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INSECT PLANT INTERACTIONS OF TWO INVASIVE EUCALYPTUS
GALL INDUCERS, Leptocybe invasa FISHER & LASALLE AND
Ophelimus maskelli (ASHMEAD) (HYMENOPTERA: EULOPHIDAE), AND
MANAGEMENT POSSIBILITIES
MENDEL, Z. 1 ; PROTASOV, A. 1 ; SAPHIR, N. 2 ; BRAND, D. 2 , ASSAEL, F. 1 ;
BLUMBERG, D. 1 ; LA SALLE, J. 3
1 Department of Entomology, ARO, The Volcani Center, Bet Dagan, 50250, Israel
2 Forest Department, Land Development Authorities, JNF, Eshtha’ol 99775, Israel
3 Australian National Insect Collection, Entomology, Canberra, Australia
Since 2000 two species of gall wasps, Leptocybe invasa Fisher & LaSalle and
Ophelimus maskelli (Ashmead) are spreading throughout the Mediterranean basin
and Africa. Their massive presence and severe damage that they inflict on
eucalyptus stands drew the attention to the potentiality for great economic losses,
and for the adverse ecological impact to local eucalyptus forests. Both wasp
species induce galls on the leaf blade, with L. invasa also attacking the petiole and
the twig. Both species display bivoltinouos development with a long overwintering
period. Among the 80 Eucalyptus spp. that we tested, only those belonging to the
sections Exsertaria, Latoangulata, Maidenaria and Bisectae (subgen.
Symphyomyrtus) were found suitable hosts. These wasps injure the backbone
Eucalyptus species in the region: E. camaldulensis Dehnh., E. globulus Labill. and
E. grandis Hill ex Maiden. In Israel, the major impact of L. invasa is the degeneration
and growth setback of 1-4 yr old trees, caused by numerous galls on the petioles. O.
maskelii causes severe damage also to adult trees; in this case the outcome of the
heavy galling is a premature shedding of the leaves soon after the wasps’
emergence. Recent reports suggest that O. maskelli may cause health problems to
people (i.e., allergic reactions) standing near heavily infested trees during the mass
adult emergence. Systemic insecticides may effectively prevent the galling in
nursery stock and during the first growing season after planting. Both invading
wasps are free from their principal natural enemies occurring in Australia, but the
galls have been found inhabited by a non-describe Megastigmus spp.,
(Hymenoptera: Torymidae). The search for natural enemies of the wasps in
Australia is underway since October 2003. So far, three species of parasitic wasps
of O. maskelli were discovered in Australia, which are currently being reared in a
quarantine facility in Israel: Stethynium near flavinotae (Mymaridae),
Neochrysocharis sp. and a Tetrastichinae sp. (Eulophidae).
Key words: Eucalyptus, gall wasps, invasive species, management, parasitic wasps
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