and the interactions with other users like @johnascher or @robertzimmermann. I also would like to thank my University Professor Gernot Kunz (@gernotkunz), who I think is the biggest fan of iNaturalist and who brings hundreds of students every year to the platform. His photographs inspired me to get into macro photography and through that I am paying so much more attention to my surroundings. Now I can photograph the smallest of the small and it’s amazing to see how beautiful these little creatures are.

(Some quotes have been lightly edited for clarity and flow.)

- There are some pretty good (albeit gruesome) videos online showing Nicrophorus beetles doing their thing. Here’s one from National Geographic, another from the Smithsonian, and this awesome narration-free video with great larvae-feeding and metamorphosis footage.

- Hopefully this inspires you to set up some lights and participate in the worldwide National Moth Week starting July 17th! More information here.

- Another phamously phoretic (sorry, I couldn’t resist) arachnid is the pseudoscorpion, and @abhiapc’s photos of some was a recent Observation of the Week!

Posted on July 13, 2021 11:03 PM by tiwane