Interactions between hymenopteran species associated with gall-forming wasps: theLeptocybe invasacommunity as a case study

Leptocybe invasais native to Australia and induces galls on various species ofEucalyptus. Two genetically distinct lineages of this wasp have been detected outside its native range, namely,LeptocybeLineage A andLeptocybeLineage B. The parasitoidSelitrichodes neseriwas released in South Africa as a biological control agent againstL. invasa. Another parasitoid ofL. invasa,Quadrastichus mendeli, as well asMegastigmus zebrinus(parasitoid) andMegastigmus pretorianensis(role unknown), have also been recorded emerging fromL. invasagalls. The objective of this study was to investigate the interactions between the different hymenopterans associated withL. invasagalls in South Africa. L. invasagalls were dissected and species-specific primers and restriction enzymes were used to identify the larvae where interactions were noted. S. neseri,Q. mendeliandM. zebrinuswere confirmed to parasitizeLeptocybeLineage A, andS. neseriwas confirmed to parasitizeLeptocybeLineage B. Furthermore, there were direct interactions between these parasitoids, where parasitoids were found parasitising each other. The gall forming experiment confirmed thatM. pretorianensisis not a gall former, but other potential roles remain uncertain.