Pest Alerts - A Eucalyptus Pest, Leptocybe Invasa

Pest Alert

A Eucalyptus Pest, Leptocybe invasa Fisher and LaSalle (Hymenoptera: Eulophidae), Genus and Species New to Florida and North America

Jim Wiley, Biological Scientist I, Florida Department of Agriculture and Consumer Services, Division of Plant Industry

Paul Skelley, Paul.Skelley@FreshFromFlorida.com, Taxonomic Entomologist, Florida Department of Agriculture and Consumer Services, Division of Plant Industry

INTRODUCTION: Galls were found on the stems and leaves of a Eucalyptus tree in Lauderhill (Broward County, E2008-4347-1; William A. Thiel, USDA, 2 July 2008). It was suspected that the galls were caused by the blue gum chalcid, Leptocybe invasa Fisher & LaSalle (Hymenoptera: Eulophidae). Specimens were reared and submitted to Dr. Michael Gates (Systematic Entomology Laboratory, USDA-ARS, Washington DC) for confirmation of identification.

This gall-forming wasp was described from Australia in 2004 (Fisher and LaSalle 2004). Within the past decade, it has become established in the Mediterranean Basin, Sub Saharan and South Africa, India, Southeast Asia and Brazil (Anonymous 2007; Kumar et al. 2007; Mendel et al. 2007; Kim et al. 2008).

DESCRIPTION: The female adult wasp is 1.1-1.4 mm long (Fig. 1). The body is brownish in color with a blue to green metallic sheen. Fore coxae are yellow, mid and hind coxae brown. The scape of the antennae is yellow, with the rest of the segments brown. Males are unknown.

The blue gum chalcid produces galls in the form of distinct swellings on the petioles, leaf midribs and stems on new foliage of both young and mature trees (Fig. 2). Galling causes the leaves to curl and may stunt the growth and weaken the trees; thus, L. invasa can cause substantial damage or death to young trees. The impact on adult trees is not known.

HOSTS: Mendel et al. (2004) tested 36 species of Eucalyptus and found ten to be suitable hosts: Eucalyptus camaldulensis, E. tereticornis, E. botryoides, E. grandis, E. robusta, E. saligna, E. bridgesiana, E. globulus, E. gunii and E. viminalis. In Florida, L. invasa damage has been confirmed on E. camaldulensis, E. grandis, E. propinqua, E. rudis and E. dunnii.

BIOLOGY AND ECONOMIC IMPACT: The female wasps insert their eggs into the upper side of the leaves and stems. As the larvae develop, galls begin to form and the green color of the leaves containing the galls turns glossy pink. The glossiness then declines and the galls turn from pink to red. Upon emergence of the adult wasps, the galls on the leaves turn light brown and the galls on the stems turn reddish brown.

Galls caused by this wasp can result in substantial injury to young trees and can seriously weaken or kill the tree. All new growth is susceptible to damage when large concentrations of these wasps are present. As Eucalyptus is used as both an ornamental and commercial tree in Florida, L. invasa has the potential of becoming a problematic pest.

Two parasitoids are known for this wasp: Quadrastichus mendeli Kim & LaSalle and Selitrichodes kryceri Kim & LaSalle (Hymenoptera: Eulophidae: Tetrastichinae), which may offer a potential for biological control (Kim et al. 2008).

FLORIDA DISTRIBUTION: Leptocybe invasa is presently known from Broward County (2008), Palm Beach County (2009), Glades County (2009), Hendry County (2009), Lee County (2009) and Dade County (2009).

Adult female wasp of Leptocybe invasa.

Fig 1. Adult female wasp of Leptocybe invasa.
Photography credit: P. Skelley, FDACS/DPI

Galls of Leptocybe invasa on Eucalyptus from Florida

Fig 2. Galls of Leptocybe invasa on Eucalyptus from Florida
Photography credit: P. Skelley, FDACS/DPI

SELECTED REFERENCES:

  • Anonymous. 2007. Blue gum chalcid. FABI Pest Alert. 
  • Fisher, N., and J. LaSalle. 2004. In: Mendel et al. 2004.
     The taxonomy and natural history of Leptocybe invasa (Hymenoptera: Eulophidae) gen. & sp. nov., an invasive gall inducer on Eucalyptus. Australian Journal of Entomology 43: 101-113.
  • Kim, I.-K., Z. Mendel, A. Protasov, and J. LaSalle. 2008. Taxonomy, biology, and efficacy of two Australian parasitoids of the eucalyptus gall wasp, Leptocybe invasa Fisher & LaSalle (Hymenoptera: Eulophidae: Tetrastichinae). Zootaxa 1910: 1-20.
  • Kumar, S. S., S. K. Kant, and T. Emmanuel. 2007. Emergence of gall inducing insect Leptocybe invasa (Hymenoptera: Eulophidae) in Eucalyptus plantations in Gujarat, India. Indian Forester 133(11): 1566-1568.
  • Singh, K. 1931. A contribution towards our knowledge of the Aleyrodidae (Whiteflies) of India. Memoirs of the Department of Agriculture in India. 12: 1-98.
  • Mendel, Z., A. Protasov, N. Fisher, and J. La Salle. 2004. The taxonomy and natural history of Leptocybe invasa (Hymenoptera: Eulophidae) gen. & sp. nov., an invasive gall inducer on Eucalyptus. Australian Journal of Entomology 43: 101–113.

Page created 01-December-2008 [updated 16-March-2010]