Giant pine scale (GPS), Marchalina hellenica is an exotic sap sucking scale insect that was detected feeding on the novel host Pinus radiata in Adelaide and Melbourne in late-2014. This scale insect is native to the eastern Mediterranean region (mainland Greece and Turkey) where it is considered an economically important insect in the apiculture industry. GPS is a concern in Australia because high population densities can lead to a decline in tree health and reduction in insect biodiversity. Importantly, GPS is a threat to Australia’s $1.16 billion soft wood industry as it attacks the dominant commercially grown species P. radiata. There are currently no effective control options. Complete destruction of infested tress is currently being used to prevent the spread of GPS from urban and peri-urban areas to commercial pine plantations.

A feasibility study carried out by Agriculture Victoria identified Neoleucopis kartliana (Diptera: Chamaemyiidae) as the most promising biological control agent of GPS. Recent studies in Greece involving field surveys and molecular analyses have revealed that N. kartliana sensu lato is a species complex comprising three species: N. kartliana sensu stricto, N. sp. nov. A. and N. sp. nov. B., of which only N. kartliana sensu stricto has been described. It is likely that all of these three species play a role in suppressing GPS populations in Greece and therefore have high potential for use as biological control agents for GPS.

This research aimed to assess risks associated with the introduction of potential biological control agents of GPS and determine the agents’ suitability for long-term, sustainable management of GPS in Australia. Preliminary laboratory and field results from Greece indicate N. sp. nov. B to be highly prey specific. If approved for release, N. sp. nov. B, will complement other management practices to suppress GPS populations, reduce the impact of GPS on susceptible trees, and slow the spread of GPS into commercial softwood plantations.