Leptocybe invasa and Ophelimus maskelli, two gall wasps introduced in Tunisia
Two insects (Hymenoptera; Eulophidae) were detected in Tunisia on the foliage of E. camaldulensis trees: Leptocybe invasa recorded in 2004 and Ophelimus maskelli recorded in 2006. These wasps are both gall inducers and cause damages mainly to eucalyptus seedlings in nurseries and young plantations.
The main objective of this factsheet is to help technicians and forsters to recognize, in the field, insect gall wasps of Eucalyptus species.
Leptocybe invasa, the Australian gall wasp, is present in the Mediterranean area, the Middle East, and Africa. It was detected in Italy in 2000, in Portugal and Spain in 2003, two years later in Turkey and Iran. In 2005, it was detected in the South of France and in 2006 In Algeria. the female (Fig. 1), is of 1.1-1.4 mm in length. It induces galls on petioles, leaf midribs and young branches of several Eucalyptus species such as E. camaldulensis, E. tereticornis, E. rudis, E. grandis, E. globulus and E. viminalis (Fig. 2). Larval developmental proceed into the gall of a mean length of 2.1 mm (fig. 3). Mendel et al. indicated that under laboratory conditions, this wasp lasts 132.6 days from oviposition to adult emergence and may produce two or three generations annually. Intense infestations can lead to deformations of the leaves and young stems and the reduction of tree growth.
Ophelimus maskelli (Fig. 3) was reported from many Mediterranean areas and was first identified, in Italy and Northeast Spain, as O. eucalypti. In 2003, this pest was reported in the Middle East and Spain. In 2005, it was reported from the South of France and in 2006, in Portugal and Turkey. This eulophid induces galls on the limb of leaves of several Eucalyptus species such as E. camaldulensis, E. tereticornis, E. rudis, E. grandis, E. cinerea, E. robusta, E. botyoides, E. viminalis, and E. saligna (Fig. 4). Female, of 0.83 to 1.07 mm in length lays about 100 eggs with a preference next to petiole, but in heavily attack all the leaf surface is covered with galls with a density reaching 36 galls/cm2
These gall wasps develop several generation per year, technicians and forester must survey eucalyptus species in the field and in the nurseries over all the year
In order to succeed in future reforestation programs with Eucalyptus species, it is essential to choose the best acclimated species but also those that are more resistant to the attack of these two gall wasps.