Gambrus tricolor (Gravenhorst, 1829)

Verheyde, Fons, Hoekstra, Paul, Libert, Pierre-Nicolas, Meijer, Hilco, Ketelaere, Augustijn De, Vandaudenard, Thibaud, Belgers, Dick & Brosens, Edwin, 1880, Two hundred and five ichneumonid wasps reported for the first time in Belgium and the Netherlands (Hymenoptera: Ichneumonidae), Belgian Journal of Entomology 122, pp. 1-142 : 57-58

Gambrus tricolor (Gravenhorst, 1829)

As mentioned above, Gambrus spp. superficially resemble species from the genus Agrothereutes . In contrast to these species however, Gambrus spp. have their mesoscutum matt, and the lower margin of the clypeus has a tooth or distinct angulation medially (SCHWARZ [2013], draft key). Ecology wise, species are often found in wetlands or riparian vegetation (for example reedbeds).

G. tricolor can be easily distinguished within the genus. It is the only species with a white scutellum and it has no orange coloration on the mesosoma. It is a known parasitoid wasp of the uncommon cephid wasp Phylloecus linearis (Schrank, 1781) (Symphyta: Cephidae ), which uses Agrimonia spp. as host plant ( SCHWARZ & SHAW, 1998; VERHEYDE & MEERT, 2020).

First report for the Netherlands; unconfirmed in Belgium.

MATERIAL EXAMINED:

THE NETHERLANDS: • 1 ♀; Drachten-Azeven (FR); 53°06’49”N 6°09’04”E; 13/ix/2020; H. Meijer leg.; coll. HM; field observation; H. Meijer det.