Scientific name - Common names - Taxonomic position - Diagnosis - Images - Distribution - Hosts / Biology - References

Scientific name

Leptocybe invasa Fisher & La Salle

Common names

Eucalyptus gall wasp, Blue gum gall wasp

Taxonomic position

Hymenoptera: Chalcidoidea: Eulophidae: Tetrastichinae

Diagnosis

Adult: Female: Body dark brown with metallic greenish / bluish tinge. Wings hyaline or lightly and uniformly infuscate. Antennal formula 11433 (annelli four-segmented). Mesoscutum without a median line. Scutellum with prominent submedian carinae. Dorsellum prominent, as long as propodeum. Fore wing with two setae on submarginal vein; postmarginal vein very short, only about a quarter as long as stigmal vein. Mendel et al. (2004) have provided a detailed taxonomic description with illustrations.

Male: Similar to female in general appearance and coloration; antennal formula 11343 with scape having a narrow and elongate sensory organ on lateral margin, annelli three-segmented, funicle four-segmented with long latero-terminal bristles and less stout than in female, club three-segmented; abdomen somewhat tubular. Doganlar (2005) described the males as follows: head and mesosoma brown with distinct blue to green metallic shine, metasoma brown with a slightly metallic tinge, legs pale yellow, except mid and hind coxae which have metallic shine, and antennae yellow. Males are fewer and not commonly observed as the wasp is mainly thelytokous.  

    

 Female antenna

    Male antenna (arrow mark indicates scape with sensilla)

    Fore wing venation, female

    Fore wing venation, male

Larvae form galls on the leaves and tender shoots of Eucalptus spp.

Images

       

Larva inside gall

       

Pupa inside gall

       

Freshly emerged adult female

                

            

Adult female - dorsal view

        Adult female, dorsal view

Male of L. invasa, dorsal view    Male, dorsal view    Adult male, dorsal view

Adult male in lateral view    Adult male, lateral view

Distribution

Middle East, the Mediterranean, Europe, Africa (Mendel et al., 2004); L. invasa is thought to originate from Australia, but its situation in this country is unknown. Presently recorded from Algeria, France (including Corsica), Israel, Italy, Jordan, Morocco, Portugal, Spain, Turkey, Algeria, Jordan, Kenya, Morocco, Syria, Tanzania, Uganda, Iran, Israel, Thailand, Turkey, Vietnam, and India (known so far from Andhra Pradesh; Delhi; Karnataka; Kerala; Gujarat; Uttar Pradesh; Tamil Nadu).

Hosts / Biology / Symptoms of damage

Leptocybe invasa attacks many species of Eucalyptus including Eucalyptus botryoides, E. bridgesiana, E. camaldulensis, E. globulus, E. gunii, E. grandis, E. saligna, E. maidenii, E. robusta, E. tereticornis, E. viminalis, etc. The wasp causes typical bump-shaped galls on the leaf midribs, petioles, and stems of new growth of Eucalyptus spp., particularly in young plantations and nurseries. Heavy galling prevents further development of the infested growth. Mendel et al. (2004) described in detail the stages of gall formation and the biology of the wasp.  

The wasp reproduces by thelytoky (predominantly producing females). Eggs are inserted in the epidermis of the upper side of newly developed leaves on both sides of the midrib, petiole and parenchyma tissue of twigs, always in a lined group. The section of the leaf midrib carrying the eggs turn from green to pink 1-2 weeks after oviposition. The galls are spherical and glossy green initially and later turn from green to light or dark red depending on whether the galls are on leaves or the stem. The emergence holes are light brown on the leaves and reddish brown on the stem (Mendel et al., 2004). 

        Galls on seedlings    

    Eucalyptus leaf with oviposition injury        

       

         

Galls on midribs of leaves   

       

Adult emergence holes on galls

Two parasitoids of Australian origin, Quadrastichus mendeli Kim & La Salle and Selitrichodes kryceri Kim & La Salle (Hymenoptera: Eulophidae: Tetrastichinae) have been introduced against this pest from Israel and are in quarantine at present at the Project Directorate of Biological Control, Bangalore.

References