Figure 1: Thaumastocoris peregrinus adult

Originally misidentified as Thaumastocoris australicus, Thaumastocoris peregrinus was first discovered in South Africa in 2003 and Argentina in 2005. The initial misidentification of Thaumastocoris peregrinus highlights the difficulty in morphologically differentiating between these two species. The misidentification of species has implications for species specific control strategies, collection of potential biological control agents in addition to understanding the spread of a species. A solution to overcome this problem is through the use of mitochondrial DNA (mtDNA) bar-coding for species identification. DNA bar-coding uses a region of the mtDNA cytochrome c oxidase subunit I (CO I) gene to identify species based on sequence variation from an identified species. mtDNA sequencing of the CO I gene results in significant sequence variation among different species in comparison to little sequence variation occurring within individuals of the same species.

In this study we used DNA bar-coding sequences from native populations of T. peregrinus from three regions in Australia (Sydney, Brisbane and Perth) and compared these to those of specimens from both South African and South American Eucalyptus plantations.Analysis of the bar-coding sequences of native Australian populations revealed three distinct species based on the level of mtDNA sequence divergence (Figure 2). One species occurs exclusively in the Perth region of Western Australia, the second species occurs within the Sydney region and third species identified as Thaumastocoris peregrinus occurs in Brisbane, Sydney Australia in addition to the non native regions of Argentina, Brazil, South Africa and Uruguay.

Bar-coding was also used to assist in determining the potential source and pattern of invasion of T. peregrinus in South Africa and South America. Three T. peregrinus haplotypes, dominant in Sydney, were also found among the populations in South Africa and South America, indicating that most likely a small number of individuals were introduced into these areas. The presence of three distinct haplotypes, two in South Africa and one in South America indicates that T. peregrinus has not moved between these continents, but they almost certainly represent separate introductions from Australia. This study has shown that Sydney populations of T. peregrinus that regularly reach outbreak levels in recent years might thus have served as the source populations of these three distinct introductions of T. peregrinus into other regions of the Southern Hemisphere.

REFERENCE

Nadel R.L., Slippers B., Scholes M.C., Lawson S.A., Noack A.E., Wilcken C.F., Bouvet J.P. and Wingfield M.J. (2010)  DNA bar-coding reveals source and patterns of Thaumastocoris peregrinus invasions in South Africa and South America. Biological Invasions: Volume 12, Issue 5 , Page 1067 - 1077

The original publication is available at www.springerlink.com