Hedychrum virens and Cerceris tuberculata

Notes on the biology of Hedychrum virens and Cerceris tuberculata

Text and photos by Paolo Rosa.

In the summer 2006 I was in Ukraine to meet my colleague Alina Drozdovskaya of Kyiv Taras Shevchenko National University, and to conduct some hymenopterological researches.

In the month of July we were in Crimea, in and around the famous wildlife park of Karadagh on the Black Sea coast. During an excursion we had the opportunity to meet a colony of Cerceris tuberculata de Villers, 1789, nesting in the ground behind some bushes. With great surprise we observed some Hedychrum virens Dahlbom, 1845 moving on the soil. We have spent few days to observe the behavior of Hedychrum and their hosts, taking some pictures of the predation and parasitism of Cerceris against Curculionidae beetles and of the activity of Chrysidids.

click images to enlarge:

Cerceris specimens were seeking for their victims on the ground, Larinus onopordi (F., 1787) curculionids. Once found, the Cerceris was taking the beetle with the large jaws and was injecting the paralyzing poison in its body. Then the prey was dragged on the ground, sometimes with low level flights, up to the nest, where the beetle was introduced with a big effort. In the meantime, Hedychrum virens, the largest European elampine chrysidid, had visited all the nests meticolously, although we didn’t see a single case of ovideposition.

In truth there’s no doubt about the parasitism of that chrysidid because in several days of field observations we have never noticed any other chrysidids in the colony’s site. Moreover, the size of the host and of its prey leave no doubts. Only one more parasite was common at the site, a velvet ant presumably belonging to the genus Smicromyrme.

Camera: Nikon Coolpix 5000, automatic esposure.

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