Behaviors of Hedychrum gerstäckeri female

[Christine Devillers]

Hello,
In June I saw 3 females of Hedychrum gerstäckeri entering in several nests of Cerceris rybyensis. When they came out of the nest, they sometimes scraped the edges of the nest with their legs for 1 to 2 minutes (pictures 2 – 5), making the earth fall into the nest as if they wanted to partially fill it before the Cerceris came back.
Sometimes they stayed immobile close to the nest (at about 4 cm). If another female of Hedychrum gerstäckeri approached the nest entrance, the one waiting nearby runned towards her (while opening and closing a few times her wings) and made her go away before she went down into the nest. Then she went back to her original position at a distance of 4 cm from the nest.
I’ve also seen a female Cerceris rybyensis returning to her nest with an Halictidae and when she has seen the female of Hedychrum immobile near her nest, she rushed towards her and hit her. The Hedychrum moved away for a short distance but when the Cerceris had entered the nest she came back at the same place.
Have you ever heard of those behaviours ?
Thanks
Christine

[Euchroeus]

Hi Christine,

thanks for your observations.

Yes, I already observed this behaviour.
Perhaps, the female who filled the nest with some sand and defended the nest against other kleptoparasites just laid her egg.
Attacks of Cerceris are known in literature and there are some interesting publications on the behaviour of Hedychrum published in the last years. The most famous is:
Strohm, E., Kroiss, J., Herzner, G. et al. A cuckoo in wolves' clothing? Chemical mimicry in a specialized cuckoo wasp of the European beewolf (Hymenoptera, Chrysididae and Crabronidae). Front Zool 5, 2 (2008). https://doi.org/10.1186/1742-9994-5-2
have a look also at this one:
Strohm E, Laurien-Kehnen C, Bordon S: Escape from parasitism: Spatial and temporal strategies of a sphecid wasp against a specialised cuckoo wasp. Oecologia Berlin. 2001, 129 (1): 50-57. 10.1007/s004420100702.

[Christine Devillers]

Hi Paolo,
Thanks for those informations.
I’ve seen that you have just published a new book « Die Goldwespen Mitteleuropas » with Heinz Wiesbauer and Herbert Zettel. I just ordered it and I am looking forward to read it.

[Euchroeus]

Thanks Christine,

let me know your opinion!

Ciao
Paolo

[Christine Devillers]

Hi Paolo,

Congratulation. Great work, very interesting and a lot of very nice illustrations. I am very happy to have bought it.

Christine