Classical biological control of two Eucalyptus gall wasps; main outcome and conclusions

Abstract The gall wasps Leptocybe invasa and Ophelimus maskelli (Hymenoptera Eulophidae) have become established in the Mediterranean Basin during the last 15 years. In contrast to the rarity of both gallers in Australia, they built up high, dense populations in their new areas. We examine and discuss the biological control project of both gallers in Israel and Portugal. Three species of parasitoids of O. maskelli – Closterocerus chamaeleon (Eulophidae), Stethynium ophelimi and Stethynium breviovipositor (Mymaridae) – were released in 2005, and four species of parasitoids of L. invasa – Megastigmus zvimendeli , M. lawsoni (Torymidae), Selitrichodes kryceri and Quadrastichus mendeli (Eulophidae) – were released in 2007. The level of galling was monitored. The findings revealed steep declines of both O. maskelli and L. invasa populations. Of the three species of parasitoids released against O. maskelli in Israel, only C. chamaeleon and S. ophelimi were recovered from galling material, of which the former species contributed much of the total parasitism. All four species of parasitoids released against L. invasa in Israel were recovered subsequently. Quadrastichus mendeli occurred most frequently among the parasitoids of L. invasa. The mean overall ratio among the occurrences of the four parasitoids, as observed in 2013, was 15:10:3:1 for Q. mendeli : M. zvimendeli S. kryceri : M. lawsoni , respectively. It seems that these species – two in the case of O. maskelli and four in the case of L. invasa , which were originally introduced into Israel now contribute to effective control throughout most of the Mediterranean.