On the biological cycle of the gall wasp Plagiotrochus suberi Weld 1926 (Hymenoptera: Cynipoidea: Cynipidae) in the circum-Mediterranean region

J. PUJADE-VILLAR; GARBIN, L.; JORDI PARETAS MARTÍNEZ; NORMA B. DIAZ

CONTRIBUTIONS TO ZOOLOGY - (Print)

Naturalis, ISSN 0067-8546

Lugar: Leiden , Holanda; Año: 2008 vol. 77 p. 249 - 249

0067-8546

Oak gall wasps (Cynipidae: Cynipini: Plagiotrochus)that induce galls on Quercus reproduce by alternatesexual and parthenogenetic generations (Pujade-Villaret al., 2001). However, a few species are obligatoryparthenogenetic (Abe, 1998) or show the facultativealternation of generations (Folliot, 1964).Plagiotrochus suberi Weld 1926 is an asexual gallwasp from North America that is found on the biennialbranches of cork oaks. The species originates from thecircum-Mediterranean region and was introduced tothe American continent centuries ago, together with itshost, Quercus suber L. The general biology of P. suberiwas described by Bailey and Stange (1966) and Díaz(1973) for California and Argentina, respectively.Zuparko (1996) demonstrated experimentally that P.suberi reproduces parthenogenetically in North-America.It was mentioned for the fi rst time in Europe byBailey and Stange (1966) from material collected bythe Swiss entomologist Charles Ferrière in Lugano(Switzerland). Plagiotrochus amenti Kieffer 1901 is asexual gall wasp from Europe described from a catkingall on a cork oak in Portugal (see the redescription ofthe sexual adults and the galls by Tavares, 1902). Theavailable data indicate that P. suberi and P. amenti aremorphologically very similar.We performed studies in which we experimentallyterminated the biological cycle of P. suberi, startingfrom the asexual form in the circum-Mediterraneanpopulations. These experiments revealed an alternatinglife cycle of P. suberi in the original area of distributionand in front of the parthenogenetic in the Americanpopulations. Although the experimental data andthe implications of this reproductive duality are notpresented here, our data confi rm that P. amenti and P.suberi are the sexual and asexual form, respectively, ofthe same species. We conclude that Plagiotrochusamenti Kieffer 1901 is the valid name of this speciesaccording to the nomenclatorial priority rule and thatP. suberi Weld 1926 is a junior synonym.