In Malawi, a Wasp Nest is Raided by a Large Hive Beetle - Observation of the Week, 3/22/22

Our Observation of the Week is this Ropalidia distigma paper wasp nest being raided by a Large Hive Beetle (Oplostomus fuligineus). Seen by @lemoncul in Malawi.

After growing up in Luxembourg, Marc Henrion (@lemoncul) moved to London for university and postdoc training, then to New York for a postdoc position. While he always had an interested in nature, Marc tells me “it really took off when I moved to the US and discovered the national parks with their impressive wildlife and the realisation that I would need a much better camera.”

After moving to Malawi a few years later, he says

[I] was blown away by the birdlife, though I had to learn a lot. I work in international public health research, but luckily my office mate [@markusgmeiner] was active on iNaturalist and got me hooked into systematically logging my observations and helping with IDs. I am always interested in large mammals, but birds really are my passion. Reptiles, amphibians and insects are a bonus when out and about but not my main interest.

And we’re lucky Marc is interested in non-bird wildlife, otherwise we might not have gotten a look at the tableau you see above. It’s actually due to his forgetting his binoculars at home before heading out to Majete Wildlife Reserve in southern Malawi a few weeks ago. “So,” he says,

instead of looking for birds, leopards and wild dogs, I decided to have a more entomologically focused weekend as I could use my phone camera to record observations that way - a phone is not ideal for birdwatching... So in the evening I walked around the campsite with a flashlight and my phone. I then spotted the beetle stuck in a wasp nest on one of the shower blocks. I wondered what the beetle was doing there, and thought it had been the victim of the wasps. Only after posting it on iNaturalist and the beetle being ID'ed (by @opolasek and @beetledude) did I find out that the beetle was the parasite in this situation - really cool when you learn something new.

I reached out to Ozren (@opolasek) for more information about this interaction, and he told me

The observation by lemoncul shows a real problem for a wasp colony, a hive chafer. These coleopterans can raid wasp colonies and cause a substantial loss of larvae and destruction of the nest. However, in all observations on iNaturalist, the wasps do not mount a reaction or try to defend the brood. This is very interesting, but we are unaware why the wasps do not react. The chafer may use chemical signals to pacify the wasps, and one of the wasps in this photo seems to lick the chafer. 

Adults of this species (which also raid honey bee hives), eat, meet, and mate on nests, after which the female will lay her eggs in mammal dung. Larvae eat and pupate within the dung, emerging as adults on the prowl for hymenopteran nests.

The wasp species, Ropalidia distigma, is one of the most common in the area, says Ozren, and makes nests containing about 50 adults, often on trees or human structures. A citizen scientist with a “keen interest in the family Vespidae,” Ozren has been working with others on a revision of African Ropalidia. 

Notably, [Ropalidia distigma] will soon change the name, and it will become Ropalidia puncta, a taxonomic change that will resolve nearly 218 years of confusion of one type specimen described by Fabricius in 1804. This finding is a part of the large revision of this genus, where five colleagues helped produce a revision of African species. The study described 33 new African species and included 528 documented observations of these wasps collected on iNaturalist website. This study was recently accepted for publication by the journal Zootaxa.

Marc (above, second from right), tells me he uses iNaturalist for three main reasons:

1. Logging my observations - for my own records and for contributing to research.

2. Finding out what I've seen -- I learned a lot about species that I had no idea what they were when I recorded them and getting the online community to identify them.

3. A bit of friendly competition to see who is the top observer in Malawi (though @markusgmeiner will be difficult to overtake...) ;-)

(Photo by Oliver Pearse (@opearse), taken in Nsanje, Malawi. From left to right: Innocent Chapo, a local community leader; Alic, a forestry department ranger; Alex (@globalorthop); Innocent's son Hassan who was our guide; Marc (@lemoncul); and Markus (@markusgmeiner).)

- A paper based on GBIF data (which included iNaturalist observations) made a model to predict the spread of large hive beetles, and you can read it here! Also includes some pretty interesting information about their behavior and effect on honey bee hives.

- Ozren and some colleagues recently described a new speices of Ropalidia, and their investigation was spurred by this observation by @happyasacupcake. The paper will soon be published in Journal of Hymenoptera Research.

Posted on March 22, 2022 08:05 PM by tiwane